IDEC PHARMACEUTICALS CORP / DE, S-3, 1998-02-24

IDEC PHARMACEUTICALS CORP / DE
S-3, 1998-02-24
BIOLOGICAL PRODUCTS, (NO DIAGNOSTIC SUBSTANCES)

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<PAGE> 1

AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON FEBRUARY 24, 1998

REGISTRATION NO. 333-
================================================================================
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
------------------------

FORM S-3
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933
------------------------

IDEC PHARMACEUTICALS CORPORATION
(EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
------------------------

<TABLE>
<S> <C>
DELAWARE 33-0112644
(STATE OR OTHER JURISDICTION OF (I.R.S. EMPLOYER
INCORPORATION OR ORGANIZATION) IDENTIFICATION NUMBER)
</TABLE>

11011 TORREYANA ROAD
SAN DIEGO, CA 92121
(619) 550-8500
(ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER, INCLUDING AREA CODE, OF
REGISTRANT'S PRINCIPAL EXECUTIVE OFFICES)
------------------------

PHILLIP M. SCHNEIDER
CHIEF FINANCIAL OFFICER
IDEC PHARMACEUTICALS CORPORATION
11011 TORREYANA ROAD
SAN DIEGO, CA 92121
(619) 550-8500
(NAME AND ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER, INCLUDING AREA
CODE, OF AGENT FOR SERVICE)
------------------------

COPIES TO:

<TABLE>
<S> <C>
J. STEPHAN DOLEZALEK, ESQ. JAY K. HACHIGIAN, ESQ.
KIMBERLEY E. HENNINGSEN, ESQ. BRIAN K. BEARD, ESQ.
PETER D. ROSENTHAL, ESQ. RENEE F. LANAM, ESQ.
MATTHEW L. JACOBSON, ESQ. JONATHAN J. NOBLE, ESQ.
BROBECK, PHLEGER & HARRISON LLP GUNDERSON DETTMER STOUGH VILLENEUVE
TWO EMBARCADERO PLACE FRANKLIN & HACHIGIAN, LLP
2200 GENG ROAD 155 CONSTITUTION DRIVE
PALO ALTO, CA 94303 MENLO PARK, CA 94025
(650) 424-0160 (650) 321-2400
</TABLE>

------------------------

APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC:
As soon as practicable after this Registration Statement becomes effective.
------------------------

If the only securities being registered on this form are being offered
pursuant to dividend or interest reinvestment plans, please check the following
box: [ ]

If any of the securities being registered on this form are to be offered on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, other than securities offered only in connection with dividend or interest
reinvestment plans, check the following box: [ ]

If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering: [ ]
- ------

If this Form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. [ ]
- ------

If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box: [ ]

CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
PROPOSED MAXIMUM PROPOSED MAXIMUM
TITLE OF EACH CLASS OF AMOUNT TO BE OFFERING PRICE AGGREGATE AMOUNT OF
SECURITIES TO BE REGISTERED REGISTERED(1) PER SHARE(2) OFFERING PRICE REGISTRATION FEE
<S> <C> <C> <C> <C>
- -----------------------------------------------------------------------------------------------------------
Common Stock, $0.001 par value......... 2,300,000 shares $44.0625 $101,343,750 $30,711
===========================================================================================================
</TABLE>

(1) Includes 300,000 shares of Common Stock that the Underwriters have the
option to purchase to cover over-allotments, if any.

(2) Estimated solely for the purpose of computing the amount of the registration
fee in accordance with Rule 457(c) under the Securities Act of 1933.
------------------------

THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THE REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(A) OF
THE SECURITIES ACT OF 1933 OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE COMMISSION ACTING PURSUANT TO SAID SECTION 8(A)
MAY DETERMINE.
================================================================================
<PAGE> 2

INFORMATION CONTAINED HEREIN IS SUBJECT TO COMPLETION OR AMENDMENT. A
REGISTRATION STATEMENT RELATING TO THESE SECURITIES HAS BEEN FILED WITH THE
SECURITIES AND EXCHANGE COMMISSION. THESE SECURITIES MAY NOT BE SOLD NOR MAY
OFFERS TO BUY BE ACCEPTED PRIOR TO THE TIME THE REGISTRATION STATEMENT BECOMES
EFFECTIVE. THIS PROSPECTUS SHALL NOT CONSTITUTE AN OFFER TO SELL OR THE
SOLICITATION OF AN OFFER TO BUY NOR SHALL THERE BE ANY SALE OF THESE SECURITIES
IN ANY STATE IN WHICH SUCH OFFER, SOLICITATION OR SALE WOULD BE UNLAWFUL PRIOR
TO REGISTRATION OR QUALIFICATION UNDER THE SECURITIES LAWS OF ANY SUCH STATE.

PROSPECTUS (Subject to Completion)
Issued February 23, 1998

2,000,000 Shares

LOGO

COMMON STOCK
------------------------
ALL OF THE SHARES OF COMMON STOCK OFFERED HEREBY ARE BEING SOLD BY THE COMPANY.
THE COMPANY'S COMMON STOCK IS QUOTED ON THE NASDAQ NATIONAL MARKET UNDER THE
SYMBOL "IDPH." ON FEBRUARY 20, 1998, THE REPORTED LAST SALE PRICE OF THE COMMON
STOCK ON THE NASDAQ NATIONAL MARKET WAS $44 1/2 PER SHARE. SEE "COMMON STOCK
PRICE RANGE AND DIVIDENDS."

------------------------

SEE "RISK FACTORS" BEGINNING ON PAGE 6 FOR INFORMATION THAT SHOULD BE CONSIDERED
BY PROSPECTIVE INVESTORS.
------------------------
THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION, NOR HAS THE SECURITIES
AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.
------------------------
PRICE $ A SHARE
------------------------

<TABLE>
<CAPTION>
UNDERWRITING
PRICE TO DISCOUNTS AND PROCEEDS TO
PUBLIC COMMISSIONS(1) COMPANY(2)
---------------- ------------------- ---------------------
<S> <C> <C> <C>
Per Share............................ $ $ $
Total(3)............................. $ $ $
</TABLE>

- ------------

(1) The Company has agreed to indemnify the Underwriters against certain
liabilities, including liabilities under the Securities Act of 1933, as
amended.
(2) Before deducting expenses payable by the Company estimated at $275,000.
(3) The Company has granted the Underwriters an option, exercisable within
30 days of the date hereof, to purchase up to an aggregate of 300,000
additional Shares at the price to public less underwriting discounts and
commissions for the purpose of covering over-allotments, if any. If the
Underwriters exercise such option in full, the total price to public,
underwriting discounts and commissions and proceeds to Company will be
$ , $ and $ , respectively. See "Underwriters."

------------------------

The Shares are offered, subject to prior sale, when, as and if accepted by
the Underwriters named herein and subject to the approval of certain legal
matters by Gunderson Dettmer Stough Villeneuve Franklin & Hachigian, LLP,
counsel for the Underwriters. It is expected that delivery of the Shares will be
made on or about March , 1998 at the offices of Morgan Stanley & Co.
Incorporated, New York, N.Y., against payment therefor in same day funds.
------------------------

MORGAN STANLEY DEAN WITTER

NATIONSBANC MONTGOMERY SECURITIES LLC
March , 1998
<PAGE> 3

NO DEALER, SALES REPRESENTATIVE OR ANY OTHER PERSON HAS BEEN AUTHORIZED IN
CONNECTION WITH ANY OFFERING MADE HEREBY TO GIVE ANY INFORMATION OR TO MAKE ANY
REPRESENTATION OTHER THAN AS CONTAINED OR INCORPORATED BY REFERENCE IN THIS
PROSPECTUS AND, IF GIVEN OR MADE, SUCH INFORMATION OR REPRESENTATION MUST NOT BE
RELIED UPON AS HAVING BEEN AUTHORIZED BY THE COMPANY OR ANY UNDERWRITER. THIS
PROSPECTUS DOES NOT CONSTITUTE AN OFFER TO SELL OR A SOLICITATION OF AN OFFER TO
BUY ANY SECURITIES OTHER THAN THE SHARES OF COMMON STOCK OFFERED HEREBY, NOR
DOES IT CONSTITUTE AN OFFER TO SELL OR A SOLICITATION OF AN OFFER TO BUY ANY OF
THE SHARES OFFERED HEREBY TO ANY PERSON IN ANY JURISDICTION IN WHICH SUCH OFFER
OR SOLICITATION WOULD BE UNLAWFUL. NEITHER THE DELIVERY OF THIS PROSPECTUS NOR
ANY SALE MADE HEREUNDER SHALL UNDER ANY CIRCUMSTANCES CREATE ANY IMPLICATION
THAT THE INFORMATION CONTAINED HEREIN IS CORRECT AS OF ANY DATE SUBSEQUENT TO
THE DATE HEREOF.
------------------------
TABLE OF CONTENTS
<TABLE>
<CAPTION>
PAGE
----
<S> <C>
Incorporation of Certain Documents
by Reference............................. 2
Prospectus Summary......................... 3
Forward Looking Statements................. 6
Risk Factors............................... 6
Use of Proceeds............................ 17
Common Stock Price Range and Dividends..... 17
Capitalization............................. 18
Selected Consolidated Financial Data....... 19
Management's Discussion and Analysis of
Financial Condition and Results
of Operations............................ 20

<CAPTION>
PAGE
----
<S> <C>
Business................................... 26
Management................................. 46
Principal Stockholders..................... 50
Description of Capital Stock............... 52
Underwriters............................... 55
Legal Matters.............................. 56
Experts.................................... 56
Available Information...................... 57
Index to Consolidated Financial
Statements............................... F-1
</TABLE>

------------------------

INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

The following documents or portions of documents filed by the Company (File
No. 0-19311) with the Securities and Exchange Commission (the "SEC" or
"Commission") are incorporated herein by reference: (a) Annual Report on Form
10-K for the fiscal year ended December 31, 1996; (b) Proxy Statement dated
April 22, 1997 and (c) the description of the Company's Common Stock which is
contained in its Registration Statement on Form 8-A filed under the Securities
Exchange Act of 1934, as amended (the "Exchange Act"), on May 24, 1991, and the
description of the Company's Series X Junior Participating Preferred Stock
contained in the Company's Registration Statement on Form 8-A filed under the
Exchange Act on August 2, 1997, including any amendments or reports filed for
the purpose of updating such description.

All reports and other documents subsequently filed by the Company pursuant
to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act, prior to the filing
of a post-effective amendment which indicates that all securities offered hereby
have been sold or which deregisters all securities remaining unsold, shall be
deemed to be incorporated by reference herein and to be a part hereof from the
date of filing of such reports and documents. Any statement contained in a
document incorporated by reference herein shall be deemed modified or superseded
for purposes of this Prospectus to the extent that a statement contained or
incorporated by reference herein modifies or supersedes such statement. Any
statement so modified or superseded shall not be deemed, except as so modified
or superseded, to constitute a part of this Prospectus.

The Company will provide without charge to each person to whom this
Prospectus is delivered a copy of any or all of such documents which are
incorporated herein by reference (other than exhibits to such documents unless
such exhibits are specifically incorporated by reference into the documents that
this Prospectus incorporates). Written or oral requests for copies should be
directed to Secretary, IDEC Pharmaceuticals Corporation, at the Company's
executive offices located at 11011 Torreyana Road, San Diego, CA 92121; (619)
550-8500.
------------------------

IDEC Pharmaceuticals(R) and PRIMATIZED(R) are registered United States
trademarks of the Company and Rituxan(TM) and PROVAX(TM) are trademarks of the
Company. Other trademarks used herein belong to the various third parties as
identified in the text.
------------------------

CERTAIN PERSONS PARTICIPATING IN THIS OFFERING MAY ENGAGE IN TRANSACTIONS
THAT STABILIZE, MAINTAIN, OR OTHERWISE AFFECT THE PRICE OF THE COMMON STOCK.
SPECIFICALLY, THE UNDERWRITERS MAY OVERALLOT IN CONNECTION WITH THE OFFERING,
AND MAY BID FOR, AND PURCHASE, SHARES OF THE COMMON STOCK IN THE OPEN MARKET.
FOR A DESCRIPTION OF THESE ACTIVITIES, SEE "UNDERWRITERS."

IN CONNECTION WITH THIS OFFERING, CERTAIN UNDERWRITERS AND SELLING GROUP
MEMBERS (IF ANY) OR THEIR RESPECTIVE AFFILIATES MAY ENGAGE IN PASSIVE MARKET
MAKING TRANSACTIONS IN THE COMMON STOCK ON THE NASDAQ NATIONAL MARKET IN
ACCORDANCE WITH RULE 103 OF REGULATION M. SEE "UNDERWRITERS."

2
<PAGE> 4

PROSPECTUS SUMMARY

The following summary should be read in conjunction with, and is qualified
in its entirety by, the more detailed information and consolidated financial
statements and notes thereto appearing elsewhere herein or incorporated by
reference in this Prospectus. Unless otherwise indicated, the information
contained in this Prospectus assumes no exercise of the Underwriters'
over-allotment option. Unless the context otherwise requires, references in this
Prospectus to "IDEC Pharmaceuticals" and the "Company" shall refer to IDEC
Pharmaceuticals Corporation and its wholly owned subsidiary, IDEC Seiyaku, a
Japanese corporation.

THE COMPANY

IDEC Pharmaceuticals is primarily engaged in the commercialization and
research and development of targeted therapies for the treatment of cancer and
autoimmune and inflammatory diseases. The Company's first commercialized
product, Rituxan, and its most advanced product candidate are for treatment of
B-cell non-Hodgkin's lymphomas, which afflict approximately 250,000 patients in
the United States. The Company is also developing products for the treatment of
solid tumors, which afflict approximately 1,100,000 new patients each year in
the United States, and rheumatoid arthritis, which afflicts approximately
2,000,000 people in the United States.

Rituxan was approved by the U.S. Food and Drug Administration (the "FDA")
on November 26, 1997 and was launched into the U.S. market jointly with
Genentech, Inc. ("Genentech") in December 1997. Rituxan is the trade name in the
United States for the compound Rituximab (formerly known as IDEC-C2B8). In
Switzerland, and upon approval in the rest of Europe, Rituximab is marketed as
MabThera (Rituximab, Rituxan and MabThera are collectively referred to herein as
"Rituxan," except where otherwise indicated). Rituxan was developed through
collaborative relationships with Genentech and Genentech's affiliate F.
Hoffmann-LaRoche, Inc. ("Hoffmann-LaRoche") and is being developed for the
Japanese market in collaboration with Zenyaku Kogyo, Ltd. ("Zenyaku"). Rituxan
received Swiss marketing approval on November 28, 1997 and was recently
introduced in the Swiss market in late 1997 by Hoffmann-LaRoche, which holds
sales and marketing rights worldwide except in the United States and Japan.
Approval to market Rituxan in the European Union is currently pending and is not
expected before mid-1998, at the earliest. Zenyaku is developing Rituxan in
Japan where the regulatory process requires additional human clinical testing.
Approval in Japan is not expected in the near future.

Rituxan is the first monoclonal antibody approved by the FDA for a cancer
therapy indication. Rituxan is unique in the treatment of non-Hodgkin's lymphoma
due to its specificity for the antigen, CD20, which is expressed on normal and
malignant B cells but not on other tissues of the body, and mechanism of action
as compared to conventional lymphoma therapies. These properties of Rituxan also
contribute to the agent's favorable side effect profile as compared to
chemotherapy and allow its use in clinical settings where chemotherapy is either
poorly tolerated or ineffective in inducing disease remissions. Rituxan is
administered in an outpatient setting by personnel trained in the use of
chemotherapies. A full course of Rituxan therapy is short in duration,
consisting of four intravenous infusions given on days 1, 8, 15 and 22, whereas
chemotherapy is typically given in repeating cycles for four to eight months.

Rituxan is indicated for single agent use in relapsed or refractory,
low-grade or follicular, CD20 positive, B-cell non-Hodgkin's lymphomas ("B-cell
non-Hodgkin's lymphomas"), which comprise about half of the prevalence of the
disease in the United States. Ongoing or completed Phase II studies suggest that
Rituxan may also be useful in combination with chemotherapy in low-grade or
follicular lymphomas, and as a single agent, or in combination with chemotherapy
in the treatment of other forms of non-Hodgkin's lymphoma. In Phase III clinical
trials, Rituxan given as a single agent to patients with B-cell non-Hodgkin's
lymphoma, demonstrated tumor shrinkage in 87% of patients. Fifty percent of
evaluable patients (76 of 151 patients) or 48% of entered patients achieved
partial or complete responses to therapy, i.e., achieved tumor shrinkage of
greater than 50%. The median time to progression (time to tumor regrowth) in
these 76 responders had not been reached at 12.5 months following initiation of
therapy, despite the short duration (22 days) of the full course of therapy.
Rituxan has been well tolerated in clinical studies, with side effects being
primarily mild to moderate flu-like symptoms that generally are limited to the
period of infusion. As compared to

3
<PAGE> 5

chemotherapy, Rituxan does not harm the bone marrow and therefore does not cause
the myelosuppression that is a source of much of the chemotherapy-associated
morbidity and mortality. Also, Rituxan has been shown to induce meaningful
remissions of disease in poor prognosis patients such as the elderly, patients
failing autologous bone marrow transplants or anthracycline containing
therapies, and patients who have become refractory to chemotherapy.

In an effort to identify expanded applications for Rituxan, the Company, in
collaboration with Genentech, has authorized over 35 Rituxan post-marketing
trials to date. Several of these trials will explore the use of Rituxan in a
variety of B-cell non-Hodgkin's lymphoma clinical settings such as: combination
therapy with widely used chemotherapy regimens for both low-grade and
intermediate/high-grade disease; single agent therapy in newly diagnosed,
previously untreated low-grade disease; integration into autologous bone marrow
transplant regimens both as an in-vivo purging agent prior to bone marrow
harvest and post-transplant as consolidation therapy; and AIDS-related lymphoma.
Additionally, clinical trials are expected to be initiated in other B-cell
malignancies and pre-malignant conditions such as chronic lymphocytic leukemia
("CLL"), multiple myeloma, and lymphoproliferative disorders associated with
solid organ transplant therapies.

A second antibody product for the treatment of B-cell non-Hodgkin's
lymphomas, IDEC-Y2B8, which was opened to Phase III testing in December 1997.
IDEC-Y2B8 is an anti-CD20 murine antibody that is radiolabelled with the isotope
yttrium-90. IDEC Pharmaceuticals controls all U.S. rights to IDEC-Y2B8 while
Hoffmann-LaRoche holds an option to develop it for commercialization outside of
the United States. The Company believes that Rituxan and IDEC-Y2B8 may provide
complementary products for the management of non-Hodgkin's lymphomas.

The Company's product candidate for the treatment of solid tumors is the
drug 9-Aminocamptothecin ("9-AC"), which the Company in-licensed from Pharmacia
& Upjohn S.p.A. ("Pharmacia") in 1997. This drug belongs to the class of
anti-tumor agents that inhibits the activity of the enzyme topoisomerase-I,
which is required for solid tumor growth. The National Cancer Institute ("NCI")
was the primary developer of 9-AC through various Phase II human clinical
trials. The Company initiated its own Phase I/II trials with 9-AC during late
1997 with the objective of verifying the maximum tolerated dose identified by
other investigators and identifying solid tumor indications for further
development. IDEC Pharmaceuticals has worldwide rights to 9-AC.

For the treatment of autoimmune and inflammatory diseases, IDEC
Pharmaceuticals is developing a new class of antibodies, termed PRIMATIZED
antibodies, that are of part human, part macaque monkey, origin. These
antibodies are structurally similar to, and potentially indistinguishable by a
patient's immune system from, human antibodies. PRIMATIZED antibodies may
provide therapeutic intervention for diseases or conditions not amenable to
chronic treatment with mouse-derived antibodies, which are distinguishable from
human antibodies and therefore eventually rendered ineffective by the patient's
immune system. The Company's objective with its PRIMATIZED antibodies is to
provide therapies that can be used to control autoimmune diseases characterized
by overactive immune functions.

The Company's lead PRIMATIZED antibody products, IDEC-CE9.1 and IDEC-151,
are being developed worldwide in collaboration with SmithKline Beecham, p.l.c.
("SmithKline Beecham"), in patients with rheumatoid arthritis and asthma. The
Company's other products for the treatment of autoimmune or inflammatory
diseases are being developed in collaborative relationships with Mitsubishi
Chemical Corporation ("Mitsubishi"), Seikagaku Corporation ("Seikagaku") and
Eisai, Co., Ltd. ("Eisai"). In addition, the Company submitted an
Investigational New Drug application ("IND") with the FDA in late 1997 and
initiated human clinical testing in a Phase I trial of its humanized anti-gp39
antibody (IDEC-131) in patients with systemic lupus erythematosus ("SLE").

4
<PAGE> 6

THE OFFERING

<TABLE>
<S> <C>
Common Stock offered............................. 2,000,000 shares(1)
Common Stock to be outstanding after the
offering....................................... 21,630,694 shares(1)(2)
Use of proceeds.................................. To fund commercialization of Rituxan,
research and development activities and
clinical trials, expansion of laboratory
and manufacturing capacity, repayment of
indebtedness, and general corporate
purposes. A portion of the net proceeds
may also be used to acquire or invest in
complementary businesses or products or
to obtain the right to use complementary
technologies. See "Use of Proceeds."
Nasdaq National Market symbol.................... IDPH
</TABLE>

SUMMARY CONSOLIDATED FINANCIAL DATA

<TABLE>
<CAPTION>
YEARS ENDED DECEMBER 31,
--------------------------------------------------
1993 1994 1995 1996 1997
------- -------- -------- ------- --------
(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)
<S> <C> <C> <C> <C> <C>
CONSOLIDATED STATEMENT OF OPERATIONS DATA:
Revenues:
Revenues from unconsolidated joint
business(3)............................... $ -- $ -- $ -- $ -- $ 9,266
Contract revenues............................ 4,329 5,143 12,136 15,759 11,840
License fees................................. 8,385 2,300 11,500 14,250 23,500
-------- -------- -------- -------- --------
Total revenues.......................... 12,714 7,443 23,636 30,009 44,606
Total operating expenses(4).................... 22,985 25,959 40,037 35,445 62,602
Net loss applicable to common stock............ $(8,882) $(18,031) $(17,292) $(5,651) $(15,538)
Net loss per share............................. $ (.96) $ (1.65) $ (1.18) $ (.34) $ (.83)
Shares used in computing net loss per share.... 9,265 10,931 14,650 16,573 18,739
</TABLE>

<TABLE>
<CAPTION>
DECEMBER 31, 1997
---------------------------
ACTUAL AS ADJUSTED(5)
-------- --------------
(UNAUDITED)
(IN THOUSANDS)
<S> <C> <C>
CONSOLIDATED BALANCE SHEET DATA:
Cash, cash equivalents and securities available-for-sale........... $ 69,657 $153,042
Total assets....................................................... 106,013 189,398
Notes payable...................................................... 7,794 7,794
Total stockholders' equity......................................... 80,679 164,064
</TABLE>

- ------------

(1) Assumes the Underwriters' over-allotment option is not exercised. See
"Underwriters."

(2) Based on the number of shares outstanding as of January 31, 1998. Excludes:
(i) 3,902,619 shares of Common Stock issuable upon exercise of outstanding
stock options; and (ii) convertible preferred stock convertible into
1,490,793 shares of Common Stock, each outstanding as of January 31, 1998.

(3) Reflects revenues received from co-promotion of Rituxan with Genentech.

(4) Includes $11,437,000 in 1995 for the repurchase of technology rights to the
Company's lymphoma products and a $3,000,000 up-front licensing fee for
exclusive rights to 9-AC in 1997.

(5) Adjusted to reflect the sale of 2,000,000 shares offered by the Company
hereby, after deducting estimated underwriting discounts and commissions and
estimated offering expenses. See "Use of Proceeds" and "Capitalization."

5
<PAGE> 7

FORWARD LOOKING STATEMENTS

This Prospectus contains, in addition to historical data, forward-looking
statements within the meaning of Section 27A of the Securities Act of 1933, as
amended (the "Securities Act"), and Section 21E of the Exchange Act, which are
subject to the "safe harbor" created by those sections. These forward-looking
statements include risks and uncertainties and include, but are not limited to,
statements concerning the Company's plans to commercialize its product, Rituxan;
continue development of its current product candidates; conduct clinical trials
with respect to its product candidates; utilize the Company's capital resources
and the net proceeds from this offering and the time periods related thereto;
seek regulatory approvals; expand its manufacturing capability; engage
third-party manufacturers to supply its clinical trials and commercial
requirements; maintain and expand its marketing, sales and distribution
capability; and evaluate additional product candidates for acquisition and
subsequent clinical and commercial development. These forward-looking statements
may be found in the "Prospectus Summary," "Risk Factors," "Use of Proceeds,"
"Management's Discussion and Analysis of Financial Condition and Results of
Operations" and "Business." Forward-looking statements not specifically set
forth above may also be found in these and other sections of this Prospectus.
Actual results could differ materially from those discussed in the
forward-looking statements as a result of certain factors, including those
discussed in "Risk Factors" and elsewhere in this Prospectus.

RISK FACTORS

Prospective purchasers of the Shares offered hereby should carefully
consider the following risk factors in addition to the other information
presented in this Prospectus.

HISTORY OF OPERATING LOSSES; ACCUMULATED DEFICIT

The Company has incurred annual operating losses since its inception in
1985 and may incur additional losses in the future. As of December 31, 1997, the
Company's accumulated deficit was approximately $99.4 million. Historical losses
have been principally the result of the various costs associated with the
Company's research and development, clinical and manufacturing activities prior
to approval for marketing of any of the Company's products. Substantially all
revenues to date have resulted from collaborative research, development and
licensing arrangements, research grants and interest income. There is no
guarantee that the Company will achieve profitable operations on an annual basis
unless either Rituxan achieves commercial success or product candidates now
under development receive FDA or foreign regulatory approval and thereafter are
commercialized successfully.

Rituxan, which received regulatory approval in the United States on
November 26, 1997 and in Switzerland on November 28, 1997, is the Company's only
approved product. For Rituxan to succeed commercially, the Company, either alone
or through its collaborative relationships, must successfully manufacture,
introduce, market and sell Rituxan. To achieve the successful commercialization
of other product candidates, the Company, alone or through its collaborative
relationships, must successfully develop, obtain FDA or foreign regulatory
approval for, manufacture, introduce, market and sell its potential products.
There can be no assurance that either Rituxan or any other product candidate
will be successfully commercialized. See "Management's Discussion and Analysis
of Financial Condition and Results of Operations."

LIMITED MANUFACTURING EXPERIENCE

To be commercially successful, the Company must manufacture its products,
either directly or through third parties, in commercial quantities, in
compliance with regulatory requirements and at an acceptable cost. Although the
Company has produced its products in the laboratory, scaled its production
process to pilot levels and has the ability to manufacture limited commercial
quantities of Rituxan, the Company has only limited experience with regard to
producing such commercial quantities of Rituxan and has not yet received
regulatory approval for commercial production of any other products. In
addition, the Company has limited experience in bulk drug manufacturing in
general and no chemical manufacturing experience, no fill/finish experience, and
no fill/finish capacity. Thus, no assurance can be given as to the ultimate
performance of the Company's manufacturing facility or the Company's ability to
make a successful transition to ongoing commercial production.

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<PAGE> 8

Biologics manufacturing as performed by IDEC Pharmaceuticals involves the
growing and harvest of cells and the purification of the target protein by
removal of impurities in controlled environments. This process is extremely
susceptible to product loss due to any microbial or viral contamination of the
process. Since the process is highly defined and controlled, any material
problem due to equipment failure or operator error could cause the loss of the
entire batch being manufactured. Certain bacterial or viral contaminations could
cause the closure of the plant for an extended period of time, until the cause
of the contamination is identified and corrective action is implemented. Certain
items of manufacturing equipment may have long lead times to perform repair and
revalidation prior to use. The Company has attempted to plan for most equipment
failure contingencies. Not all potential problems, however, can be appropriately
addressed ahead of time nor spare parts obtained in a reasonable time frame. Any
extended unplanned plant shutdowns will ultimately create higher manufacturing
cost of goods for the Company and could result in inventory and product
shortages.

The Company's agreement with Genentech calls for IDEC Pharmaceuticals to
commit its full manufacturing capacity to supply Genentech with bulk Rituxan at
the higher of a fixed price per gram or Genentech's cost to manufacture per gram
until the end of 1999. The Company then has the option to supply Rituxan to
Genentech, at the lower of the Company's or Genentech's cost per gram. The
Company currently manufactures Rituxan at a cost in excess of the Genentech
contract's fixed price. Any continuing manufacturing costs above the contract
price per gram or costs attributable to equipment repair or facility down time
could result in an unreimburseable cost, wholly attributable to IDEC
Pharmaceuticals, which would, in turn, result in decreased margins. Furthermore,
the Company is aware that several of its manufacturing software systems are not
yet Year 2000 compliant. See "-- Year 2000 Compliance."

DEPENDENCE ON CONTRACT MANUFACTURERS AND SOLE SOURCE SUPPLIER

Although the Company has the ability to manufacture limited commercial bulk
quantities of Rituxan, it is dependent upon Genentech to manufacture additional
worldwide requirements and to complete all the fill/finish production of
Rituxan. Genentech is manufacturing Rituxan in a facility that is still pending
FDA approval for Rituxan manufacture and is currently constructing an additional
manufacturing plant to satisfy long-term demands for Rituxan. Such facility must
be approved by the FDA before it can supply commercial quantities of Rituxan
and, even if approved, there can be no assurance that the Company or Genentech
can manufacture sufficient quantities of Rituxan to meet as yet undetermined
market demands or that Genentech will be able to fill/finish Rituxan on a timely
and cost effective basis to avoid an insufficient supply of Rituxan inventory,
any of which could materially and adversely affect the Company's business,
results of operation and financial condition.

The Company is contractually dependent upon SmithKline Beecham to fulfill
all of the manufacturing requirements for IDEC-CE9.1 and IDEC-151. SmithKline
Beecham has constructed a commercial-scale manufacturing plant for IDEC-CE9.1
and/or IDEC-151. However, there can be no assurance that SmithKline Beecham will
be able to manufacture sufficient quantities of IDEC-CE9.1 or IDEC-151, should
either or both receive FDA approval to meet as yet undetermined market demands.

Because the Company's capacity is committed to the manufacture of Rituxan
for two years, the Company does not have the current cell culture capacity to
manufacture commercial qualifying material for the Company's IDEC-Y2B8 or In2B8
products. The Company is currently accepting proposals for a qualified
commercial contractor to meet the long-term manufacturing demands for IDEC-Y2B8
or In2B8. In addition, as the Company does not have expertise or facilities for
small molecule chemical manufacturing, the Company will need to establish a
long-term manufacturing arrangement for 9-AC with an appropriate contract
manufacturer. The Company's 9-AC clinical materials requirements will be met
over the next two years by Pharmacia, as part of the product in-license
agreement. Additionally, as the Company does not have fill/finish expertise, the
Company will be dependent on outside contractors to meet all of the Company's
current and future fill/finish requirements.

The Company has several vendors for raw materials that are used in the
manufacture of products for commercial or clinical trial use that are the sole
source available. Any disruption in the supply of these materials would have a
material adverse effect on the Company's ability to meet its manufacturing
commitments, and would ultimately have a negative effect on costs of goods sold,
or could delay significantly

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<PAGE> 9

current clinical studies. Due to the need for raw materials to meet certain
regulatory, pre-qualification and release specifications prior to their use for
manufacturing, the Company is limited to specific suppliers. The Company has
initiated a program for identifying alternative suppliers for certain raw
materials, where possible.

LIMITED SALES AND MARKETING EXPERIENCE

The Company has limited experience in commercial sales and marketing. The
Company has adopted a strategy of pursuing collaborative agreements with
strategic partners that provide for co-promotion of certain of the Company's
products. To the extent that the Company elects to participate in co-promotion
efforts in the United States or Canada, and in those instances where the Company
retains exclusive marketing rights in specified territories, the Company will
need to maintain and expand its sales and marketing capability in order to
establish a successful direct sales and marketing capability in the targeted
markets. The Company will also need to build marketing support services
including customer service, order entry, shipping and billing, customer
reimbursement assistance, managed-care sales support, medical information and
sales training. There can be no assurance that the Company will be able to
establish a successful direct sales and marketing capability in any or all
targeted markets or that it will be successful in gaining market acceptance for
its products. To the extent that the Company has entered or in the future enters
into co-promotion or other licensing arrangements, any revenues received by the
Company will be dependent on the efforts of third parties and there can be no
assurance that such efforts will be successful. Failure to establish a sales
capability either in the United States or outside the United States may have a
material adverse effect on the Company's business, results of operations and
financial condition. See "Business -- Sales and Marketing."

During 1998, the Company will depend on the successful marketing and sales
of Rituxan for much of its anticipated revenue. Rituxan is being marketed and
sold in the United States pursuant to a co-promotion agreement with Genentech,
which currently has a sales and marketing staff of approximately 50
professionals that is largely dedicated to the commercialization of Rituxan. In
an effort to establish its own direct sales capability for Rituxan, the Company
has recently created a marketing staff and a sales organization of 32
professionals with experience primarily in the oncology therapeutic category,
who are dedicated exclusively to the commercialization of Rituxan. The Company
relies heavily on Genentech to supply related marketing support services
including customer service, order entry, shipping and billing, customer
reimbursement assistance, managed-care sales support, medical information and
sales training. There can be no assurance that the Company's sales and marketing
staff will successfully transition the Company into long-term profitability.
Furthermore, there can be no assurance that Genentech will successfully perform
its role in the co-promotion relationship.

Outside of the United States and Canada, the Company has adopted a strategy
to pursue collaborative arrangements with established pharmaceutical companies
for marketing, distribution and sale of its products. There can be no assurance
that any of these companies or their sublicensees will successfully market,
distribute or sell the Company's products or that the Company will be able to
establish and maintain successful co-promotion or distribution arrangements.

OPERATING RESULTS SUBJECT TO SIGNIFICANT FLUCTUATIONS

The Company's quarterly revenues, expenses and operating results are likely
to vary significantly in the future due to a variety of factors such as demand
for the Company's products, the Company's achievement of certain payment
milestones, hospital and pharmacy buying decisions, physician acceptance rates,
changes in government or private reimbursement policies, manufacturing
constraints, the ability of the Company to obtain approvals of additional
products for commercial sale on a timely basis, changes in the Company's level
of operating expenses, the Company's ability to attract and retain qualified
personnel, changes in the Company's sales incentive plans or co-promotion
agreements, foreign currency exchange rates and overall economic conditions.
Furthermore, because the Company is commercializing Rituxan through a co-
promotion, profit-sharing agreement with Genentech, the Company's ability to
report revenues from the commercialization of Rituxan will be dependent upon the
timeliness of Genentech's reporting of Rituxan sales. There can be no assurance
that Genentech will report on a timely basis. Because the Company's expense
levels are based to a significant extent on the Company's expectations of future
revenues and therefore will

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<PAGE> 10

vary only slightly in the short term, if revenues fall below expectations,
operating results are likely to be adversely and disproportionately affected.

RELIANCE ON THIRD-PARTY DEVELOPMENT AND MARKETING EFFORTS

The Company has adopted a research, development and product
commercialization strategy that is dependent upon various arrangements with
strategic partners and others. The success of the Company's products is
substantially dependent upon the success of these outside parties in performing
their obligations, which include, but are not limited to, providing funding and
performing research and development with respect to the Company's products. The
Company's strategic partners may also develop products that may compete with the
Company. Although IDEC Pharmaceuticals believes that its partners have an
economic incentive to succeed in performing their contractual obligations, the
amount and timing of resources that they devote to these activities is not
within the control of the Company. There can be no assurance that these parties
will perform their obligations as expected or that any revenue will be derived
from such arrangements. The Company has entered into collaborative agreements
with Genentech, Zenyaku, SmithKline Beecham, Mitsubishi, Seikagaku and Eisai.
These agreements generally may be terminated at any time by the strategic
partner, typically on short notice to the Company. If one or more of these
partners elect to terminate their relationship with the Company, or if the
Company or its partners fail to achieve certain milestones, it could have a
material adverse effect on the Company's ability to fund the related programs
and to develop any products that may have resulted from such collaborations.
There can be no assurance that these collaborations will be successful. In
addition, some of the Company's current partners have certain rights to control
the planning and execution of product development and clinical programs, and
there can be no assurance that such partners' rights to control aspects of such
programs will not impede the Company's ability to conduct such programs in
accordance with the schedules currently contemplated by the Company for such
programs and will not otherwise impact the Company's strategy. See "Management's
Discussion and Analysis of Financial Condition and Results of Operations" and
"Business -- Strategic Alliances."

LENGTHY REGULATORY PROCESS; NO ASSURANCE OF ADDITIONAL REGULATORY APPROVALS

The testing, manufacturing, labeling, advertising, promotion, export and
marketing, among other things, of the Company's proposed products are subject to
extensive regulation by governmental authorities in the United States and other
countries. In the United States, pharmaceutical products are regulated by the
FDA under the Federal Food, Drug, and Cosmetic Act and other laws, including, in
the case of biologics, the Public Health Service Act. The nature and extent of
regulation by governmental authorities in the United States differs with respect
to different products. At the present time, with the exception of 9-AC, the
Company believes that its products will be regulated by the FDA as biologics.
Biologics require the submission of a Biologics License Application ("BLA") and
approval by the FDA prior to being marketed in the United States. The Company
believes that the FDA will regulate the Company's 9-AC product candidate as a
drug which will require the submission of a New Drug Application ("NDA") for
approval by the FDA prior to being marketed in the United States. The regulatory
approval process for a NDA is similar to the approval process for a BLA.
Manufacturers of biologics or drugs may also be subject to state regulation.

The steps required before a product may be approved for marketing in the
United States generally include (i) preclinical laboratory tests and animal
tests, (ii) the submission to the FDA of an IND for human clinical testing,
which must become effective before human clinical trials may commence, (iii)
adequate and well-controlled human clinical trials to establish the safety and
efficacy of the product, (iv) the submission to the FDA of a BLA or NDA, (v) FDA
review of the BLA or NDA and (vi) satisfactory completion of an FDA inspection
of the manufacturing facility or facilities at which the product is made to
assess compliance with current Good Manufacturing Practices ("cGMP"). The
testing and approval process requires substantial time, effort and financial
resources and there can be no assurance that any approval will be granted on a
timely basis, if at all. There can be no assurance that Phase I, Phase II or
Phase III testing will be completed successfully within any specific time
period, if at all, with respect to any of the Company's product candidates.
Furthermore, the FDA may suspend clinical trials at any time on various grounds,
including a finding that the subjects or patients are being exposed to an
unacceptable health risk.

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<PAGE> 11

The results of the preclinical studies and clinical study or studies,
together with detailed information on the manufacture and composition of the
product, are submitted to the FDA in the form of a BLA or NDA requesting
approval to market the product. Before approving a BLA or NDA, the FDA will
inspect the facilities at which the product is manufactured, and will not
approve the product unless cGMP compliance is satisfactory. The FDA may deny a
BLA or NDA if applicable regulatory criteria are not satisfied, require
additional testing or information, and/or require postmarketing testing and
surveillance to monitor the safety or efficacy of a product. There can be no
assurance that FDA approval of any BLA or NDA submitted by the Company will be
granted on a timely basis or at all. Also, if regulatory approval of a product
is granted, such approval may entail limitations on the indicated uses for which
it may be marketed.

Both before and after approval is obtained, violations of regulatory
requirements, including the preclinical and clinical testing process, the BLA or
NDA review process, or thereafter (including after approval) may result in
various adverse consequences, including the FDA's delay in approving or refusal
to approve a product, withdrawal of an approved product from the market, and/or
the imposition of criminal penalties against the manufacturer and/or BLA or NDA
holder. For example, BLA or NDA holders are required to report certain adverse
reactions to the FDA, and to comply with certain requirements concerning
advertising and promotional labeling for their products. Also, quality control
and manufacturing procedures must continue to conform to cGMP regulations after
approval, and the FDA periodically inspects manufacturing facilities to assess
compliance with cGMP. Accordingly, manufacturers must continue to expend time,
monies and effort in the area of production and quality control to maintain cGMP
compliance. In addition, discovery of problems may result in restrictions on a
product, manufacturer or BLA or NDA holder, including withdrawal of the product
from the market. Also, new government requirements may be established that could
delay or prevent regulatory approval of the Company's products under
development.

The Company will also be subject to a variety of foreign regulations
governing clinical trials and sales of its products. Whether or not FDA approval
has been obtained, approval of a product by the comparable regulatory
authorities of foreign countries must be obtained prior to the commencement of
marketing of the product in those countries. The approval process varies from
country to country and the time may be longer or shorter than that required for
FDA approval. At least initially, the Company intends, to the extent possible,
to rely on foreign licensees to obtain regulatory approval for marketing its
products in foreign countries.

In February 1997, the Company and Genentech submitted BLAs to the FDA for
Rituxan as a single agent therapy for the treatment of B-cell non-Hodgkin's
lymphoma, and on November 26, 1997, Rituxan was approved for marketing by the
FDA. Hoffmann-LaRoche submitted an application to the Swiss regulatory agency,
the Office Intercantonal de Controle de Medicaments, for the marketing of
Rituxan in Switzerland. On November 28, 1997, Rituxan was approved for marketing
in Switzerland and was launched in the Swiss market in late 1997 by
Hoffmann-LaRoche. Hoffmann-LaRoche also submitted a Marketing Authorization
Application ("MAA") with the European Medicines Evaluation Agency ("EMEA") for
marketing Rituxan in the European Union. There can be no assurance that EMEA
approval of the MAA will be granted on a timely basis, if at all, and delays in
receipt or failure to receive regulatory approval could have a material adverse
effect on the Company's business, results of operations and financial condition.

Under the Orphan Drug Act, the FDA may grant orphan drug designation to
drugs intended to treat a "rare disease or condition," which generally is a
disease or condition that affects fewer than 200,000 individuals in the United
States. Orphan drug designation must be requested before submitting a BLA or
NDA. After the FDA grants orphan drug designation, the generic identity of the
therapeutic agent and its potential orphan use are publicly disclosed by the
FDA. Orphan drug designation does not convey any advantage in, or shorten the
duration of, the regulatory review and approval process. If a product that has
an orphan drug designation subsequently receives FDA approval for the indication
for which it has such designation, the product is entitled to orphan drug
exclusivity, i.e., the FDA may not approve any other applications to market the
same drug for the same indication, except in certain very limited circumstances,
for a period of seven years.

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<PAGE> 12

be no assurance that IDEC-Y2B8 or IDEC-In2B8 will receive orphan drug
exclusivity for the B-cell non-Hodgkin's lymphoma indication, and it is possible
that competitors of the Company could obtain approval, and attendant orphan drug
exclusivity, for IDEC-Y2B8 or IDEC-In2B8 for the B-cell non-Hodgkin's lymphoma
indication, thus precluding the Company from marketing IDEC-Y2B8 or IDEC-In2B8
for that indication in the United States. In addition, even if the Company does
obtain orphan exclusivity for any of its compounds for B-cell non-Hodgkin's
lymphoma, there can be no assurance that competitors will not receive approval
of other, different drugs or biologics for B-cell non-Hodgkin's lymphoma.
Although obtaining FDA approval to market a product with orphan drug exclusivity
can be advantageous, there can be no assurance that the scope of protection or
the level of marketing exclusivity that is currently afforded by orphan drug
designation will remain in effect in the future.

UNCERTAINTIES ASSOCIATED WITH CLINICAL TRIALS

IDEC Pharmaceuticals has conducted and plans to continue to undertake
extensive and costly clinical testing to assess the safety and efficacy of its
potential products. The rate of completion of the Company's clinical trials is
dependent upon, among other factors, the rate of patient enrollment. Patient
enrollment is a function of many factors, including the nature of the Company's
clinical trial protocols, existence of competing protocols, size of the patient
population, proximity of patients to clinical sites and eligibility criteria for
the study. Delays in patient enrollment will result in increased costs and
delays, which could have a material adverse effect on the Company's business,
results of operations and financial condition. The Company cannot assure that
patients enrolled in the Company's clinical trials will respond to the Company's
product candidates. Setbacks are to be expected in conducting human clinical
trials. Failure to comply with the FDA regulations applicable to such testing
can result in delay, suspension or cancellation of such testing, and/or refusal
by the FDA to accept the results of such testing. In addition, the FDA may
suspend clinical trials at any time if it concludes that the subjects or
patients participating in such trials are being exposed to unacceptable risks.
Thus, there can be no assurance that Phase I, Phase II or Phase III testing will
be completed successfully within any specific time period, if at all, with
respect to any of the Company's potential products. Further, there can be no
assurance that human clinical testing will show any current or future product
candidate to be safe and effective or that data derived therefrom will be
suitable for submission to the FDA or will support the Company's submission of a
BLA or NDA. See "Business -- Government Regulation."

PATENTS AND PROPRIETARY RIGHTS

The Company's success will depend, in large part, on its ability to
maintain a proprietary position in its products through patents, trade secrets
and orphan drug designation. IDEC Pharmaceuticals owns by assignment seven
issued and 14 allowed U.S. patents, 16 U.S. patent applications and numerous
corresponding foreign patent applications, and has licenses to patents or patent
applications that are assigned to other entities. No assurance can be given,
however, that the patent applications of the Company or the Company's licensors
will be issued or that any issued patents will provide competitive advantages
for the Company's products or will not be successfully challenged or
circumvented by its competitors. Moreover, there can be no assurance that any
patents issued to the Company or the Company's licensors will not be infringed
by others or will be enforceable against others. In addition, there can be no
assurance that the patents, if issued, would not be held invalid or
unenforceable by a court of competent jurisdiction. Enforcement of the Company's
patents may require substantial financial and human resources. Moreover, the
Company or its licensees may have to participate in interference proceedings if
declared by the U.S. Patent and Trademark Office ("PTO") to determine priority
of inventions, which typically take several years to resolve and could result in
diminished scope of patent protection and substantial cost to the Company.

A substantial number of patents have already been issued to other
biotechnology and biopharmaceutical companies. Particularly in the monoclonal
antibody field, competitors may have filed applications for or have been issued
patents and may obtain additional patents and proprietary rights relating to
products or processes competitive with or similar to those of the Company. To
date, no consistent policy has emerged regarding the breadth of claims allowed
in biopharmaceutical patents. Moreover, United States and foreign country patent
laws are distinct and the interpretations thereunder unique to each country.
Thus, patentability, validity and infringement issues for the same technology or
invention may be resolved differently in different jurisdictions.

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<PAGE> 13

There can be no assurance that patents do not exist in the United States or in
foreign countries or that patents will not be issued that would have an adverse
effect on the Company's ability to market its products. Specifically, the
Company is aware of several patents and patent applications which may affect the
Company's ability to make, use and sell its products. See "Business -- Patents
and Proprietary Rights." Accordingly, the Company expects that commercializing
monoclonal antibody-based products may require licensing and/or cross-licensing
of patents with other companies or entities in this field. There can be no
assurance that the licenses, which might be required for the Company's processes
or products, would be available, if at all, on commercially acceptable terms.
The ability to license any such patents and the likelihood of successfully
contesting infringement, enforceability or validity of such patents are
uncertain and the costs associated therewith may be significant. If the Company
is required to acquire rights to valid and enforceable patents but cannot do so
at a reasonable cost, the Company's ability to manufacture or market its
products would be materially adversely affected.

The owners, or licensees of the owners, of these patents may assert that
one or more of the Company's products infringe one or more claims of such
patents. If legal action is commenced against the Company to enforce any of
these patents and the plaintiff in such action prevails, the Company could be
prevented from making, using, offering to sell, selling or importing the subject
matter claimed in such patents. In such event or under other appropriate
circumstances, the Company may attempt to obtain licenses to such patents.
However, no assurance can be given that any owner would license the patents to
the Company at all or on terms that would permit commercialization of the
Company's products. An inability to commercialize such products could have a
material adverse effect on the Company's business, results of operations and
financial condition.

Furthermore, the patent position worldwide of biotechnology companies in
relation to proprietary products is highly uncertain and involves complex legal
and factual questions. There is a substantial backlog of biotechnology patents
at the PTO. The Company also relies on trade secrets and proprietary know-how
which it seeks to protect, in part, by confidentiality agreements with its
employees, collaborators and consultants. There can be no assurance that these
agreements will not be breached, that the Company will have adequate remedies
for any breach, or that the Company's trade secrets will not otherwise become
known or be independently developed by competitors. See "Business -- Patents and
Proprietary Technology."

ADDITIONAL FINANCING REQUIREMENTS AND UNCERTAIN ACCESS TO CAPITAL MARKETS

The Company has expended and will continue to expend substantial funds to
increase sales of Rituxan and to complete the research, development,
manufacturing and marketing of its other products. The Company has obtained and
intends to seek additional funding for these purposes through a combination of
new collaborative arrangements, strategic alliances, and additional equity or
debt financings or from other sources. There can be no assurance that such
future additional funds will be available on acceptable terms, if at all. Even
if available, the cost of funds may result in substantial dilution to current
stockholders. If adequate funds are not available from operations or additional
sources of financing, the Company's business, results of operations and
financial condition could be materially and adversely affected. See
"Management's Discussion and Analysis of Financial Condition and Results of
Operations -- Liquidity and Capital Resources."

DEPENDENCE ON KEY PERSONNEL

The Company's success depends in part upon the continued contributions of
its senior management and key scientific and technical personnel. The Company's
success is also dependent upon its ability to attract and retain additional
qualified scientific, technical, manufacturing and managerial personnel and to
develop and maintain relationships with qualified clinical researchers.
Significant competition exists among pharmaceutical and biotechnology companies
for such personnel, and there can be no assurance that the Company will retain
such personnel or that it will be able to attract, assimilate and retain such
personnel as may be required in the future or to develop and maintain
relationships with such researchers. The Company does not maintain or intend to
purchase "key person" life insurance on any of its personnel. See
"Business -- Employees" and "Management."

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SUBSTANTIAL COMPETITION

Substantial competition exists in the biotechnology industry from
pharmaceutical and biotechnology companies which may have technical or
competitive advantages. The Company competes with these companies in the
development of technologies and processes and sometimes competes with them in
acquiring technology from academic institutions, government agencies, and other
private and public research organizations. There can be no assurance that the
Company will be able to produce or acquire rights to products that have
commercial potential. Even if the Company achieves product commercialization,
there can be no assurance that one or more of the Company's competitors may not:
(i) achieve product commercialization earlier than the Company, (ii) receive
patent protection that dominates or adversely affects the Company's activities,
(iii) have significantly greater sales and marketing capabilities or (iv)
develop products that are more widely accepted than those developed by the
Company. See "Business -- Competition."

VOLATILITY OF STOCK PRICE

The stock market has from time to time experienced significant price and
volume fluctuations that may be unrelated to the operating performance of
particular companies. In addition, the market price of the Company's Common
Stock, like the stock prices of many publicly traded biotechnology companies,
has been highly volatile. During 1997, the Company's stock price fluctuated
between $15 3/4 per share and $46 1/4 per share. Announcements of technological
innovations or new commercial products by the Company or its competitors,
developments or disputes concerning patent or proprietary rights, publicity
regarding actual or potential medical results relating to products or products
under development by the Company or its competitors, regulatory developments in
either the United States or foreign countries, public concern as to the safety
of biotechnology products and economic and other external factors including the
buying and selling of shares by option holders to offset their risk, as well as
period-to-period fluctuations in financial results may have a significant impact
on the market price of the Company's Common Stock. It is likely that in some
future quarter the Company's operating results will be below the expectations of
public market analysts and investors. In such event, the price of the Company's
Common Stock would likely be materially adversely affected. See "Common Stock
Price Range and Dividends" and "-- Outstanding Options; Possible Dilution and
Hedging."

UNCERTAINTIES REGARDING HEALTH CARE REIMBURSEMENT AND REFORM

The future revenues and profitability of biopharmaceutical companies as
well as the availability of capital may be affected by the continuing efforts of
government and third-party payors to contain or reduce costs of health care
through various means. For example, in certain foreign markets pricing or
profitability of prescription pharmaceuticals is subject to government control.
In the United States, there have been, and the Company expects that there will
continue to be, a number of federal and state proposals to implement similar
government controls. While the Company cannot predict whether any such
legislative or regulatory proposals will be adopted, the announcement or
adoption of such proposals could have a material adverse effect on the Company's
business, operating results and financial condition.

The Company's ability to commercialize its products successfully will
depend in part on the extent which appropriate reimbursement levels for the cost
of such products and related treatment are obtained from governmental
authorities, private health insurers and other organizations, such as health
maintenance organizations ("HMOs"). Third-party payors are increasingly
challenging the prices charged for medical products and services. Also, the
trend toward managed health care in the United States and the concurrent growth
of organizations such as HMOs, which could control or significantly influence
the purchase of health care services and products, as well as legislative
proposals to reform health care or reduce government insurance programs may all
result in lower prices for the Company's products. The cost containment measures
that health care payors and providers are instituting and the effect of any
health care reform could materially adversely affect the Company's business,
results of operations and financial condition. See "Business -- Pharmaceutical
Pricing and Reimbursement."

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The speed with which Rituxan is adopted into the marketplace will be
dependent on the rate of acceptance of the product into reimbursement programs
operated by governmental authorities, private health insurers and other
organizations, such as HMOs. Any significant delay in the ability of health-care
providers to receive reimbursement for Rituxan will similarly delay the adoption
of Rituxan and could have a material adverse effect on the Company's business,
operating results and financial condition.

PRODUCT LIABILITY EXPOSURE

Clinical trials, manufacturing, marketing and sale of any of the products
or products under development owned or licensed by the Company may expose the
Company to product liability claims. The Company currently carries limited
product liability insurance. There can be no assurance that the Company or its
strategic partners will be able to continue to maintain or obtain additional
insurance or, if available, that sufficient coverage can be acquired at a
reasonable cost. An inability to obtain sufficient insurance coverage at an
acceptable cost or otherwise protect against potential product liability claims
could prevent or inhibit the commercialization of pharmaceutical products
developed by the Company or its strategic partners. A product liability claim or
recall could have a material adverse effect on the Company's business, operating
results and financial condition.

ENVIRONMENTAL RISKS

The Company's business involves the controlled use of hazardous materials,
chemicals and radioactive compounds. Although the Company believes that its
safety procedures for handling and disposing of such materials comply with the
standards prescribed by state and federal regulations, the risk of accidental
contamination or injury from these materials cannot be completely eliminated. In
the event of such an accident, the Company could be held liable for any damages
that result and any such liability could exceed the resources of the Company. In
addition, disposal of radioactive materials used by the Company in its research
efforts may only be made at approved facilities. Approval of a site in
California has been delayed indefinitely. The Company currently stores such
radioactive materials on site. The Company may incur substantial cost to comply
with environmental regulations. See "Business -- Environmental Regulation."

SHARES ELIGIBLE FOR FUTURE SALE; REGISTRATION RIGHTS

Sales of substantial numbers of shares of Common Stock in the public market
following this offering could materially adversely affect the market price of
the Common Stock. Upon completion of this offering, the Company will have
outstanding 21,630,694 shares of Common Stock, all of which will be freely
tradeable in the public market, subject to limitations on sales of shares held
by "affiliates" of the Company as defined in Rule 144 promulgated under the
Securities Act. However, the executive officers, directors and certain other
stockholders of the Company, who will together hold 2,477,861 of the outstanding
shares upon completion of this offering, have agreed that for a period of 90
days from the date of this Prospectus and without the prior written consent of
Morgan Stanley & Co. Incorporated they will not (i) offer, pledge, lend, sell,
contract to sell, sell any option contract to purchase, purchase any option or
contract to sell, grant any option, right or warrant to purchase or otherwise
transfer, lend or dispose of, directly or indirectly, any shares of Common Stock
or any securities convertible into or exercisable or exchangeable for Common
Stock, or (ii) enter into any swap or other arrangement that transfers to
another, in whole or in part, any of the economic consequences of ownership of
the Common Stock, whether any such transaction described in clause (i) or (ii)
above is to be settled by delivery of Common Stock or such other securities, in
cash or otherwise. The Company has also agreed, subject to certain exceptions,
that without the prior written consent of Morgan Stanley & Co. Incorporated, it
will not issue, offer, sell or otherwise dispose of any of the Company's equity
securities or any other securities convertible into or exchangeable for the
Company's Common Stock for a period of 90 days after the date of this
Prospectus. However, the Company may, without such consent, grant options or
issue stock upon the exercise of outstanding stock options pursuant to the
Company's stock option plans. In addition, certain stockholders who in the
aggregate beneficially own 2,157,460 shares of Common Stock hold certain rights
with respect to the registration for the offer or sale to the public of such
shares. Upon completion

14
<PAGE> 16

of the offering, there will be outstanding options to purchase a total of
approximately 3,902,619 shares of the Company's Common Stock under the Company's
stock option plans. See "Description of Capital Stock."

EFFECT OF ANTI-TAKEOVER PROVISIONS

The Company has taken a number of actions that could have the effect of
discouraging a takeover attempt that might be beneficial to stockholders who
wish to receive a premium for their shares from a potential bidder. The Company
has adopted a Shareholder Rights Plan that would cause substantial dilution to a
person who attempts to acquire the Company on terms not approved by the
Company's Board of Directors. The Shareholder Rights Plan may therefore have the
effect of delaying or preventing any change in control and deterring any
prospective acquisition of the Company. In addition, the Company's Certificate
of Incorporation grants the Board of Directors the authority to issue up to
8,000,000 shares of Preferred Stock and to determine the price, rights,
preferences and privileges of those shares without any further vote or action by
the Company's stockholders. The rights of the holders of Common Stock will be
subject to, and may be adversely affected by, the rights of the holders of any
shares of Preferred Stock that may be issued in the future. While the Company
has no present intention to issue shares of Preferred Stock, such issuance,
while providing desirable flexibility in connection with possible acquisitions
and other corporate purposes, could have the effect of making it more difficult
or less attractive for a third party to acquire a majority of the outstanding
voting stock of the Company. Such Preferred Stock may also have other rights,
including economic rights senior to the Common Stock, and, as a result, the
issuance thereof could have a material adverse effect on the market value of the
Common Stock. Furthermore, the Company is subject to the anti-takeover
provisions of Section 203 of the Delaware General Corporation Law ("Section
203"), which prohibits the Company from engaging in a "business combination"
with an "interested stockholder" for a period of three years after the date of
the transaction in which the person first becomes an "interested stockholder,"
unless the business combination is approved in a prescribed manner. The
application of Section 203 also could have the effect of delaying or preventing
a change of control of the Company.

OUTSTANDING OPTIONS; POSSIBLE HEDGING AND DILUTION

In September 1997, the Company entered into an agreement with a financial
institution under which the Company sold to the financial institution a call
option, exercisable only at maturity, entitling the financial institution to
purchase from the Company up to 900,000 shares of the Company's Common Stock at
a certain strike price per share. The Company has the right to settle the call
option with cash or stock and, if exercised, the Company expects to settle the
call option by issuing up to 900,000 shares of the Company's Common Stock to the
financial institution. The financial institution has advised the Company that it
has engaged, and may continue to engage, in transactions, including buying and
selling shares of the Company's Common Stock, to offset its risk relating to the
call option, which could affect the market price of the Company's Common Stock.
Furthermore, should the Company settle the call option by issuing stock, new
investors will experience an immediate dilution at the time of issuance. Other
outstanding options and warrants will further dilute the Company's stock.

YEAR 2000 COMPLIANCE

Many currently installed computer systems and software products are coded
to accept only two digit entries in the date code field. Beginning in the year
2000, these date code fields will need to accept four digit entries to
distinguish 21st century dates from 20th century dates. As a result, in less
than two years, computer systems and software used by many companies may need to
be upgraded to comply with such "Year 2000" requirements.

Management has initiated an enterprise-wide program to prepare the
Company's computer systems and other electronic applications for the year 2000
(the "Year 2000 Program"). This Year 2000 Program, which is performed by a task
force assembled by the Company, consists of (i) an audit on all electronic and
computer systems in order to identify potential Year 2000 problems within the
Company, (ii) identification of third parties whose Year 2000 non-compliance
would have a material adverse effect on the Company's business, results of
operations or financial condition and requiring such third parties to confirm
that they are developing plans to address their own Year 2000 issues, and (iii)
a remedial phase to correct any discovered problems.

15
<PAGE> 17

The Company's Year 2000 Program has already identified several
manufacturing software systems that are not yet Year 2000 compliant. The Company
expects to complete its audit by the end of February 1998 and intends to
complete its third-party confirmations and begin its remedial phase by the end
of the third quarter. While the Company has begun evaluating potential
strategies for resolving Year 2000 problems, the dollar amount that the Company
will spend to remediate its Year 2000 issues remains uncertain, and management
has not yet assessed the Year 2000 compliance expenses and related potential
effect on the Company's operations. The Company expects to incur internal
personnel expenses as well as consulting and other expenses related to the
infrastructure and facilities enhancements necessary to prepare the Company's
systems for the year 2000.

The Company anticipates its Year 2000 Program will be completed before
January 1, 2000. However, there can be no assurance that the Year 2000 Program,
or computer systems and applications of other companies on which the Company's
operations rely, will be timely converted, or that any such failure to convert
by another company would not have a material adverse effect on the Company's
systems. Moreover, a failure to correct any non-compliant manufacturing software
could disable the Company's manufacturing capacity, resulting in inventory and
product shortages and ultimately creating higher manufacturing costs of goods of
the Company. See "-- Limited Manufacturing Experience."

16
<PAGE> 18

USE OF PROCEEDS

The net proceeds to the Company from the sale of the 2,000,000 shares of
Common Stock offered hereby are estimated to be approximately $83.4 million
($95.9 million if the Underwriters' over-allotment option is exercised in full)
after deducting underwriting discounts and commissions and estimated expenses of
the offering. The Company anticipates that the net proceeds of this offering
will be used to fund commercialization of Rituxan, research and development
activities and clinical trials, expansion of laboratory and manufacturing
capacity, repayment of indebtedness and general corporate purposes. A portion of
the net proceeds may also be used to acquire or invest in complementary
businesses or products or to obtain the right to use complementary technologies.
The Company has no current plans, agreements or commitments with respect to any
such acquisitions or investments, and the Company is not currently engaged in
any negotiations with respect to any such transactions. The use of proceeds is
subject to change based upon competitive developments, the rate of the Company's
progress in product sales and development, the timing of regulatory approval and
the availability of various methods of financing, including agreements with
other companies relating to the development and marketing of the Company's
products. The Company reserves the right, at the discretion of its Board of
Directors, to reallocate its use of the proceeds of this offering in response to
these and other factors. Pending such uses, the net proceeds will be temporarily
invested in investment-grade, interest-bearing marketable securities.

COMMON STOCK PRICE RANGE AND DIVIDENDS

The Company's Common Stock is traded on the Nasdaq National Market under
the symbol "IDPH." The following table sets forth for the periods indicated the
high and low reported sale prices as reported by the Nasdaq National Market.

<TABLE>
<CAPTION>
COMMON STOCK PRICE
-----------------------
HIGH LOW
--------- --------
<S> <C> <C> <C> <C>
Year Ended December 31, 1996
First Quarter............................................... $23 1/8 $15 7/8
Second Quarter.............................................. 32 5/8 21
Third Quarter............................................... 27 3/8 13 7/8
Fourth Quarter.............................................. 26 3/8 18 1/8
Year Ended December 31, 1997
First Quarter............................................... 30 3/4 19 7/8
Second Quarter.............................................. 27 1/8 15 3/4
Third Quarter............................................... 42 7/16 23 3/8
Fourth Quarter.............................................. 46 1/4 30 3/4
Year Ending December 31, 1998
First Quarter (through February 20, 1998)................... 45 1/4 32 3/4
</TABLE>

A recently reported last sale price for the Company's Common Stock as
reported on the Nasdaq National Market is set forth on the cover page of this
Prospectus. On January 31, 1998, there were approximately 429 holders of record
of the Company's Common Stock.

The Company has never declared or paid any cash dividends on the Common
Stock. The Company expects to retain its earnings for the development and
expansion of its business and, therefore, does not intend to pay dividends on
its Common Stock in the foreseeable future. Any future determination to pay cash
dividends will be at the discretion of the Company's Board of Directors and will
depend upon the earnings of the Company, its financial condition, capital
requirements and other factors as the Company's Board of Directors may deem
relevant.

17
<PAGE> 19

CAPITALIZATION

The following table sets forth the capitalization of the Company at
December 31, 1997, and as adjusted to reflect the sale by the Company of
2,000,000 shares of Common Stock pursuant to this offering (assuming that the
Underwriter's over-allotment option is not exercised).

<TABLE>
<CAPTION>
DECEMBER 31, 1997
------------------------
ACTUAL AS ADJUSTED
-------- -----------
(IN THOUSANDS)
<S> <C> <C>
Notes payable (1)..................................................... $ 7,794 $ 7,794

Stockholders' equity:
Convertible preferred stock, par value $0.001 per share, 8,000,000
shares authorized; 245,014 shares issued and outstanding,
$19,225,000 liquidation value, actual and as adjusted............
Common stock, par value $0.001 per share, 50,000,000 shares
authorized; 19,356,108 shares issued and outstanding, actual;
21,356,108 shares issued and outstanding, as adjusted (2)........ 19 21
Additional paid-in capital.......................................... 179,956 263,339
Unrealized gains on securities available-for-sale................... 57 57
Accumulated deficit................................................. (99,353) (99,353)
-------- --------
Total stockholders' equity.................................. 80,679 164,064
-------- --------
Total capitalization........................................ $ 88,473 $ 171,858
======== ========
</TABLE>

- ---------------
(1) See Note 4 of Notes to Consolidated Financial Statements for information
concerning the Company's notes payable.

(2) Assumes no exercise of the Underwriters' over-allotment option. Excludes:
(i) 3,948,341 shares of Common Stock issuable upon exercise of stock
options, and (ii) convertible preferred stock convertible into 1,665,793
shares of Common Stock, each outstanding as of December 31, 1997. See Note 8
of Notes to Consolidated Financial Statements.

18
<PAGE> 20

SELECTED CONSOLIDATED FINANCIAL DATA

The selected consolidated financial data presented below under the captions
"Consolidated Statement of Operations Data" and "Consolidated Balance Sheet
Data" for, and as of the end of, each of the years in the five-year period ended
December 31, 1997, are derived from the consolidated financial statements of the
Company, which consolidated financial statements have been audited by KPMG Peat
Marwick LLP, independent certified public accountants. The consolidated
financial statements as of December 31, 1996 and 1997, and for each of the years
in the three-year period ended December 31, 1997, and the report thereon, are
included elsewhere in this Prospectus. The information set forth below is not
necessarily indicative of the results of future operations and should be read in
conjunction with the Consolidated Financial Statements and related Notes thereto
that are included in this Prospectus and with "Management's Discussion and
Analysis of Financial Condition and Results of Operations."

<TABLE>
<CAPTION>
YEARS ENDED DECEMBER 31,
---------------------------------------------------
1993 1994 1995 1996 1997
-------- -------- -------- ------- --------
(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)
<S> <C> <C> <C> <C> <C>
CONSOLIDATED STATEMENT OF OPERATIONS DATA:
Revenues:
Revenues from unconsolidated joint
business................................. $ -- $ -- $ -- $ -- $ 9,266
Contract revenues........................... 4,329 5,143 12,136 15,759 11,840
License fees................................ 8,385 2,300 11,500 14,250 23,500
-------- -------- -------- -------- -------
Total revenues...................... 12,714 7,443 23,636 30,009 44,606
Operating expenses:
Manufacturing costs......................... -- -- -- -- 18,875
Research and development.................... 18,723 21,191 22,488 28,147 32,407
Selling, general and administrative......... 4,262 4,768 6,112 7,298 11,320
Acquired technology rights.................. -- -- 11,437 -- --
-------- -------- -------- -------- -------
Total operating expenses............ 22,985 25,959 40,037 35,445 62,602
-------- -------- -------- -------- -------
Loss from operations.......................... (10,271) (18,516) (16,401) (5,436) (17,996)
Interest income (expense), net................ 1,174 485 (891) 481 2,572
Other income (expense)........................ 215 -- -- -- (114)
Convertible preferred stock dividends......... -- -- -- (696) --
-------- -------- -------- -------- -------
Net loss applicable to common stock........... $ (8,882) $(18,031) $(17,292) $(5,651) $(15,538)
======== ======== ======== ======== =======
Net loss per share............................ $ (.96) $ (1.65) $ (1.18) $ (.34) $ (.83)
Shares used in computing net loss per
common share................................ 9,265 10,931 14,650 16,573 18,739
</TABLE>

<TABLE>
<CAPTION>
DECEMBER 31,
-------------------------------------------------
1993 1994 1995 1996 1997
------- ------- ------- -------- --------
(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)
<S> <C> <C> <C> <C> <C>
CONSOLIDATED BALANCE SHEET DATA:
Cash, cash equivalents and securities
available-for-sale............................ $26,503 $20,601 $24,010 $ 78,727 $ 69,657
Total assets.................................... 50,728 45,494 47,626 113,029 106,013
Notes payable................................... 4,697 11,062 9,846 8,845 7,794
Total stockholders' equity...................... 35,674 27,896 31,169 92,614 80,679
</TABLE>

19
<PAGE> 21

MANAGEMENT'S DISCUSSION AND ANALYSIS OF
FINANCIAL CONDITION AND RESULTS OF OPERATIONS

This Prospectus contains predictions, estimates and other forward-looking
statements within the meaning of Section 27A of the Securities Act of 1933, as
amended, and Section 21E of the Securities Exchange Act of 1934, as amended,
that involve a number of risks and uncertainties including, without limitation,
those set forth in "Risk Factors." While this outlook represents the Company's
current judgment on the future direction of its business, such risks and
uncertainties could cause actual results to differ materially from any future
performance suggested in this Management's Discussion and Analysis of Financial
Condition and Results of Operations.

The following discussion should be read in conjunction with the
Consolidated Financial Statements and related Notes thereto of IDEC
Pharmaceuticals appearing elsewhere in this Prospectus.

OVERVIEW

IDEC Pharmaceuticals is primarily engaged in the commercialization and
research and development of targeted therapies for the treatment of cancer and
autoimmune and inflammatory diseases. In November 1997, the Company received
approval from the FDA to market its first product, Rituxan, in the United States
and Hoffmann-LaRoche, the Company's European marketing partner, received
marketing clearance for Rituxan from the Swiss regulatory body, the Office
Intercantonal de Controle de Medicaments. Rituxan is being co-promoted in the
United States under a joint business arrangement with Genentech, with the
Company receiving a share of the pretax co-promotion operating results. Under
the terms of separate agreements with Genentech, commercialization of Rituxan
outside the United States will be the responsibility of Hoffmann-LaRoche, except
in Japan where Zenyaku will be responsible for product development, marketing
and sales. The Company will receive royalties on Rituxan sales outside the
United States.

Revenues for the Company consists of revenues from the unconsolidated joint
business with Genentech, contract revenues and license fees. To date a
substantial portion of the Company's revenues have been derived from contract
revenues and license fees and the Company anticipates that revenues from
unconsolidated joint business will comprise an increasing portion of total
revenues in the future resulting from the commercialization of Rituxan.

Revenues from unconsolidated joint business consists of the Company's share
of the pretax operating results generated from its joint business arrangement
with Genentech, revenue from bulk Rituxan sales to Genentech and reimbursement
from Genentech of the Company's sales force and development expenses. Revenues
also include royalty income from Hoffmann-LaRoche and Zenyaku on sales of
Rituxan outside the United States. Under the joint business arrangement, all
U.S. sales of Rituxan and associated expenses will be recognized by Genentech
with the Company recording its share of the pretax operating results on a
quarterly basis, as defined in the Company's collaborative agreement with
Genentech. "Pretax operating results" under the joint business arrangement are
derived by taking the net U.S. sales of Rituxan to third-party customers less
costs of sales, third party royalty expenses, distribution, selling and
marketing expenses and joint development expenses by the Company and Genentech.

Contract revenues consist of non-refundable research and development
funding under collaborative agreements with the Company's various strategic
partners and other funding under contractual arrangements with other parties.
Contract research and development funding generally compensates the Company for
discovery, preclinical and clinical expenses related to the collaborative
development programs for certain products of the Company.

License fees consist of non-refundable fees from product development
milestone payments, the sale of license rights to the Company's propriety gene
expression technology and non-refundable fees from the sale of product rights
under collaborative development and license agreements with the Company's
strategic partners.

The Company is obligated to manufacture and supply bulk Rituxan to
Genentech through the end of 1999 with an option to continue supplying Rituxan
thereafter. The cost of bulk Rituxan sold to Genentech is recorded as
manufacturing cost in the Company's consolidated statements of operations. Under
the

20
<PAGE> 22

Company's collaborative agreement with Genentech, the sales price of bulk
Rituxan sold to Genentech is capped at a price which is currently less than the
Company's cost to manufacture bulk Rituxan. See "Risk Factors -- Limited Sales
and Marketing Experience."

The Company has incurred increasing annual operating expenses and, with the
commercialization of Rituxan, the Company expects such trends to continue. The
Company has incurred annual operating losses since its inception in 1985, and
the transition of the Company to profitability will be dependent upon the
commercial success of Rituxan. As of December 31, 1997, the Company had an
accumulated deficit of $99.4 million. See "Risk Factors -- History of Operating
Losses; Accumulated Deficit."

RESULTS OF OPERATIONS

YEARS ENDED DECEMBER 31, 1997 AND 1996

Revenues from Unconsolidated Joint Business. The Company earned revenues
from unconsolidated joint business for the first time in 1997. Revenues from
unconsolidated joint business totaled $9.3 million in 1997 and consists of $10.6
million of bulk Rituxan sales to Genentech, $3.0 million in reimbursement for
the Company's sales force and development expenses for Rituxan from Genentech
and the Company's share of the joint business operating loss equaling $4.3
million. During 1997, the joint business recorded an operating loss due to
significant shared expenses related to the product launch of Rituxan in the
United States in December 1997. Rituxan sales to third-party customers recorded
by Genentech totaled $5.5 million, driven in part by pre-existing demand for
Rituxan upon launch in December 1997. The Company anticipates that revenues from
unconsolidated joint business will continue to increase in the near term due to
the commercialization of Rituxan.

Contract Revenues. Contract revenues totaled $11.8 million in 1997 compared
to $15.8 million in 1996. The decrease in contract revenues in 1997 was
primarily due to the completion of funding in 1996 under the Company's
collaborative development agreement with Mitsubishi Chemical Corporation.

License Fees. License fees totaled $23.5 million in 1997 compared to $14.3
million in 1996. The increase in license fees in 1997 was primarily due to a
$15.0 million product development milestone payment received from Genentech upon
FDA approval of Rituxan. License fee revenues can vary significantly from year
to year based upon the consummation of new corporate alliances and the
achievement of product development milestone events. The Company continues to
pursue other collaborative and license arrangements; however, no assurance can
be given that discussions in this regard will result in any such arrangements or
that the Company will receive significant revenues from any such collaborative
or license arrangements.

Manufacturing Costs. The Company incurred manufacturing costs for the first
time in 1997. Manufacturing costs totaled $18.9 million in 1997 and consisted of
manufacturing costs related to production of bulk Rituxan sold to Genentech and
includes costs of approximately $2.0 million incurred for the start-up of the
Company's manufacturing facility. The Company expects to continue incurring
substantial additional manufacturing costs as the Company continues to
manufacture bulk Rituxan.

Research and Development. Research and development expenses totaled $32.4
million in 1997 compared to $28.1 million in 1996. The increase in research and
development expenses in 1997 was primarily due to a $3.0 million up-front
licensing fee to Pharmacia for exclusive rights to 9-AC, a broad spectrum
anti-cancer agent, a license fee payment for Anti-MIF antibody technology
rights, contract manufacturing expenses for IDEC-Y2B8 in preparation for a Phase
III trial in 1998 and higher facility expenses. Research and development
expenses in 1997 were partially offset by the utilization of the Company's
manufacturing facility for bulk production of Rituxan inventory in 1997 compared
to research and development manufacturing production in 1996 of clinical
material used for clinical trials. The Company expects to continue incurring
substantial additional research and development expenses in the future, due to
expansion of research and development programs; technology inlicensing and
regulatory-related expenses; preclinical and clinical testing of the Company's
various products under development; and production scale-up and manufacturing of
products used in clinical trials.

21
<PAGE> 23

Selling, General and Administrative. Selling, general and administrative
expenses totaled $11.3 million in 1997 compared to $7.3 million in 1996. The
increase in selling, general and administrative expenses in 1997 was primarily
due to the creation of a sales and marketing infrastructure, expenses resulting
from the commercial launch of Rituxan and higher personnel expenses to support
expanded manufacturing operations. Selling, general and administrative expenses
necessary to support expanded manufacturing capacity, expanded clinical trials,
research and development and the potential expansion of the sales and marketing
organization are expected to increase in the foreseeable future.

Interest Income/Expense. Net interest income totaled $2.6 million in 1997
compared to $.5 million in 1996. The increase in net interest income in 1997 was
due to higher average balances in cash, cash equivalents and securities
available-for-sale, a decrease in noncash interest charges for common stock
warrants issued in connection with certain debt financings and a decrease in
interest expense due to lower balances in notes payable.

Income Taxes. IDEC Pharmaceuticals has incurred losses on an annualized
basis since inception; therefore, no provision for income taxes has been
recorded. The Company's net operating loss carryforwards available to offset
future taxable income at December 31, 1997 are approximately $82.0 million for
federal income tax purposes and expire between 1999 and 2012. The future
utilization of net operating loss carryforwards may be limited under the
Internal Revenue Code ("IRC") due to an IRC defined ownership change that
occurred during 1991. However, the Company believes that such limitations will
not have a material impact upon the utilization of the net operating loss
carryforwards.

YEARS ENDED DECEMBER 31, 1996 AND 1995

Contract Revenues. Contract revenues totaled $15.8 million in 1996 compared
to $12.1 million in 1995. The increase in contract revenues in 1996 was
primarily due to revenue from a collaboration entered into with Eisai in
December 1995, revenue from a one-time contract manufacturing and cell line
development arrangement with OraVax, Inc. and ongoing efforts under existing
collaborative agreements with Genentech and Seikagaku, offset by decreased
revenues from SmithKline Beecham as a result of the planned transfer of clinical
development of IDEC-CE9.1 to SmithKline Beecham in late 1995.

License Fees. License fees totaled $14.3 million in 1996 compared to $11.5
million in 1995. License fees in 1996 include $4.5 million received for the
license to Chugai of the Company's gene expression technology, $4.0 million
received from SmithKline Beecham for the initiation of a Phase III trial by
SmithKline Beecham of IDEC-CE9.1, $4.0 million from Genentech for the expansion
of its collaboration with the Company and for the achievement of a product
development milestone event for Rituxan and license fee revenues received from
Seikagaku and Eisai also for the achievement of product development milestone
events.

Research and Development. Research and development expenses totaled $28.1
million in 1996 compared to $22.5 million in 1995. The increase in research and
development expenses in 1996 was primarily due to a $1.3 million expense for
access to certain patent rights related to Rituxan, increased personnel costs
related to the completion of the Phase III trial, preparation of the Biologics
License Application and the preparation for building of Rituxan commercial
inventory.

Selling, General and Administrative. Selling, general and administrative
expenses totaled $7.3 million in 1996 compared to $6.1 million in 1995. Selling,
general and administrative expenses increased in 1996 due to higher personnel
costs to support expanded manufacturing operations, completion of the Phase III
trial and preparation of the Biologics License Applications for Rituxan.

Acquired Technology Rights. In March 1995, the Company issued 1,000,000
shares of its Common Stock and 69,375 shares of its 10% Series B Nonvoting
Cumulative Convertible Preferred Stock for the repurchase of all Merrill
Lynch/Morgan Stanley, L.P. rights in the Company's lymphoma products. In the
first quarter of 1995, the Company recorded a non-cash charge of $11.4 million,
representing the purchase of the acquired technology rights.

Interest Income/Expense. Net interest income totaled $.5 million in 1996
compared to net interest expense of $.9 million in 1995. The increase in net
interest income in 1996 from net interest expense in 1995

22
<PAGE> 24

was due to higher balances in cash, cash equivalents and securities
available-for-sale, offset by an increase in interest expense resulting from
increases in notes payable used to finance certain capital purchases and an
increase in non-cash interest charges for certain common stock warrants issued
in connection with certain debt financings.

LIQUIDITY AND CAPITAL RESOURCES

The Company has financed its operating and capital expenditures since
inception principally through the sale of equity securities, contract revenues,
license fees, lease financing transactions and interest income. The Company
expects to finance its current and planned operating requirements principally
through the proceeds of this offering, cash on hand, funds from its joint
business arrangement with Genentech and with funds from existing collaborative
agreements and contracts which the Company believes will be sufficient to meet
its near-term operating requirements. The Company believes that its cash,
including proceeds from this offering, cash equivalents and securities
available-for-sale, together with cash generated from its existing agreements,
contracts and joint business arrangement, will be sufficient to finance the
Company's currently anticipated needs for operating and capital expenditures for
the foreseeable future. Existing agreements and contracts, however, could be
canceled by the contracting parties. In addition, the Company may, from time to
time, seek additional funding through a combination of new collaborative
agreements, strategic alliances and additional equity and debt financings or
from other sources. There can be no assurance that such additional funds can be
obtained through these sources on acceptable terms, if at all. If adequate funds
are not available from the joint business arrangement, operations or additional
sources of financing, the Company's business could be materially and adversely
affected.

The Company's working capital and capital requirements will depend upon
numerous factors, including: the progress of the Company's preclinical and
clinical testing; fluctuating or increasing manufacturing requirements, research
and development programs; timing and cost of obtaining regulatory approvals;
levels of resources that the Company devotes to the development of
manufacturing, sales and marketing capabilities; technological advances; status
of competitors; and the ability of the Company to establish collaborative
arrangements with other organizations.

Until required for operations, the Company's policy under established
guidelines is to keep its cash reserves in bank deposits, certificates of
deposit, commercial paper, corporate notes, United States government instruments
and other readily marketable debt instruments, all of which are investment-grade
quality.

At December 31, 1997, the Company had $69.7 million in cash, cash
equivalents and securities available-for-sale compared to cash, cash equivalents
and securities available-for-sale of $78.7 million at December 31, 1996. Sources
of cash, cash equivalents and securities available-for-sale during 1997 include
$3.5 million from the issuance of common stock under employee stock option and
employee stock purchase plans and $3.0 million from funding under a loan to
finance equipment purchases. Uses of cash and cash equivalents during 1997
include $2.8 million used in operations, $5.9 million used to purchase capital
equipment, a $3.0 million preferred equity investment in Cytokine Networks, Inc.
("CNI") and $4.1 million used to pay notes payable.

In September 1997, the Company entered into an agreement with a financial
institution under which the Company purchased in a private transaction a capped
call option, exercisable only at maturity, representing the Company's right to
purchase from the financial institution up to 600,000 shares of the Company's
Common Stock. The Company has the right to settle the capped call option by
receiving cash or stock. The capped call option which the Company purchased is
expected to be settled, if exercised, with cash paid to the Company in an amount
equal to the difference between the strike price and the market price, subject
to caps which will limit the total amount of cash the Company could receive.

23
<PAGE> 25

institution. The financial institution has advised the Company that it has
engaged, and may continue to engage, in transactions, including buying and
selling shares of the Company's Common Stock, to offset its risk relating to the
call option, which could affect the market price of the Company's Common Stock.

In September 1997, the Company and CNI entered into a development and
license agreement for the development of inflammatory and autoimmune disease
products based upon CNI's Anti-MIF antibody technology and a stock purchase
agreement providing for certain equity investments in CNI by the Company. Under
the terms of these agreements, the Company may make payments totaling up to
$10.5 million, subject to the attainment of certain product development
milestone events. Additionally, the Company will pay CNI royalties on sales by
the Company of any products emerging from the collaboration. In 1997 the Company
made a $3.0 million preferred equity investment in CNI.

Under the terms of the 9-AC asset transfer agreement, the Company may make
payments to Pharmacia totaling up to $16.0 million, subject to the attainment of
certain product development milestone events. No royalties are payable to
Pharmacia on sales of any products commercialized by the Company emerging from
the agreement. The Company anticipates achieving a product development milestone
event in 1999 that would result in the Company making a $6.0 million payment to
Pharmacia.

In August 1995, the Company completed receipt of funding under a $10.0
million lease financing agreement to finance both equipment and facility
improvements. Terms of the financing agreement require final principal payments
of $1.1 million and $.4 million in July 1998 and January 1999, respectively.

NEW ACCOUNTING STANDARDS

In June 1997, the Financial Accounting Standards Board ("FASB") issued
Statement of Financial Accounting Standards No. 130 "Reporting Comprehensive
Income" ("Statement No. 130"). Statement No. 130 establishes standards for
reporting and display of comprehensive income and its components (revenue,
expenses, gains and losses) in a full set of general-purposes financial
statements. Statement No. 130 shall be effective for fiscal years beginning
after December 15, 1997 and requires reclassification of earlier periods
presented. The Company does not believe the adoption of Statement No. 130 will
have a significant impact on the Company's business, results of operations or
financial position for the year ending December 31, 1998.

In June 1997, the FASB issued Statement of Financial Accounting Standards
No. 131, "Disclosures about Segments of an Enterprise and Related Information"
("Statement No. 131"), effective for fiscal years beginning after December 15,
1997. Statement No. 131 establishes standards for reporting information about
operating segments in annual financial statements and selected information about
operating segments in interim financial reports issued to stockholders. The
Company does not believe the adoption of Statement No. 131 will have a
significant impact on the Company's financial statement disclosures.

YEAR 2000 COMPLIANCE

Many currently installed computer systems and software products are coded
to accept only two digit entries in the date code field. Beginning in the year
2000, these date code fields will need to accept four digit entries to
distinguish 21st century dates from 20th century dates. As a result, in less
than two years, computer systems and/or software used by many companies may need
to be upgraded to comply with such "Year 2000" requirements.

Management has initiated its Year 2000 Program, which has already
identified several manufacturing software systems that are not yet Year 2000
compliant. The Company expects to complete its audit by the end of February and
intends to complete its third-party confirmations and begin its remedial phase
by the end of the third quarter. While the Company has begun evaluating
potential strategies for resolving Year 2000 problems, the dollar amount that
the Company will spend to remediate its Year 2000 issues remains uncertain, and
management has not yet assessed the Year 2000 compliance expenses and related
potential effect on the Company's operations. The Company expects to incur
internal personnel expenses as well as consulting and

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<PAGE> 26

other expenses related to the infrastructure and facilities enhancements
necessary to prepare the Company's systems for the year 2000.

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BUSINESS

IDEC Pharmaceuticals is primarily engaged in the commercialization and
research and development of targeted therapies for the treatment of cancer and
autoimmune and inflammatory diseases. The Company's first commercial product,
Rituxan, and its most advanced product candidate are for treatment of B-cell
non-Hodgkin's lymphomas, which afflict approximately 250,000 patients in the
United States. The Company is also developing products for the treatment of
solid tumors, which afflict approximately 1,100,000 new patients each year in
the Unites States, and rheumatoid arthritis, which afflicts approximately
2,000,000 people in the United States.

BACKGROUND

ANTIBODIES AND THE IMMUNE SYSTEM

The immune system is composed of specialized cells, including B cells and T
cells, that function in the recognition, destruction and elimination of disease
causing foreign substances and of virally infected or malignant cells. The role
of these specialized cells is determined by receptors on the cell surface which
govern the interaction of the cell with foreign substances and with the rest of
the immune system. For example, each differentiated B cell of the immune system
has a different antibody anchored to its surface that serves as a receptor to
recognize foreign substances. This antibody then triggers the production of
additional antibodies which as free-floating molecules bind to and eliminate
these foreign substances. Each foreign substance is individually identifiable by
structures on its surface known as antigens, which serve as binding sites for
the specific antibodies. T cells play more diverse roles, including the
identification and destruction of virally infected or malignant cells.

A variety of technologies have been developed to produce antibodies as
therapeutic agents. These include hybridoma technology and molecular biology
techniques such as gene cloning and expression, which can now be applied to the
generation, selection and production of hybrid monoclonal antibody varieties
known as chimeric and humanized antibodies, as well as strictly human
antibodies. Chimeric antibodies are constructed from portions of non-human
species (e.g., mouse) antibodies and human antibodies. In these applications,
the portion of the antibody responsible for antigen binding (the "variable
region") is taken from a non-human antibody and the remainder of the antibody
(the "constant region") is taken from a human antibody. Compared to mouse
("murine") monoclonal antibodies, chimeric antibodies generally exhibit lower
immunogenicity (the tendency to trigger an often adverse immune response such as
a human anti-mouse antibody, or "HAMA" response), are cleared more slowly from
the body, and function more naturally in the human immune system. Humanized
antibodies can be constructed by grafting several small pieces of a murine
antibody's variable region onto a constant region framework provided by a human
antibody. This process, known as "CDR grafting," reduces the amount of foreign
materials in the antibody, rendering it closer to a human antibody. However, the
construction of humanized antibodies by CDR grafting requires complex computer
modeling, and the properties of the resulting antibody are not completely
predictable and may, in fact, still trigger a HAMA response.

B-CELL NON-HODGKIN'S LYMPHOMAS

As with other cell types in the body, B cells and T cells may become
malignant and grow as immune system tumors, such as lymphomas. B-cell
non-Hodgkin's lymphomas are cancers of the immune system which currently afflict
approximately 250,000 patients in the United States. Treatment alternatives for
lymphoma patients include chemotherapy, radiation therapy, and more recently,
the Company's Rituxan that is indicated for use in relapsed or refractory,
low-grade or follicular, CD20 positive, B-cell non-Hodgkin's lymphoma. B-cell
non-Hodgkin's lymphomas are diverse with respect to prognosis and treatment, and
are generally classified into one of three groups (low, intermediate or
high-grade) based on histology and clinical features. These three groups are
further subdivided by the International Working Formulation ("IWF") into
subclasses A through J: low grade (A, B and C); intermediate grade (D, E, F and
G); and high grade (H, I and J). Low grade or follicular B-cell non-Hodgkin's
lymphoma is comprised of IWF subclasses A through D. The Company estimates that
approximately half of the 250,000 patients afflicted with B-cell non-Hodgkin's

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<PAGE> 28

lymphoma in the United States have low grade or follicular disease; of these
roughly 18,000 will have been diagnosed during the past 12 months. Patients with
low-grade lymphomas have a fairly long life expectancy from the time of
diagnosis (median survival 6.6 years), despite the fact that low-grade lymphomas
are almost always incurable. Intermediate-grade and high-grade lymphomas are
more rapidly growing forms of these cancers, which in a minority of cases can be
cured with early, aggressive chemotherapy. New diagnoses of non-Hodgkin's
lymphomas have increased approximately 5.9% annually over the past decade, with
55,400 new diagnoses estimated for 1998. The increase is due in part to the
aging of the population and to the increasing prevalence of lymphomas in the
AIDS patient population. In approximately 90% of the cases in the United States,
non-Hodgkin's lymphomas are of B-cell origin, the remainder is of T-cell origin.

Owing to the fluid nature of the immune system, B-cell lymphomas are
usually widely disseminated and characterized by multiple tumors at various
sites throughout the body at first presentation. Treatment courses with
chemotherapy or radiation therapy often result in a limited number of remissions
for patients with B-cell lymphomas. The majority of patients in remission will
relapse and ultimately die either from their cancer or from complications of
standard therapy. Fewer patients achieve additional remissions following relapse
and those remissions are generally of shorter duration as the tumors become
increasingly resistant to subsequent courses of chemotherapy. Therapeutic
product development efforts for these cancers have focused on both improving
treatment results and minimizing the toxicities associated with standard
treatment regimens. Immunotherapies with low toxicity and demonstrated efficacy,
such as Rituxan, might be expected to reduce treatment and hospitalization costs
associated with side effects or opportunistic infections, which can result from
the use of chemotherapy and radiation therapy.

AUTOIMMUNE AND INFLAMMATORY DISEASES

Rheumatoid arthritis, SLE, psoriasis, inflammatory bowel disease ("IBD")
and multiple sclerosis ("MS") are autoimmune and inflammatory diseases that
require ongoing therapy and afflict more than 6 million patients in the United
States. Of these, approximately 2 million people are afflicted with rheumatoid
arthritis. Autoimmune disease occurs when the patient's immune system goes awry,
initiating a cascade of events which results in an attack by the patient's
immune system against otherwise healthy tissue and often includes inflammation
of the involved tissue. In rheumatoid arthritis, the disease attacks the
synovial lining of the patient's joints, usually resulting in the destruction of
the joints of the hands, hips and knees. The patient's condition evolves from
constantly painful joints to the disability of deformed, misaligned joints.
Autoimmune diseases such as rheumatoid arthritis are typically treated with
products such as steroids and nonsteroidal, anti-inflammatory agents and with
other therapies, all of which are limited for several reasons, including their
lack of specificity and ineffectiveness when used chronically. Furthermore,
steroids suppress the immune system and make the patient susceptible to
infections while nonsteroidal, anti-inflammatory agents have been implicated in
the formation of gastro-intestinal ulcerations.

ANTIBODIES AND THE REGULATION OF IMMUNE SYSTEM CELLS

Monoclonal antibodies may be used to bind to specific subsets of human
immune system cells and may act to deplete or to suppress the activity of the
targeted cells. Indeed, the high specificity of monoclonal antibodies enable
them to discriminately act against different types of B cells or T cells.
Depletion of diseased immune cells or suppression of disease-causing immune
activities may be possible by using antibodies that attach to specific
determinants on the surface of target immune system cells. In particular, the
individual B and T cells of the immune system express a broad variety of surface
determinants (cell surface markers). Such determinants not only differentiate
one cell type from another, but also differentiate individual cells from other
cells with specificity for different antigens. Monoclonal antibodies may also be
used to bind to molecules, such as cytokines, in the plasma which serve as
soluble mediators of immune system cell activity. By neutralizing these
molecules, monoclonal antibodies may be used to alter immune cell activity
and/or migration, for example, in inflammatory conditions.

IDEC PHARMACEUTICALS' TECHNOLOGY

IDEC Pharmaceuticals is developing products for the management of immune
system cancers, solid tumors and autoimmune and inflammatory diseases. The
Company's antibody products bind to specific

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subsets of human immune system cells, or to soluble mediators of immune cell
activity, and act to deplete or to alter the activity of these cells. The
products are administered intravenously and target cells or soluble mediators
located in easily accessible compartments of the body, specifically the blood,
the lymphatic fluid and the synovial fluid. For treatment of non-Hodgkin's
B-cell lymphomas, the Company's products target a cell surface marker known as
CD20 which is present only on B cells but not on B-cell precursors. These
products act to reduce total B-cell levels, including both malignant and normal
B cells. The depletion of normal B cells observed in clinical experience to date
has been only temporary, with regeneration occurring within months. The Company
believes that its recently launched product, Rituxan, and the successful
development of radioimmunotherapeutic agents, such as IDEC-Y2B8, will provide
therapeutic alternatives to complement and, in some cases, replace
chemotherapeutic agents in the treatment of B-cell non-Hodgkin's lymphomas.

Due to their specificity and affinity for cell surface receptors,
monoclonal antibodies are also an attractive means by which to treat autoimmune
diseases. Attachment of monoclonal antibodies to specific cell surface receptors
can be used to suppress aberrant and unwanted immune activity. Historically,
however, the use of monoclonal antibodies as an ongoing therapy has been limited
by the body's rejection of the mouse derived components of the antibodies.
Murine monoclonal antibodies, which are structurally different from human
antibodies, tend to trigger adverse immune reactions when used as therapies.
These reactions include a HAMA response in which the patient's immune system
produces antibodies against the therapeutic antibody, thus limiting its
effectiveness.

The Company has developed a proprietary PRIMATIZED antibody technology
designed to avoid HAMA responses and other immunogenicity problems by developing
monoclonal antibodies from primate rather than mouse B cells. These antibodies
are characterized by their strong similarity to human antibodies and by the
absence of mouse components. In March 1996, the Company received a Notice of
Allowance for a United States patent application claiming the Company's
PRIMATIZED antibodies. Underlying this proprietary technology is the Company's
discovery that macaque monkeys produce antibodies that are structurally
indistinguishable from human antibodies in their variable (antigen-binding)
regions. Further, the Company found that the macaque monkey can be immunized to
make antibodies that react with human, but not with macaque, antigens. Genetic
engineering techniques are then used to isolate the portions of the macaque
antibody gene that encode the variable region from a macaque B cell. This
genetic material is combined with constant region genetic material from a human
B cell and inserted into a host cell line which then expresses the desired
antibody specific to the given antigen. The result is a part human, part macaque
PRIMATIZED antibody which appears structurally to be so similar to human
antibodies that it may be accepted by the patient's immune system as "self."
This development allows the possibility of therapeutic intervention in chronic
diseases or other conditions that are not amenable to treatment with antibodies
containing mouse components.

The Company has also discovered a proprietary antigen formulation, PROVAX,
which has shown the ability to induce cellular immunity, manifested by cytotoxic
T lymphocytes, in animals immunized with protein antigens. Cellular immunity is
a counterpart to antibody-based immunity and is responsible for the direct
destruction of virally infected and malignant cells. PROVAX is a combination of
defined chemical entities and may provide a practical means for the development
of effective immunotherapies that act through the induction of both antibody and
cell-mediated immunity. The Company believes such immunotherapies may be useful
for the treatment of certain cancers and viral diseases. Preliminary studies
also indicate that PROVAX can be safely administered by injection to human
subjects. The Company intends to make PROVAX available through licenses and
collaborations to interested partners for development of immunotherapeutic
vaccines.

IDEC Pharmaceuticals has developed methods of engineering mammalian cell
cultures using proprietary gene expression technologies (its "vector
technologies") that rapidly and reproducibly select for stable cells, producing
high levels of desired proteins. These technologies allow the efficient
production of proteins at yields that may be significantly higher, and costs
that may be significantly lower, than current, competing cell culture methods.
IDEC Pharmaceuticals has successfully applied one of these technologies to the
commercial scale production of Rituxan.

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PRODUCTS AND PRODUCTS UNDER DEVELOPMENT

Rituxan and the Company's primary products under development address immune
system cancers, such as lymphomas, solid tumors, and autoimmune and inflammatory
diseases, such as rheumatoid arthritis. In addition, the Company has discovered
certain other products through the application of its technology platform. The
products in preclinical and clinical development by the Company include the
following.

<TABLE>
<S> <C> <C> <C>
- ------------------------------- INDICATION STATUS(1) DEVELOPMENT/MARKETING
------------------------- ------------------------- -------------------------
IMMUNE SYSTEM CANCER PRODUCTS:
Rituxan........................ Certain B-cell non- U.S.: Approved Genentech (U.S.
Hodgkin's lymphomas co-promotion)
European Union: MAA Hoffmann-LaRoche
pending
Switzerland: Approved Hoffmann-LaRoche
Japan: Phase II Zenyaku
IDEC-Y2B8...................... Certain B-cell non- Phase III Hoffmann-LaRoche (option
Hodgkin's lymphomas to commercialize outside
(radioimmunotherapy) the U.S.)
IDEC-In2B8..................... Certain B-cell non- Phase III Hoffmann-LaRoche (option
Hodgkin's lymphomas to commercialize outside
(tumor imaging and the U.S.)
dosimetry)
9-AC........................... Solid tumors Phase I/II No current partner
AUTOIMMUNE AND INFLAMMATORY PRODUCTS:
PRIMATIZED IDEC-151............ Rheumatoid arthritis Phase II portion of Phase I/II SmithKline Beecham
(worldwide)
PRIMATIZED IDEC-CE9.1.......... Rheumatoid arthritis Phase III - On Clinical SmithKline Beecham
Hold (worldwide)
PRIMATIZED IDEC-CE9.1.......... Asthma Phase I - On Clinical SmithKline Beecham
Hold (worldwide)
Humanized Anti-gp39 Various autoimmune Phase I Eisai (Europe and Asia)
(IDEC-131)................... diseases, initially SLE
PRIMATIZED Anti-gp39........... Various autoimmune Lead compound selected Eisai (Europe and Asia)
diseases
PRIMATIZED Anti-B7............. Various autoimmune Preclinical development Mitsubishi (Asia)
diseases, initially
psoriasis
PRIMATIZED Anti-CD23........... Various allergic Lead compound selected Seikagaku (Europe and
conditions, initially Asia)
allergic asthma
Humanized and PRIMATIZED
Anti-MIF..................... Various Inflammatory Discovery No current partner
conditions
OTHER PRODUCTS:
PROVAX (antigen formulation)... Cancer therapeutic Phase I(2) No current partner
vaccines
</TABLE>

- ---------------

(1) As used in this Prospectus, "Discovery" means that the research phase is
ongoing and a lead compound has not yet been selected. "Lead compound
selected" means agents have been identified that meet preselected criteria
in assays for activity and potency. "Preclinical development" means lead
compound undergoing testing required prior to submission of IND. "Phase I"
means initial human studies designed to establish the safety, dose tolerance
and pharmacokinetics of a compound. "Phase I/II" means initial human studies
designed to establish the safety, dose tolerance and pharmacokinetics of a
compound and which may be designed to show preliminary activity of a
compound in patients with the targeted disease. "Phase II" means human
studies designed to establish safety, optimal dosage and preliminary
activity of a compound. "Phase III" means human studies designed to lead to
accumulation of data sufficient to support a BLA, including data relating to
efficacy. For a further description of "On Clinical Hold," see "-- Products
and Products Under Development -- Autoimmune and Inflammatory
Products -- PRIMATIZED IDEC-151 and IDEC-CE9.1.

(2) Although Phase I trials have been completed, the Company does not intend to
pursue further development unless and until it enters into a partnering
arrangement for such development.

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<PAGE> 31

IMMUNE SYSTEM CANCER PRODUCTS

IDEC Pharmaceuticals' objective with respect to treating non-Hodgkin's
B-cell lymphomas is to use its pan-B antibodies to target, bind to and
selectively eliminate both the patient's normal and malignant B cells.

Rituxan. Rituxan is a genetically engineered, chimeric murine, human
monoclonal antibody designed to harness the patient's own immune mechanisms to
destroy tumor cells. Rituxan was approved by the FDA for treatment of certain
B-cell non-Hodgkin's lymphomas. Rituxan has also been approved in Switzerland
and other European approvals are pending. Laboratory studies performed by the
Company have shown that the antibody attaches to the CD20 antigen on B cells and
activates a group of proteins known as "complement," leading to normal and
malignant B-cell destruction. Additionally, the antibody, when bound to the CD20
antigen, recruits macrophages and natural killer cells to attack the B cell.
Through these and other mechanisms, the antibody utilizes the body's immune
defenses to lyse (rupture) and deplete B cells. B cells have the capacity to
regenerate from early precursor cells that do not express the CD20 determinant.
The depletion of normal B cells observed in clinical experience to date has been
only temporary, with normal B-cell regeneration typically occurring within six
to nine months. The capacity of a tumor to regrow after treatment with Rituxan
will depend on the number of malignant B cells, or malignant B-cell precursors
(if the malignancy first appeared within a precursor cell), remaining after
treatment.

Rituxan is the first monoclonal antibody approved by the FDA for a cancer
therapy indication. Rituxan is unique in the treatment of non-Hodgkin's lymphoma
due to its specificity for the antigen, CD20, which is expressed only on normal
and malignant B cells, but not on other tissues of the body, and mechanism of
action as compared to conventional lymphoma therapies. These properties of
Rituxan contribute to the agent's favorable side effect profile as compared to
chemotherapy and allows its use in clinical settings where chemotherapy is
either poorly tolerated or ineffective in inducing disease remissions. Rituxan
is easily administered in the outpatient setting by personnel trained in the use
of chemotherapies. A full course of Rituxan therapy consists of four intravenous
infusions given on days 1, 8, 15 and 22, whereas chemotherapy is given typically
in repeating cycles for up to four to eight months.

Rituxan is indicated for single agent use in relapsed or refractory, low
grade or follicular, CD20 positive, B-cell non-Hodgkin's lymphomas, which
comprise about half of the prevalence of the disease in the United States.
Ongoing or completed Phase II studies suggest that Rituxan may also be useful in
combination with chemotherapy in low grade or follicular lymphomas, and as a
single agent, or in combination with various chemotherapies, in the treatment of
other forms of non-Hodgkin's lymphoma. In Phase III clinical trials, Rituxan
given as a single agent to patients with relapsed or refractory, low grade or
follicular, CD20 positive, B-cell non-Hodgkin's lymphoma, demonstrated tumor
shrinkage in 87% of patients. Fifty percent of evaluable patients (76 of 151
patients) achieved partial or complete responses to therapy, i.e., achieved
tumor shrinkage of greater than 50%. The median time to progression (time to
tumor regrowth) in these 76 responders had not been reached at 12.5 months
following initiation of therapy, despite the short duration (22 days) of the
full course of therapy. Rituxan has been well tolerated in clinical studies with
side effects being primarily mild to moderate flu-like symptoms that generally
are limited to the period of infusion. As compared to chemotherapy, Rituxan does
not harm the bone marrow causing the myelosuppression that is a source of much
of chemotherapy-associated morbidity and mortality. Also, Rituxan has been shown
to induce meaningful remissions of disease in poor prognosis patients such as
the elderly, patients failing autologous bone marrow transplants and/or
anthracycline containing therapies, and patients who have become refractory to
chemotherapy.

In 1996, the Company and Genentech completed a Phase III trial of Rituxan
at over 30 clinical sites including leading cancer centers in the United States
and Canada. In this Phase III open label, single arm testing of Rituxan as a
single agent therapeutic, each of the patients participating in the study
received four infusions of the antibody on an outpatient basis during a 22-day
period. Of the 166 patients entered into the study, 161 completed all four
courses of therapy. Of the 166 patients entered into the study, 151 patients
were evaluable for response rate analysis. The 15 patients not considered
evaluable, due to lack of therapy completion or protocol violations are included
in the overall response rate as non-responders. Of 166 patients entered, 80
responded (showed at least 50% reduction in tumor size) to treatment with
Rituxan, for an overall

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response rate of 48%. Ten of these responses were complete responses (6%) and 70
were partial responses (42%). As of the most recent analysis, of the responding
patients, 47% were still in remission at over 12.5 months' median follow-up,
with the longest ongoing duration of response at 22.8 months.

The following table shows the percentage change in tumor size in all 166
patients entered into the Phase III trial of Rituxan in B-cell non-Hodgkin's
lymphoma. Though all patients had progressive disease at the initiation of
treatment, 87% showed evidence of reduction in tumor bulk. Among the responders
(tumor shrinkage of at least 50%), the median tumor shrinkage was 90%.

MAXIMUM PERCENTAGE CHANGE IN TUMOR SIZE AMONG ALL TREATED PATIENTS(1)

LOGO

(1) Tumor shrinkage measured radiographically for the 166 patients
by sum of products of lesion perpendicular diameters. Data
represents the greatest shrinkage achieved by each patient
during the observation period. Subsequent tumor growth may
have occurred and data for three patients are unavailable.

(2) Includes two patients with increase in lesion size greater
than 100%.

Retrospective analysis of patient subgroups in the Phase III Rituxan trial
showed responses in patients with poor prognostic features such as age greater
than 60, extranodal disease, prior relapse from autologous bone marrow
transplant, or relapse or failure of anthracycline containing regimens.

The most common adverse events associated with Rituxan, based on the
Company's clinical trial experience, were infusion-related, consisting mainly of
mild to moderate flu-like symptoms (e.g., fever, chills, rigors) that occurred
in the majority of patients during the first infusion. Other events which
occurred with less frequency included nausea, rashes, fatigue and headaches.
More serious events included hypotension, wheezing, sensation of tongue or
throat swelling and recurrence of cardiac events in patients with a history of
angina or arrhythmia. These symptoms were usually limited in duration to the
period of infusion and

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<PAGE> 33

decreased with subsequent infusions. These adverse events are generally more
mild and of a shorter duration than the adverse events associated with
chemotherapy.

In addition to these findings, the Company observed the disappearance from
the patients' bone marrow of a chromosomal translocation marker (bcl-2)
associated with malignant cells, which was present prior to treatment. The tumor
marker gene reverted to negative in the peripheral blood of over 70% of the
patients who were positive at baseline, and in the bone marrow of over 50% of
patients who were positive at baseline. Researchers have previously reported
clearance of this marker from bone marrow with marrow transplantation regimens
incorporating ex-vivo marrow purging and only rarely with chemotherapy regimens.
However, the clinical significance of bcl-2 conversion has not yet been
determined.

The completion of the Phase III clinical trial supported the submission to
the FDA in February 1997, by the Company and Genentech, of BLAs for Rituxan as a
single agent therapy for the treatment of relapsed or refractory, low grade or
follicular, CD20 positive, B-cell non-Hodgkin's lymphoma. Hoffmann-LaRoche also
submitted an MAA with the EMEA for marketing Rituxan (under the trade name
MabThera) in Europe. On November 26, 1997, IDEC received approval from the FDA
to begin marketing Rituxan in the United States. On November 28, 1997,
Hoffmann-LaRoche received approval to begin marketing MabThera in Switzerland.
Approval to begin marketing in the 15 European Union countries is not
anticipated until mid-1998, at the earliest.

In an effort to identify expanded applications for Rituxan, the Company, in
conjunction with Genentech, has authorized over 35 Rituxan post-marketing trials
to date. Several of these trials will explore the use of Rituxan in a variety of
investigational B-cell non-Hodgkins lymphoma clinical settings including: (i)
combination therapy with widely used chemotherapy regimens for both low grade
and intermediate/high grade disease; (ii) single agent therapy in newly
diagnosed, previously untreated low grade disease; (iii) integration into
Autologous Bone Marrow Transplant regimens both as an in-vivo purging agent
prior to bone marrow harvest and post-transplant as consolidation therapy; and
(iv) treatment of AIDS-related lymphoma. Additionally, clinical trials will be
initiated in other B-cell malignancies and pre-malignant conditions such as CLL,
multiple myeloma and lymphoproliferative disorders associated with solid organ
transplant therapies.

Also, the Company and Genentech have committed to providing drug to a small
group of trials to be undertaken by NCI-funded cooperative study groups. At
least two of these trials will be large Phase III studies designed to explore
the utility of Rituxan in combination with standard chemotherapy regimens. No
assurance can be given that such trials will be successful or that any of them
will lead to a broadening of the usage of Rituxan.

IDEC-Y2B8 and IDEC-In2B8. Due to the sensitivity of B-cell tumors to
radiation, radiation therapy has historically played, and continues to play, an
important role in the management of B-cell lymphomas. Radiation therapy
currently consists of external beam radiation focused on certain areas of the
body with tumor burden. IDEC Pharmaceuticals is developing two antibody products
which are intended to deliver targeted immunotherapy by means of injectable
radiation to target sites expressing the CD20 determinant, such as lymphatic
B-cell tumors, targeted for later stage patients requiring more aggressive
treatment. In clinical testing, IDEC-In2B8 is first used to image the patient's
tumor and to ensure that normal organs are not exposed to undue radiation from
the subsequently administered therapeutic product. The low-energy gamma particle
emitted by IDEC-In2B8 is detectable outside the body, thereby allowing the
physician to determine the localization of the antibody in the tumor. The
companion therapeutic product, IDEC-Y2B8, provides targeted radiation therapy by
emitting a high-energy beta particle that is absorbed by surrounding tissue,
leading to tumor destruction. The Company's objective with these products is to
provide safer, more effective radiation therapy than is possible with external
beam radiation and to provide this radiation therapy in an outpatient setting.

IDEC-Y2B8 is an anti-CD20 murine antibody that is securely bound to the
isotope yttrium-90. This radioisotope is well suited for therapeutic purposes
because of its energy, radius of activity and half-life. It emits only beta
radiation. Other radioisotopes, such as iodine-131, emit both beta and gamma
radiation and at certain therapeutic doses require that the patient be
hospitalized and isolated in a lead-shielded room for

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several days. In contrast, the beta particle emitted by yttrium-90 is absorbed
by tissue immediately adjacent to the antibody. The Company believes that this
short penetrating radiation will permit the use of the product in outpatient
therapy, and has conducted its clinical trials in the outpatient setting.

The Company completed a dose-escalating Phase I clinical trial with
IDEC-Y2B8 in early 1995. Single doses of IDEC-Y2B8 showed clinical activity
comparable to that of intensive, multiple dose, salvage chemotherapy, with
response durations exceeding those of the patients' most recent chemotherapy. In
August 1996, the Company initiated a clinical trial that incorporates both
IDEC-Y2B8 and Rituxan, and results of this trial were reported at the December
1997 meeting of the American Society of Hematology ("ASH"). In this open label,
Phase I/II clinical trial, patients with advanced, relapsed B-cell non-Hodgkin's
lymphoma received pretreatment with Rituxan to maximize tumor localization and
efficacy of subsequently administered IDEC-Y2B8. Patients received 250mg/m(2) of
Rituxan plus an imaging dose of IDEC-In2B8 on day one. During the following
week, patient tumors were imaged using the low-energy gamma radiation emitted by
the indium isotope. On day eight, patients received a second infusion of Rituxan
at 250mg/m(2) followed by a therapeutic dose of IDEC-Y2B8 at 0.2, 0.3 or 0.4
mCi/kg of body weight. Across all dose groups, an 82% response rate was seen in
the subpopulation of B-cell non-Hodgkin's lymphoma (with a total of 31 patients
having been evaluated). At the dose group of 0.4 mCi/kg, a 100% overall response
rate was seen (seven of seven patients) in this patient population.

The Company has initiated a Phase III trial of IDEC-Y2B8 for the proposed
treatment of B-cell non-Hodgkin's lymphoma. Accrual for this trial should be
completed in approximately one year. For this trial, 0.4 mCi/kg has been
selected as the standard dose, with patients having low platelet counts being
eligible for treatment at the lower dose of 0.3 mCi/kg.

The Company expects that Rituxan and IDEC-Y2B8 will provide complementary
products for the management of non-Hodgkin's lymphomas. Because most lymphomas
are treated today in community-based group practices, Rituxan fits nicely into
the community practice, as no special equipment or extensive training is
required for its administration or for management of treatment related side
effects. Rituxan has shown activity even in patients refractory to chemotherapy
and is indicated for this use, so that it may provide a viable option for the
community-based oncologist prior to referral of the patient to the major medical
center for treatment with more aggressive therapies, potentially including
IDEC-Y2B8. By contrast, all radioimmunotherapies will be administered by the
nuclear medicine specialist or radiation oncologist at the major medical center
that is equipped for the handling, administration and disposal of radioisotopes.
Also, the nuclear medicine department, but not the community-based practice, has
the specialized equipment and governmental licenses that are required for use of
radioisotopes. Thus the Company believes that referral patterns will develop for
treatment of lymphoma patients with radioimmunotherapies at major medical
centers after the community-based oncologist has exhausted all other options,
such as Rituxan or chemotherapy, for the management of his or her patients. This
trend will be further reinforced by the observation made by the Company, and by
others working in the field, of the substantial clinical activity of
radioimmunotherapies in patients with late-stage disease that has become
refractory to chemotherapies. Thus, IDEC Pharmaceuticals is committed to the
development and commercialization of Rituxan and the investigational agent
IDEC-Y2B8 as complementary products which might be used throughout the course of
a patient's disease providing alternatives, for both the patient and the
healthcare professional, to conventional chemotherapies.

9-Aminocamptothecin. In July 1997, IDEC Pharmaceuticals completed its
acquisition of worldwide rights to 9-AC from Pharmacia & Upjohn. This drug was
acquired as part of a consent decree issued by the Federal Trade Commission
("FTC") regarding the merger of Pharmacia AB with The Upjohn Company. IDEC
Pharmaceuticals now holds exclusive rights to all licenses and technology
related to 9-AC and is proceeding with clinical development of the compound. In
preclinical and Phase I/II clinical studies conducted by Pharmacia & Upjohn and
the NCI, 9-AC has shown broad-spectrum activity against a variety of solid
tumors. A semi-synthetic analogue of the plant-derived molecule camptothecin,
9-AC belongs to a class of drugs known as camptothecins that interferes with DNA
replication by inhibiting a critical nuclear enzyme, topoisomerase I. During
1996, two compounds from the camptothecin class were approved for marketing by
the FDA: Hycamptin(R) (SmithKline Beecham) for the treatment of ovarian cancer
and Camptosar(R) (Pharmacia & Upjohn) for the treatment of colorectal cancer. In
October 1997, the Company

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announced that it had begun treating patients as part of a Phase I/II clinical
trial of 9-AC. The trial, is aimed at verifying the maximum tolerated dose of
9-AC, determined by other investigators in earlier trials, and at seeking an
initial indication to pursue for marketing approval. The investigational study
population includes patients with any one of eight solid tumor types: non-small
cell lung, colorectal, pancreatic, gastric, bladder, prostate, head and neck, or
kidney. The initial protocol of the Phase I/II study, being managed at the
University of Alabama, is an escalating dose safety study of 9-AC in nine
patients. Once the maximum tolerated dose is confirmed, the Company expects that
patients, up to a total of 14 individuals in each of the targeted tumor types,
will be enrolled in Phase IIA of the study. The Company intends to involve
additional centers in the Phase II portion of the trial. If the investigators
see at least one response in any tumor type, additional patients with that
cancer will be studied in Phase IIB of the trial to determine an estimate of the
response rate for that disease. Once the investigators identify a meaningful
response rate for one or more tumor types, the Company intends to choose one of
those indications to take into a registration or pivotal study.

AUTOIMMUNE AND INFLAMMATORY PRODUCTS

IDEC Pharmaceuticals is developing a new class of antibodies, termed
PRIMATIZED antibodies, that are of part human, part macaque monkey, origin.
These antibodies are structurally similar to, and potentially indistinguishable
by a patient's immune system from, human antibodies. PRIMATIZED antibodies may
provide therapeutic intervention for diseases or conditions not amenable to
chronic treatment with mouse-derived antibodies. The Company's objective with
its PRIMATIZED antibodies is to provide therapies that can be used to control
autoimmune diseases characterized by overactive immune functions. The Company
has entered into research and development collaborations with SmithKline
Beecham, Mitsubishi, Seikagaku and Eisai, all of which utilize the Company's
PRIMATIZED technology and which target distinct, cell surface determinants or
soluble mediators. See "-- Strategic Alliances."

PRIMATIZED IDEC-151 and IDEC-CE9.1. In June 1997, the Company and
SmithKline Beecham announced that they had suspended further enrollment and
treatment in the Phase III and supportive clinical trials of IDEC-CE9.1
(designated SB-210396 by SmithKline Beecham for its clinical development) for
the treatment of rheumatoid arthritis. This decision was based on observations
of lowered CD4 cell counts in a higher number of treated patients in the Phase
III study compared to the rate observed in the earlier Phase II trial. While
there have been no reports of side effects related to lower CD4 counts in the
Phase III trial, the companies decided to place a hold on clinical trials with
IDEC-CE9.1 pending a thorough review and analysis of the data. The Company
expects to receive the analysis of this information in February 1998.

A blinded assessment of CD4 cell counts in the Phase III trial of
IDEC-CE9.1 showed that 35 out of 103 patients completing the first month of
treatment had reduced CD4 cell counts, compared to 10 of 136 measured at the
same point in the Phase II trial. Five of these ten patients in Phase II had a
reduction of CD4 counts for three months or longer. The duration of CD4 count
reduction in the Phase III trial will be assessed as part of the ongoing
follow-up. No efficacy assessment has been made to date in the Phase III trial,
but an evaluation will be made for patients who have completed the initial part
of the trial. The earlier Phase II study demonstrated significant clinical
improvement in the signs and symptoms of rheumatoid arthritis with IDEC-CE9.1
treatment. For example, according the American College of Rheumatology ACR-20
composite endpoint, 69%, 51% and 42% response rates were seen in the 140mg, 80mg
and 40mg dose groups, respectively, versus 19% in the placebo group in this
double-blinded, Phase II study.

The reason for the observed discrepancy in frequency of CD4 depletion
between the Phase III trial and the earlier Phase II experience is uncertain.
Potential sources of this variation, including dose and schedule changes,
manufacturing changes and patient variables, will be investigated as part of a
comprehensive review of preclinical and clinical data. This assessment will
guide decisions regarding the further development of IDEC-CE9.1.

In addition to the IDEC-CE9.1 antibody, a second generation anti-CD4
antibody, IDEC-151 (designated SB-217969 by SmithKline Beecham for its clinical
development), is currently in a Phase I/II trial for rheumatoid arthritis. This
antibody is similar in its CD4 binding properties to IDEC-CE9.1, but is

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engineered with a human gamma 4 constant region with reduced cell depletion
potential. On December 2, 1997, the Company and SmithKline Beecham announced
results of the Phase I portion of this trial for the treatment of rheumatoid
arthritis. The findings in this single dose, dose-escalating,
placebo-controlled, double-blinded portion of the study in 32 patients with
moderate to severe rheumatoid arthritis, showed no depletion in CD4 cells, no
infusion-related adverse events, and longer coating action when IDEC-151 was
administered at high doses compared to the first generation PRIMATIZED antibody,
IDEC-CE9.1. Longer cell-coating action may be important for enhanced clinical
activity and may enable less frequent dosing as compared to IDEC-CE9.1. During
the first half of 1998, the Company and SmithKline Beecham expect to determine
the development courses to take with the two antibodies that they have in joint
development. One possible outcome is the decision to abandon IDEC-CE9.1 in
preference for IDEC-151, pending a successful outcome with the latter antibody
in the ongoing multi-dose portion of the Phase I/II trial.

Humanized Anti-gp39 (IDEC-131) and PRIMATIZED Anti-gp39. In December 1995,
the Company entered into a research and development collaborative agreement with
Eisai. The collaboration focuses on developing humanized and PRIMATIZED
antibodies against the gp39 antigen. This antigen, also referred to as the CD40
ligand, is an essential immune system trigger for B-cell activation and antibody
production. Potential target indications include transplantation and
antibody-mediated autoimmune diseases such as idiopathic thrombocytopenic
purpura ("ITP") and SLE. The development of the Company's humanized anti-gp39
monoclonal antibody ("IDEC-131") is based on technology that the Company
licensed from Dartmouth College, where researchers have shown that the binding
of gp39 to its CD40 receptor on B cells is essential for proper immune system
function. These researchers generated anti-gp39 antibodies that blocked this
T-cell and B-cell interaction and halted disease progression in a variety of
animal models of disease characterized by abnormal or unwanted immune response.
Moreover, when researchers ended the animals' anti-gp39 treatments, the animals'
antibody-producing capacity returned to normal levels, but their disease
remained suppressed. Treatment with the anti-gp39 antibodies appeared to have
reset the animals' immune systems and restored a normal immune response. Under
the collaborative agreement, the Company and Eisai have agreed to develop a
humanized anti-gp39 antibody and launch additional efforts to develop a second
generation, PRIMATIZED anti-gp39 antibody. This effort has resulted in the
identification of the humanized anti-gp39 antibody lead candidate, IDEC-131,
which underwent preclinical testing, process development and manufacturing of
clinical trial material in early 1997. The Company filed an IND for IDEC-131 in
November 1997 and began a Phase I clinical study in SLE in February 1998.

PRIMATIZED Anti-B7. In November 1993, the Company entered into a research
and development collaboration with Mitsubishi that focuses on the development of
PRIMATIZED antibodies directed at a B7 determinant. This B7 determinant appears
on the surface of antigen-presenting cells and is involved in the interaction of
these cells with T cells in triggering a cascade of immune system responses.
Antibodies directed at B7 determinants may block this cascade and, therefore,
may be useful in preventing unwanted immune responses in certain inflammatory
and chronic autoimmune conditions such as psoriasis, arthritis and MS.
Mitsubishi has actively shared in the development process, generating animal
models and participating in research with the Company. This effort has resulted
in the identification of a PRIMATIZED antibody lead candidate which is
undergoing preclinical testing, process development and manufacturing of
clinical material.

PRIMATIZED Anti-CD23. In December 1994, the Company entered into a
collaboration with Seikagaku aimed at the development of PRIMATIZED anti-CD23
antibodies for the potential treatment of allergic rhinitis, asthma and other
allergic conditions. Antibodies against the CD23 receptor on certain white blood
cells inhibit the production of immune system molecules called immunoglobulin
class E, or IgE, which are known to trigger allergic conditions. At the same
time, anti-CD23 antibodies do not affect the production of the immunoglobulins
(the patient's own antibodies) responsible for granting protective immunity to
infectious agents. Thus, PRIMATIZED anti-CD23 antibodies may provide a unique
new approach to treating chronic illnesses such as allergic rhinitis and asthma.
This effort has resulted in the identification of a PRIMATIZED antibody lead
candidate which is expected to undergo preclinical testing, process development
and manufacturing of clinical material during 1998.

Humanized and PRIMATIZED Anti-MIF. MIF (macrophage migration inhibitory
factor) is the body's natural counter-regulatory cytokine which serves to
override the anti-inflammatory activities of natural and

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administered steroids. Inhibition of MIF may represent a novel approach to the
management of a variety of acute and chronic inflammatory diseases, including
steroid-resistant rheumatoid arthritis and asthma. In September 1997, IDEC
Pharmaceuticals licensed from CNI, a privately-held biopharmaceutical company,
development rights to CNI's anti-MIF antibody technology. Under the terms of the
licensing and development agreement, the Company became the exclusive licensee
of CNI's rights to the anti-MIF antibody technology for therapeutic and
diagnostic applications. In return for these rights, the Company made a $3.0
million preferred equity investment in CNI, which will also receive milestone
payments and royalties on the sales by the Company of approved products
resulting from the collaboration.

STRATEGIC ALLIANCES

The Company has entered into one or more strategic partnering arrangements
for each of its principal product development programs. Through these strategic
partners, the Company is funding a significant portion of its product
development costs and is capitalizing on the production, development,
regulatory, marketing and sales capabilities of its partners. Unless otherwise
indicated, the amounts shown below as potential payments include license fees,
research and development fees and, with respect to Genentech, SmithKline Beecham
and Zenyaku, equity investments, but do not include potential royalties. The
Company's entitlement to such payments depends on achieving milestones related
to development, clinical trials results and regulatory approvals and other
factors. These arrangements include:

Genentech, Inc. In March 1995, the Company and Genentech entered into a
collaborative agreement for the clinical development and commercialization of
the Company's anti-CD20 monoclonal antibody, Rituxan, for the treatment of
B-cell non-Hodgkin's lymphomas. Concurrent with the collaborative agreement, the
Company and Genentech also entered into an expression technology license
agreement for a proprietary gene expression technology developed by the Company
and a preferred stock purchase agreement providing for certain equity
investments in the Company by Genentech. Under the terms of these agreements,
the Company may receive payments totaling $58.5 million, subject to the
attainment of certain milestones, of which $48.5 million has been recognized
through December 31, 1997. In addition, the Company and Genentech are
co-promoting Rituxan in the United States. Genentech retained commercialization
rights throughout the rest of the world, except in Japan. Genentech has granted
Hoffmann-LaRoche marketing rights outside of the United States, and
Hoffmann-LaRoche has elected to market Rituximab under the trade name Mabthera.
The Company and Hoffmann-LaRoche are currently discussing an arrangement for
commercialization of Rituxan in Canada, but no assurance can be given that an
arrangement will be found which will be satisfactory to the Company,
Hoffmann-LaRoche and Genentech, which previously held co-promotion rights to
Canada along with IDEC Pharmaceuticals. The Company will receive royalties on
sales outside the United States and Canada. The collaborative agreement between
the Company and Genentech provides two independent mechanisms by which either
party may purchase or sell its rights in the co-promotion territory from/to the
other party. Upon the occurrence of certain events that constitute a change of
control of the Company, Genentech may elect to present an offer to the Company
to purchase the Company's co-promotion rights. The Company must then accept
Genentech's offer or purchase Genentech's co-promotion rights for an amount
scaled (using the profit sharing ratio between the parties) to Genentech's
offer. Under a second mechanism, after a specified period of commercial sales
and (i) upon a certain number of years of declining co-promotion profits or (ii)
if Genentech files for U.S. regulatory approval on a competitive product during
a limited period of time, either party may offer to purchase the other party's
co-promotion rights. The offeree may either accept the offer price or purchase
the offeror's co-promotion rights at the offer price scaled to the offeror's
share of co-promotion profits. See "Description of Capital Stock."

SmithKline Beecham, p.1.c. In October 1992, the Company and SmithKline
Beecham entered into an exclusive worldwide collaborative research and license
agreement limited to the development and commercialization of therapeutic
products based on the Company's PRIMATIZED anti-CD4 antibodies. Under the terms
of this agreement, the Company may receive payments in excess of $60.0 million,
subject to the attainment of certain milestones, of which $32.6 million has been
recognized through December 31, 1997. The Company will receive funding for
anti-CD4 related research and development programs, as well as royalties and a
share of co-promotion profits in the United States and Canada on sales of
products which may

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be commercialized as a result of the collaboration. At any time, SmithKline
Beecham may terminate this agreement by giving the Company 30 days' written
notice based on a reasonable determination that the products do not justify
continued development or marketing. In connection with the collaboration,
SmithKline Beecham purchased shares of the Company's Common Stock and warrants
exercisable into Common Stock.

Mitsubishi Chemical Corporation. In November 1993, the Company entered into
a three-year collaborative agreement with Mitsubishi for the development of a
PRIMATIZED anti-B7 antibody. Under the terms of the agreement, the Company may
receive payments totaling $12.2 million to fund research of the PRIMATIZED
anti-B7 antibody, subject to the attainment of certain milestones, of which $7.2
million has been recognized through December 31, 1997. Under the agreement, the
Company has granted Mitsubishi an exclusive license in Asia to make, use and
sell PRIMATIZED anti-B7 antibody products. The Company will receive royalties on
sales of the developed products by Mitsubishi. At any time, Mitsubishi may
terminate this agreement by giving the Company 30 days' written notice based on
a reasonable determination that the products do not justify continued
development or marketing or based on failure to reach milestones.

Seikagaku Corporation. In December 1994, the Company and Seikagaku entered
into a collaborative development agreement and a license agreement aimed at the
development and commercialization of therapeutic products based on the Company's
PRIMATIZED anti-CD23 antibodies. Under the terms of these agreements, Seikagaku
may provide up to $26.0 million in milestone payments and support for research
and development, subject to the attainment of certain milestones, of which $14.5
million has been recognized through December 31, 1997. Under the agreement,
Seikagaku has received exclusive rights in Europe and Asia to all products
emerging from the collaboration. The Company will receive royalties on eventual
product sales by Seikagaku. At any time, Seikagaku may terminate this agreement
by giving the Company 60 days' written notice based on a reasonable
determination that the products do not justify continued development or
marketing.

Eisai Co., Ltd. In December 1995, the Company and Eisai entered into a
collaborative development agreement and a license agreement aimed at the
development and commercialization of humanized and PRIMATIZED anti-gp39
antibodies. Under the terms of these agreements, Eisai may provide up to $37.5
million in milestone payments and support for research and development, subject
to the attainment of certain milestones and satisfaction of other criteria to be
agreed upon between the parties, of which $15.6 million has been recognized
through December 31, 1997. Eisai will receive exclusive rights in Asia and
Europe to develop and market resulting products emerging from the collaboration,
with the Company receiving royalties on eventual product sales by Eisai. At any
time, Eisai may terminate this agreement by giving the Company 60 days' written
notice based on a reasonable determination that the products do not justify
continued development or marketing.

Chugai Pharmaceutical Co., Ltd. In March 1996, the Company and Chugai
entered into a worldwide license agreement (co-exclusive with IDEC
Pharmaceuticals, Genentech and up to two additional companies) for the Company's
proprietary vector technology for high expression of recombinant proteins in
mammalian cells. As part of the agreement, Chugai paid an up-front licensing fee
of $4.5 million to the Company and will pay royalties on sales of Chugai
products manufactured using the technology.

Boehringer Ingleheim GmbH. In December 1996, the Company and Boehringer
Ingleheim GmbH ("BI") entered into a worldwide license agreement (co-exclusive
with IDEC Pharmaceuticals, Genentech and up to two additional companies) for the
Company's proprietary gene expression technology (its "vector technology") for
high expression of recombinant proteins in mammalian cells. As part of the
agreement, BI paid an up-front licensing fee of $5.1 million to the Company and
will pay royalties on sales of BI products manufactured using the technology.

Kirin Brewery Co., Ltd., Pharmaceutical Division. In December 1997, the
Company and Kirin Brewery Co., Ltd., Pharmaceutical Division ("Kirin") entered
into a worldwide license agreement (co-exclusive with IDEC Pharmaceuticals,
Genentech and up to two additional companies) for the Company's proprietary
vector technology for high expression of recombinant proteins in mammalian
cells. As part of the agreement, Kirin paid an up-front licensing fee of $6.3
million to the Company, which will be recognized in the first quarter of 1998,
and will pay royalties to the Company on sales of Kirin products manufactured
using the technology.

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MANUFACTURING

From its inception, the Company has focused on establishing and maintaining
a leadership position in cell culture techniques for antibody manufacturing.
Cell culture provides a method for manufacturing of clinical and commercial
grade protein products by reproducible techniques at various scales, up to many
kilograms of antibody. The Company's manufacturing facility is based on the
suspension culture of mammalian cells in stainless steel vessels. Suspension
culture fermentation provides greater flexibility and more rapid production of
the large amounts of antibodies required for pivotal trials than the bench-scale
systems that were previously utilized by the Company. During 1995, the Company
doubled the cell culture manufacturing capacity of its facility with the
installation of a second 2,750-liter production vessel that is supported by
existing upstream and downstream equipment. The Company's manufacturing facility
has been approved by the FDA only for the commercial manufacture of Rituxan and
may not be used for the commercial manufacture of other products. Additionally,
the Company is contractually required to manufacture Rituxan to capacity through
the end of 1999, and may not produce other products except in a separate
small-scale manufacturing area dedicated to the manufacture of clinical
materials (see "CMA" below). The Company estimates that, at full capacity, it
can produce within its facility enough Rituxan to treat approximately 25,000
patients per year at the approved dosage regime. See "-- Government Regulation."

During 1997, the Company completed construction of a new clinical cell
culture manufacturing area ("CMA") within the Company's Torreyana facility. The
CMA should allow for the manufacture under cGMP regulations of proteins by the
Company to meet its current projected Phase I and Phase II requirements, but the
CMA will not allow for the clinical manufacture of the drug 9-AC.

Because the Company's capacity is committed to the manufacture of Rituxan
for two years, it will not have the cell culture capacity to manufacture
commercial material for the Company's IDEC-Y2B8 and In2B8 products during such
period. The Company is currently accepting proposals for a qualified commercial
contractor to meet the long term manufacturing demands for IDEC-Y2B8 and In2B8.
In addition, as the Company does not have expertise or facilities for small
molecule chemical manufacturing, the Company will need to establish a long term
manufacturing arrangement for 9-AC with an appropriate contract manufacturer.
IDEC's 9-AC clinical materials requirements will be met over the next two years
by Pharmacia & Upjohn, as part of the product in-license agreement.
Additionally, as the Company does not have fill/finish expertise, the Company
will be dependent on outside contractors to meet IDEC's current and future
requirements for fill/finish. See "Risk Factors -- Limited Manufacturing
Experience."

During 1998, the Company plans to manufacture Rituxan at its manufacturing
facility in San Diego, California. The Company anticipates that its facility in
San Diego should provide sufficient production capacity to meet clinical and
early commercial requirements of Rituxan. The Company is dependent upon
Genentech to fill/finish and meet long-term manufacturing demands for Rituxan
and SmithKline Beecham to fulfill all of the manufacturing requirements for
IDEC-CE9.1 and/or IDEC-151. Genentech is currently constructing additional
manufacturing capacity in part to satisfy long-term demands for Rituxan and
SmithKline Beecham has constructed a larger manufacturing plant for IDEC-CE9.1
and/or IDEC-151. The Company is considering the addition of another
manufacturing facility to meet its long-term requirements for additional
products under development.

The Company has made its vector technology platform available for licensing
to a small number of other biopharmaceutical and pharmaceutical companies. In
March 1995, Genentech, one of the premier companies in recombinant DNA-based
production, became the first to license the Company's gene expression technology
for its own product development efforts. This technology has also been licensed
to Chugai, BI and Kirin.

SALES AND MARKETING

During 1998, the Company will depend on the successful marketing and sales
of Rituxan for much of its anticipated revenue. Rituxan will be marketed and
sold in the United States pursuant to a co-promotion agreement with Genentech,
which currently has a sales and marketing staff of approximately 50
professionals that is largely dedicated to the commercialization of Rituxan. To
fulfill its duties under the co-promotion agreement, the Company has recently
created a marketing staff and a sales organization of 32 professionals

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with experience primarily in the oncology therapeutic category, who will be
dedicated exclusively to the commercialization of Rituxan. The Company expects
to add two more employees to this staff in 1998. The Company will rely heavily
on Genentech to supply related marketing support services including customer
service, order entry, shipping and billing, customer reimbursement assistance,
managed-care sales support, medical information, and sales training. There can
be no assurance that the Company's sales and marketing staff will successfully
transition the Company into long-term profitability. Furthermore, there can be
no assurance that Genentech will successfully perform its role in the
co-promotion relationship.

Commercialization of the Company's products is expensive and
time-consuming. The Company has adopted a strategy of pursuing collaborative
agreements with strategic partners that provide for co-promotion of certain of
the Company's products. To the extent that the Company elects to participate in
co-promotion efforts in the United States or Canada, and in those instances
where the Company retains exclusive marketing rights in specified territories,
the Company will need to maintain and expand its sales and marketing effort in
order to establish a successful direct sales capability in the targeted markets.
The Company will also need to build marketing support services including
customer service, order entry, shipping and billing, customer reimbursement
assistance, managed-care sales support, medical information and sales training.
There can be no assurance that the Company will be able to establish a
successful direct sales and marketing capability in any or all targeted markets
or that it will be successful in gaining market acceptance for its products. To
the extent that the Company has entered or in the future enters into
co-promotion or other licensing arrangements, any revenues received by the
Company will be dependent on the efforts of third parties and there can be no
assurance that such efforts will be successful. Failure to establish a sales
capability either in the United States or outside the United States may have a
material adverse effect on the Company. See "Business -- Sales and Marketing."

PATENTS AND PROPRIETARY TECHNOLOGY

The biopharmaceutical field is characterized by a large number of patent
filings. A substantial number of patents have already been issued to other
biotechnology and biopharmaceutical companies. Particularly in the monoclonal
antibody field, competitors may have filed applications for or have been issued
patents and may obtain additional patents and proprietary rights relating to
products or processes competitive with or similar to those of the Company. To
date, no consistent policy has emerged regarding the breadth of claims allowed
in biopharmaceutical patents. Moreover, United States and foreign country patent
laws are distinct and the interpretations thereunder unique to each country.
Thus, patentability, validity and infringement issues for the same technology or
inventions may be resolved differently in different jurisdictions. There can be
no assurance that patents do not exist in the United States or in foreign
countries or that patents will not be issued that would have an adverse effect
on the Company's ability to market its products. Accordingly, the Company
expects that commercializing monoclonal antibody-based products may require
licensing and/or cross-licensing of patents with other companies in the field.
There can be no assurance that the licenses, which might be required for the
Company's processes or products, would be available on commercially acceptable
terms, if at all. The ability to license any such patents and the likelihood of
successfully contesting the scope or validity of such patents are uncertain and
the costs associated therewith may be significant. If the Company is required to
acquire rights to valid and enforceable patents but cannot do so at a reasonable
cost, the Company's ability to manufacture or market its products would be
materially adversely affected.

IDEC Pharmaceuticals is the assignee of seven issued and 14 allowed U.S.
patents, 16 U.S. patent applications and numerous corresponding foreign patent
applications. Certain other patents and/or applications owned by third parties
have been exclusively licensed, as in the case of anti-gp39 core technology
licensed from Dartmouth College, or non-exclusively licensed by IDEC
Pharmaceuticals. The Company has filed trademark applications in the United
States, Canada and in certain international markets for the

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trademarks "PRIMATIZED," "PROVAX," "Rituxan" and "IDEC Pharmaceuticals." "IDEC
Pharmaceuticals" and "PRIMATIZED" have been registered as trademarks in the
United States.

The Company has allowed and pending U.S. patent applications and pending
foreign counterparts broadly directed to its pan-B antibody technology,
including Rituxan, and the radioimmunoconjugates, IDEC-Y2B8 and IDEC-In2B8. The
Company's radioimmunoconjugate products include a chelating agent covered by a
U.S. patent that is non-exclusively sublicensed to the Company. The Company has
been granted by the European Patent Office a patent covering Rituxan. Genentech,
IDEC Pharmaceuticals' collaborative partner for Rituxan, has secured an
exclusive license to a U.S. patent and counterpart foreign patent applications
assigned to Xoma Corporation ("Xoma"), that relate to chimeric antibodies
against the CD20 antigen. Genentech has granted IDEC Pharmaceuticals a
non-exclusive sublicense to make, have made, use and sell certain products,
including Rituxan, under such patents and patent applications. Genentech and the
Company will share any royalties due to Xoma in the Genentech/IDEC
Pharmaceuticals co-promotion territory.

The Company has filed for worldwide patent protection on its PRIMATIZED
antibody technology. In August 1997, the Company received U.S. Patent No.
5,658,570 claiming the Company's PRIMATIZED antibodies. Three additional U.S.
patents claiming the PRIMATIZED antibody technology were allowed in 1997. These
patents and applications generically and specifically cover the Company's
PRIMATIZED antibody technology.

PROVAX, the Company's antigen formulation, is the subject matter of two
issued U.S. patents, two allowed U.S. patents, one pending U.S. application and
pending foreign counterparts. In addition, U.S. and foreign patent applications
have been filed on aspects of the Company's proprietary high-yield gene
expression technology, including the Company's homologous recombination system.
The Company has been granted U.S. Patent No. 5,648,267 and has received a notice
of allowance on a U.S. patent claiming the high-yield gene expression
technology. In early 1998, the Company also received a Notice of Allowance for a
U.S. patent directed to its homologous recombination technology.

In late 1997, the Company received Notices of Allowance for six U.S.
patents. The first is directed to a patent claiming the Company's anti-gp39
patent, IDEC-131, and the remaining five broadly claim the Company's anti-RSV
antibody technology. Foreign counterparts of these allowed patents are pending.

The Company is aware of several third-party patents and patent applications
that, if successfully asserted against the Company, would affect the Company's
ability to make, use, offer to sell, sell and import its products. These
third-party patents and, patent applications include:

(i) U.S. patent applications and foreign counterparts filed by
Bristol-Myers Company that disclose antibodies to a B7 antigen;

(ii) a U.S. patent assigned to Columbia University, which the Company
believes has been exclusively licensed to Biogen, related to monoclonal
antibodies to the 5C8 antigen found on T cells. The Company believes the
5C8 antigen and gp39, the target for the Company's anti-gp39 antibodies and
its collaboration with Eisai, may be the same protein expressed on the
surface of T cells;

(iii) a number of issued patents that relate to various aspects of
radioimmunotherapy of cancer and to methods of treating patients with
anti-CD4 antibodies; and

(iv) three U.S. patents, assigned to Burroughs Wellcome, relating to
therapeutic uses of CHO glycosylated antibodies.

The owners, or licensees of the owners, of these patents may assert that
one or more of the Company's products infringe one or more claims of such
patents. Specifically, if legal action is commenced against the Company to
enforce any of these patents and the plaintiff in such action prevails, the
Company could be prevented from practicing the subject matter claimed in such
patents. In such event or under other appropriate circumstances, the Company may
attempt to obtain licenses to such patents. However, no assurance can be given
that any owner would license the patents to the Company, at all or on terms that
would permit commercialization of the Company's products using such technology.
An inability to commercialize such

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<PAGE> 42

products would have a material adverse effect on the Company's business, results
of operations and financial condition.

If the Company is required to enforce any of its patents, such enforcement
may require the use of substantial financial and human resources of the Company.
The Company may also have to participate in interference proceedings if declared
by the PTO to determine priority of invention, which typically take years to
resolve and could also result in substantial costs to the Company. Moreover,
should the Company need to defend against a patent lawsuit circumvent existing
patents, substantial delays and expense in product redesign and development or
significant legal expense and uncertainty in asserting non-infringement,
invalidity and/or unenforceability of any patent may also result. The Company
also relies upon unpatented trade secrets, and no assurance can be given that
others will not independently develop substantially equivalent proprietary
information and techniques or otherwise gain access to the Company's trade
secrets or disclose such technology, or that the Company can meaningfully
protect such rights.

IDEC Pharmaceuticals requires its employees, consultants, outside
scientific collaborators and sponsored researchers and other advisers to execute
confidentiality agreements upon the commencement of employment or consulting
relationships with the Company. These agreements provide that all confidential
information developed or made known to the individual during the course of the
individual's relationship with IDEC Pharmaceuticals is to be kept confidential
and not disclosed to third parties except in specific circumstances. In the case
of employees of the Company, the agreement provides that all inventions
conceived by such employees shall be the exclusive property of the Company.
There can be no assurance, however, that these agreements will provide
meaningful protection or adequate remedies for the Company's trade secrets in
the event of unauthorized use or disclosure of such information.

COMPETITION

The development of therapeutic agents for human disease is intensely
competitive. Many different approaches are being developed or have already been
adopted into routine use for the management of diseases targeted by the Company.
Competitive approaches to the Company's products include radioimmunotherapies
and antibody-drug and antibody-toxin conjugates for cancers, and
chemotherapeutic agents and various immunologically based agents for cancers and
autoimmune disorders. Ultimately, the Company believes that its products will be
competitive or complementary to existing products and other products still in
development. In some cases, the Company's products may be used along with other
agents in "combination therapies."

Many of the Company's existing or potential competitors have substantially
greater financial, technical and human resources than the Company and may be
better equipped to develop, manufacture and market products. In addition, many
of these companies have extensive experience in preclinical testing and human
clinical trials. These companies may develop and introduce products and
processes competitive with or superior to those of the Company. The Company is
aware that certain other companies are in the process of clinical testing of
potentially competitive biotechnology-based products. If approved for the same
indications for which the Company is developing products, such products may make
it more difficult for the Company to obtain approval of its own products or
reduce the potential market shares for the Company's products.

The Company's competition will be determined in part by the potential
indications for which the Company's antibodies are developed and ultimately
approved by regulatory authorities. For certain of the Company's potential
products, an important factor in competition may be the timing of market
introduction versus that of competitive products. Accordingly, the relative
speed with which the Company develops its products, completes the required
approval processes and generates and markets commercial product quantities are
expected to be important competitive factors. The Company expects that
competition among products approved for sale will be based, among other factors,
on product activity, safety, reliability, availability, price, patent position
and new usage and purchasing patterns established by managed care and other
group purchasing organizations.

The Company's competitive position also depends upon its ability to attract
and retain qualified personnel, obtain patent protection or otherwise develop
proprietary products or processes, secure sufficient capital resources to
complete product development and regulatory processes, to build a marketing and
sales

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<PAGE> 43

organization, and to build or obtain large-scale manufacturing facilities, if
required, beyond its facility in San Diego.

GOVERNMENT REGULATION

The testing, manufacturing, labeling, advertising, promotion, export and
marketing, among other things, of the Company's product and proposed products
are subject to extensive regulation by governmental authorities in the United
States and other countries. In the United States, pharmaceutical products are
regulated by the FDA under the Federal Food, Drug, and Cosmetic Act and other
laws, including, in the case of biologics, the Public Health Service Act. At the
present time, with the exception of 9-AC, the Company believes that its products
will be regulated by the FDA as biologics. Biologics require the submission of a
BLA and approval by the FDA prior to being marketed in the United States. 9-AC,
which the Company believes will be regulated by the FDA as a drug, will require
the submission of an NDA and approval by the FDA prior to being marketed in the
United States. The regulatory approval process for an NDA is similar to the
approval process for a BLA. Manufacturers of biologics and drugs may also be
subject to state regulation.

Preclinical tests include laboratory evaluation of the product, as well as
animal studies to assess the potential safety and efficacy of the product. The
results of the preclinical tests, together with manufacturing information and
analytical data, are submitted to the FDA as part of an IND, which must become
effective before human clinical trials may be commenced. The IND will
automatically become effective 30 days after receipt by the FDA, unless the FDA
before that time raises concerns or questions about the conduct of the trials as
outlined in the IND. In such a case, the IND sponsor and the FDA must resolve
any outstanding concerns before clinical trials can proceed. There can be no
assurance that submission of an IND will result in FDA authorization to commence
clinical trials.

Clinical trials involve the administration of the investigational product
to healthy volunteers or patients under the supervision of qualified principal
investigators. Further, each clinical study must be reviewed and approved by an
independent Institutional Review Board.

Clinical trials typically are conducted in three sequential phases, but the
phases may overlap. In Phase I, the initial introduction of the drug into human
subjects, the drug is usually tested for safety (adverse effects), dosage
tolerance, absorption, metabolism, distribution, excretion and pharmacodynamics.
Phase II usually involves studies in a limited patient population to (i)
evaluate preliminarily the efficacy of the drug for specific, targeted
indications, (ii) determine dosage tolerance and optimal dosage and (iii)
identify possible adverse effects and safety risks. Phase III trials generally
further evaluate clinical efficacy and test further for safety within an
expanded patient population.

In the case of products for severe or life-threatening diseases, the
initial human testing is sometimes done in patients rather than in healthy
volunteers. Since these patients are already afflicted with the target disease,
it is possible that such studies may provide evidence of efficacy traditionally
obtained in Phase II trials. These trials are frequently referred to as "Phase
I/II" trials. There can be no assurance that Phase I, Phase II or Phase III
testing will be completed successfully within any specific time period, if at
all, with respect to any of the Company's product candidates. Furthermore, the
FDA may suspend clinical trials at any time on various grounds, including a
finding that the subjects or patients are being exposed to an unacceptable
health risk.

The results of the preclinical studies and clinical studies, together with
detailed information on the manufacture and composition of the product, are
submitted to the FDA in the form of a or BLA or NDA

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<PAGE> 44

requesting approval to market the product. Before approving a BLA or NDA, the
FDA will inspect the facilities at which the product is manufactured, and will
not approve the product unless cGMP compliance is satisfactory. The FDA may deny
a BLA or NDA if applicable regulatory criteria are not satisfied, require
additional testing or information, and/or require postmarketing testing and
surveillance to monitor the safety or efficacy of a product. There can be no
assurance that FDA approval of any BLA or NDA submitted by the Company will be
granted on a timely basis or at all. Also, if regulatory approval of a product
is granted, such approval may entail limitations on the indicated uses for which
it may be marketed.

As a general matter, data regarding, for example, partial tumor shrinkage,
can be developed in less time than survival data or recurrence data in clinical
trials of cancer therapies. In 1996, the FDA adopted a policy under which BLAs
or NDAs for cancer therapies may be submitted and considered for approval on the
basis of data from clinical trials showing, for example, partial tumor
shrinkage. Additionally, in November 1997, the Federal Food, Drug, and Cosmetic
Act was amended to codify certain FDA programs intended to expedite approval of
new drugs and biologics for the treatment of serious and life-threatening
diseases (the "FDCA Amendment"). In the past, the FDA has deemed cancer a
serious and life-threatening disease. It may therefore be possible under the
statutory amendments and the FDA's policy to submit a BLA or NDA for cancer
therapies on the basis of, for example, partial tumor shrinkage earlier than for
certain other types of drugs or biologics. There can be no assurance, however,
that the statutory amendments and the FDA's policy will be deemed to apply to
IDEC-Y2B8, 9-AC or any of the Company's other products, or that, if applicable,
the approval process will, in fact, be accelerated. Moreover, the accelerated
approval process does not necessarily increase the likelihood that any of the
Company's product candidates will be approved by the FDA.

Additionally, the FDCA Amendment clarified that the FDA may, in certain
circumstances, approve a new drug or biologic on the basis of data from one
clinical study together with confirmatory scientific evidence obtained before or
after approval, rather than on the basis of data from two or more clinical
studies, as is ordinarily the case. It may therefore be possible, with the FDA's
concurrence, to submit a BLA or NDA for FDA approval on the basis of data from
one clinical study. There can be no assurance, however, that the FDA will apply
the statutory amendment to any BLA or NDA for IDEC-Y2B8, 9-AC or any of the
Company's other products, or that the FDA would approve such a BLA or NDA.

Both before and after approval is obtained, violations of regulatory
requirements, including the preclinical and clinical testing process, the BLA or
NDA review process, or thereafter (including after approval) may result in
various adverse consequences, including the FDA's delay in approving or refusal
to approve a product, withdrawal of an approved product from the market, and/or
the imposition of criminal penalties against the manufacturer and/or BLA or NDA
holder. For example, BLA and NDA holders are required to report certain adverse
reactions to the FDA, and to comply with certain requirements concerning
advertising and promotional labeling for their products. Also, quality control
and manufacturing procedures must continue to conform to cGMP regulations after
approval, and the FDA periodically inspects manufacturing facilities to assess
compliance with cGMP. Accordingly, manufacturers must continue to expend time,
monies and effort in the area of production and quality control to maintain cGMP
compliance. In addition, discovery of problems may result in restrictions on a
product, manufacturer or BLA or NDA holder, including withdrawal of the product
from the market. Also, new government requirements may be established that could
delay or prevent regulatory approval of the Company's products under
development.

Orphan Drug Designation. Under the Orphan Drug Act, the FDA may grant
orphan drug designation to drugs intended to treat a "rare disease or
condition," which generally is a disease or condition that affects fewer than
200,000 individuals in the United States. Orphan drug designation must be
requested before

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<PAGE> 45

submitting a BLA or NDA. After the FDA grants orphan drug designation, the
generic identity of the therapeutic agent and its potential orphan use are
publicly disclosed by the FDA. Orphan drug designation does not convey any
advantage in, or shorten the duration of, the regulatory review and approval
process. If a product which has an orphan drug designation subsequently receives
FDA approval for the indication for which it has such designation, the product
is entitled to orphan exclusivity, i.e., the FDA may not approve any other
applications to market the same drug for the same indication, except in certain
very limited circumstances, for a period of seven years.

In 1994, the Company obtained orphan drug designation for Rituxan,
IDEC-Y2B8 and IDEC-In2B8 from the FDA to treat certain B-cell non-Hodgkin's
lymphomas (as defined on page 3). In connection with its approval by the FDA,
Rituxan has received orphan drug exclusivity in the United States. However,
there can be no assurance that IDEC-Y2B8 or IDEC-In2B8 will receive orphan drug
exclusivity for the B-cell non-Hodgkin's lymphoma indication, and it is possible
that competitors of the Company could obtain approval, and attendant orphan drug
exclusivity, for IDEC-Y2B8 or IDEC-In2B8 for the B-cell non-Hodgkin's lymphoma
indication, thus precluding the Company from marketing IDEC-Y2B8 or IDEC-In2B8
for that indication in the United States. In addition, even if the Company does
obtain orphan exclusivity for any of its compounds for B-cell non-Hodgkin's
lymphoma, there can be no assurance that competitors will not receive approval
of other, different drugs or biologics for B-cell non-Hodgkin's lymphoma.
Although obtaining FDA approval to market a product with orphan drug exclusivity
can be advantageous, there can be no assurance that the scope of protection or
the level of marketing exclusivity that is currently afforded by orphan drug
designation will remain in effect in the future.

PHARMACEUTICAL PRICING AND REIMBURSEMENT

The future revenues and profitability of biopharmaceutical companies as
well as the availability of capital may be affected by the continuing efforts of
government and third party payors to contain or reduce costs of health care
through various means. In the United States, there have been, and the Company
expects that there will continue to be, a number of federal and state proposals
to implement governmental control on pharmaceutical pricing. While the Company
cannot predict whether any such legislative or regulatory proposals will be
adopted, the adoption of such proposals could have a material adverse effect on
the Company's business, financial condition or prospects. In addition, the
Company's ability to commercialize its products successfully will depend in part
on the extent which appropriate reimbursement levels for the cost of such
products and related treatment are obtained from governmental authorities,
private health insurers and other organizations, such as HMOs. Third party
payors are increasingly challenging the prices charged for medical products and
services. Also, the trend toward managed health care in the United States and
the concurrent growth of organizations such as HMOs, which could control or
significantly influence the purchase of health care services and products, as
well as legislative proposals to reform health care or reduce government
insurance programs may all result in lower prices for the Company's products.
The cost containment measures that health care payors and providers are
instituting and the effect of any health care reform could adversely affect the
Company's ability to sell its products and may have a material adverse effect on
the Company.

EMPLOYEES

As of December 31, 1997, the Company employed 339 persons. The Company has
128 employees in research and development and 139 in manufacturing. In addition,
the Company retains approximately 100 independent contractors. None of the
Company's employees are represented by a labor union or bound by a collective
bargaining agreement. Management believes that its overall relations with its
employees are good.

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<PAGE> 46

ENVIRONMENTAL REGULATION

The Company's business involves the controlled use of hazardous materials,
chemicals and various radioactive compounds. Although the Company believes that
its safety procedures for handling and disposing of such materials comply with
the standards prescribed by state and federal regulations, the risk of
accidental contamination or injury from these materials cannot be completely
eliminated. In the event of such an accident, the Company could be held liable
for any damages that result and any such liability could exceed the resources of
the Company. The Company may incur substantial cost to comply with environmental
regulations. The Company anticipates no material capital expenditures to be
incurred for environmental compliance in fiscal year 1998. In addition, disposal
of radioactive materials used by the Company in its research efforts may only be
made at approved facilities. Approval of a site in California has been delayed
indefinitely. The Company currently stores such radioactive materials on site.

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<PAGE> 47

MANAGEMENT

Certain information about the Company's executive officers and directors as
of January 31, 1998 is set forth below:

<TABLE>
<CAPTION>
NAME AGE TITLE
- --------------------------------- ---- --------------------------------------------
<S> <C> <C>
William H. Rastetter, Ph.D....... 49 President, Chief Executive Officer and
Chairman of the Board of Directors
Antonio J. Grillo-Lopez, M.D..... 58 Senior Vice President, Medical and
Regulatory Affairs
Nabil Hanna, Ph.D................ 54 Senior Vice President, Research and
Preclinical Development
William R. Rohn.................. 54 Senior Vice President, Commercial Operations
Christopher J. Burman............ 48 Senior Vice President, Manufacturing and
Process Sciences
John Geigert, Ph.D............... 50 Vice President, Quality
Connie L. Matsui................. 44 Vice President, Planning and Resource
Development
Phillip M. Schneider............. 41 Vice President and Chief Financial Officer
Kenneth J. Woolcott.............. 39 Vice President, Secretary, General Counsel
and Licensing Executive
Charles C. Edwards, M.D.......... 74 Director
Alan Burnett Glassberg........... 60 Director
John Groom....................... 59 Director
Kazuhiro Hashimoto............... 57 Director
Franklin P. Johnson, Jr.......... 69 Director
Robert W. Pangia................. 46 Director
Bruce R. Ross.................... 56 Director
The Honorable Lynn Schenk........ 53 Director
William D. Young................. 53 Director
</TABLE>

DR. RASTETTER was appointed Chairman of the Board of Directors of the
Company on May 22, 1996. He has served as President and Chief Executive Officer
of the Company since December 1986 and Chief Financial Officer from 1988 to
1993. Dr. Rastetter has served as a Director of the Company since 1986. From
1984 to 1986, he was Director of Corporate Ventures at Genentech. From 1982 to
1984, Dr. Rastetter served in a scientific capacity at Genentech, directing the
Biocatalysis and Chemical Sciences groups. From 1975 to 1982, he held various
faculty positions at the Massachusetts Institute of Technology. Dr. Rastetter
received his Ph.D. in chemistry from Harvard University in 1975.

DR. GRILLO-LOPEZ joined the Company as Vice President, Medical and
Regulatory Affairs in November 1992 from Du Pont Merck Pharmaceutical Company
("Du Pont Merck"). In January 1996, he was promoted to Senior Vice President,
Medical and Regulatory Affairs. He was employed by Du Pont Merck from 1987 to
1992, where he most recently was Executive Medical Director for International
Clinical Research and Development and previously held various clinical and
medical director positions at Du Pont Merck. From 1980 to 1987, Dr. Grillo-Lopez
was a Vice President in charge of clinical therapeutics and Director of Clinical
Oncology Research at Warner Lambert Company's Parke Davis Pharmaceutical
Research Division. He trained as a hematologist and oncologist at the University
of Puerto Rico School of Medicine, San Juan, where he received his M.D. and
subsequently held faculty appointments. He has been an adjunct associate
professor in the Department of Medicine (Hematology and Medical Oncology) at the
University of Michigan Medical School, was a founder of the Puerto Rico Society
of Hematology and the Latin American Society of Hematology, and is a fellow of
the International Society of Hematology and the Royal Society of Medicine
(London).

DR. HANNA joined the Company in February 1990 as Vice President, Research
and Preclinical Development. In 1993, Dr. Hanna was promoted to Senior Vice
President, Research and Preclinical Development. From 1981 to 1990, Dr. Hanna
served as Associate Director and then Director of the

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<PAGE> 48

Department of Immunology at SmithKline Beecham focusing on autoimmune and
chronic inflammatory diseases. From 1978 to 1981, he was a research scientist at
the NCI-Frederick Cancer Research Center, where he studied the role of immune
system cells in host defenses against cancer. From 1973 to 1978, Dr. Hanna was a
lecturer in the Department of Immunology at the Hebrew University Medical School
in Israel, where he received his Ph.D. in immunology. Pursuant to the Company's
agreement with CNI, Dr. Hanna is a director of CNI.

MR. ROHN joined the Company in August 1993 as Senior Vice President,
Commercial and Corporate Development. Prior to joining the Company, Mr. Rohn was
employed by Adria Laboratories ("Adria"), from 1984 until August 1993, most
recently as Senior Vice President of Sales and Marketing with responsibilities
for strategic and commercial partnerships as well as all sales and marketing
functions in the United States. Prior to Adria, Mr. Rohn held marketing and
sales management positions at Abbott Laboratories, Warren-Teed Pharmaceuticals,
Miles Laboratories and Mead Johnson Laboratories. Mr. Rohn received a B.A. in
Marketing from Michigan State University.

MR. BURMAN joined the Company in May 1992 as Vice President, Manufacturing
Sciences and has served as Senior Vice President, Manufacturing and Process
Sciences since December 1997. He previously served from 1989 to 1992 as Director
of Manufacturing Technology at Life Sciences International. From 1985 to 1989,
he was t-PA Operations and Technical Services Manager at Genentech, where he was
responsible for the start-up of the t-PA manufacturing facility and
commercial-scale manufacturing operations. From 1967 to 1985, he held a series
of positions at Wellcome Biotech Ltd., culminating in responsibility for
worldwide cell culture manufacturing operations. Mr. Burman holds a B.Sc. with
honors in Applied Biology from the Council for National Academic Awards in the
United Kingdom. He also holds graduate qualifications in Industrial
Microbiology.

DR. GEIGERT joined the Company in May 1996 as Vice President, Quality. He
previously served from 1991 to May 1996 as Vice President, Quality Control at
Immunex Corporation, a biotechnology company. From 1973 to 1991, he was employed
by Cetus Corporation where he served most recently as Director of Quality
Control and Product Evaluation. Dr. Geigert holds a B.S. degree in chemistry
from Washington State University and a Ph.D. in organic chemistry/analytical
chemistry from Colorado State University.

MS. MATSUI joined the Company in November 1992 as Senior Director, Planning
and Resource Development with primary responsibility for strategic planning and
human resources. In December 1994, Ms. Matsui was promoted to Vice President,
Planning and Resource Development. Ms. Matsui's current responsibilities include
investor relations, corporate communications, human resources, project
management and strategic planning. As a consultant during 1992, Ms. Matsui
assisted in the planning and implementation of the Company's unification from
sites in Northern and Southern California to its present site in San Diego. From
1977 to 1991, she served in a variety of marketing and general management
positions at Wells Fargo Bank including Vice President and Manager responsible
for Consumer Retirement Programs and Vice President and Manager in charge of
company-wide Employee Relations and Communications. Ms. Matsui received her B.A.
and M.B.A. from Stanford University.

MR. SCHNEIDER joined the Company in February 1987 as Director, Finance and
Administration and served as Senior Director, Finance and Administration from
1990 to 1991. In 1991, he became Vice President, Finance and Administration and
in 1996 he was appointed Vice President and Chief Financial Officer. From 1984
to 1987, Mr. Schneider served as the Manager of Financial Reporting and as a
Senior Analyst for Syntex Laboratories. He received a B.S. in biochemistry from
University of California, Davis, received his M.B.A. at the University of
Southern California and earned his C.P.A. qualifications while working for KPMG
Peat Marwick LLP as a Senior Accountant.

MR. WOOLCOTT joined the Company in March 1989 as Intellectual Property
Counsel. In 1990, he became Intellectual Property and Licensing Counsel. Mr.
Woolcott was promoted to Deputy General Counsel in 1991 and General Counsel in
1992. In 1993, Mr. Woolcott was appointed Secretary of the Company. In 1994, he
was promoted to Vice President, Secretary, General Counsel & Licensing
Executive. From 1985 to 1987, he served as Patent Counsel and Associate Counsel
at Hybritech, Inc. From 1987 to 1989, he was engaged in the private practice of
law in Seattle, Washington. Mr. Woolcott received a B.S. in biochemistry from
Pacific Lutheran University and his J.D. from George Washington University.

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<PAGE> 49

DR. EDWARDS is the retired President and Chief Executive Officer of Scripps
Institution of Medicine and Science (the "Institute"). Dr. Edwards joined the
Institution in 1991 and retired in 1994. Dr. Edwards served as the President and
Chief Executive Officer of Scripps Clinic and Research Foundation from 1977 to
1991. Previously, Dr. Edwards held a number of positions with private, public
and governmental entities including Commissioner of the FDA and several
positions with the American Medical Association. Dr. Edwards is director of
three other publicly traded companies, Bergen Brunswig Corporation, Molecular
Biosystems, Inc. and Northern Trust of California. He received his B.S., M.D.
and Honorary Degree, Doctor of Science from the University of Colorado and
received his M.S. in Surgery from the University of Minnesota. Dr. Edwards has
served as a Director of the Company since May 1995.

DR. GLASSBERG is Associate Director of Clinical Care and Director of
General Oncology at the University of California San Francisco Cancer Center,
and also serves as Director of Hematology and Medical Oncology at Mount Zion
Medical Center in San Francisco, California. Dr. Glassberg has been associated
with the University of California, San Francisco since 1970 and is currently a
Clinical Professor of Medicine. He received his M.D. from the Medical University
of South Carolina in Charleston. Dr. Glassberg has served as a Director of the
Company since February 1997.

MR. GROOM has been President, Chief Executive Officer, and a Director of
Elan Corporation plc, a public company registered in Ireland, since July 1996.
Mr. Groom served as the President and Chief Executive Officer of Athena
Neurosciences, Inc., a biotechnology company ("Athena"), from 1987 to June 1996
prior to Athena's acquisition by Elan Corporation. From 1960 to 1985, Mr. Groom
was employed by Smith Kline & French Laboratories ("SK&F"), the pharmaceutical
division of the former SmithKline Beckman Corporation. He held a number of
positions at SK&F, including: President of SK&F International from 1980 to 1985.
Mr. Groom has served as Chairman of the International Section of the
Pharmaceutical Manufacturers Association. He serves as a Director of Ligand
Pharmaceuticals Incorporated and as a public trustee to the Research Foundation
of the American Academy of Neurology. Mr. Groom is a Fellow of the Association
of Certified Accountants (U.K.) and has served as a Director of the Company
since September 1992.

MR. HASHIMOTO has been, since 1981, Director of Research and Development of
Zenyaku, a private pharmaceutical company in Tokyo, Japan, and an investor in
the Company. Mr. Hashimoto was promoted to President of Zenyaku in July 1994. He
has served on Zenyaku's board of directors since 1977, is a director of two
privately held companies and sits on the Board of Trustees of Tamagawa Gakuen
University. Mr. Hashimoto has served as a Director of the Company since July
1991.

MR. JOHNSON has been, since 1967, the general partner of Asset Management
Partners, an investor in the Company. Mr. Johnson is also Chairman of the Board
of Book and Babbage, Inc., and a director of Amgen, Inc., Applied Microcircuit
Corporation and three privately held companies. Mr. Johnson has served as a
Director of the Company since 1986.

MR. PANGIA has worked in investment banking for 20 years and is currently
self-employed in that capacity. Most recently, he served as Executive Vice
President and Director of Investment Banking for PaineWebber Incorporated of New
York ("PaineWebber"). He held other various senior management positions at
PaineWebber including member of the board of directors of PaineWebber, Inc.,
Chairman of the board of directors of PaineWebber Properties, Inc., member of
PaineWebber's executive and operating committees, chairman of the equity
commitment committee and member of the debt commitment committee. Prior to his
positions at PaineWebber, Mr. Pangia held other senior positions including
Managing Director in Investment Banking for Drexel Burnham Lambert of New York
and Vice President of Investment Banking for Kidder, Peabody & Co. of New York.
Mr. Pangia has served as a Director of the Company since September 1997.

MR. ROSS is currently President of Cancer Rx, a health care consulting
firm. Immediately prior to launching Cancer Rx, Mr. Ross was Chief Executive
Officer of the National Comprehensive Cancer Network, an association of fifteen
of the largest cancer centers in the United States. He previously held senior
management positions, during a 27-year career, at Bristol-Myers Squibb,
including Senior Vice President, Policy, Planning and Development, Bristol-Myers
Squibb Pharmaceutical Group and President, Bristol-Myers

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<PAGE> 50

Squibb U.S. Pharmaceutical Group. Mr. Ross currently serves as a director for
Fox Chase Cancer Center and Sugen, Inc. He received his B.S. from Syracuse
University and later was a Bristol-Myers Scholar at the Yale School of
Organization and Management. Mr. Ross has served as a Director of the Company
since July 1997.

MS. SCHENK is currently an attorney in private practice and previously
served as the U.S. Congresswoman for the 49th District of the State of
California from 1993 to 1995. She worked as an attorney in private practice from
1983 to 1993 and served as the California Secretary of Business, Transportation
and Housing from 1980 to 1983. Ms. Schenk is also a director of Cal Fed Bank.
She received her B.A. in Political Science from the University of California at
Los Angeles, earned her J.D. from the University of San Diego and attended the
London School of Economics. Ms. Schenk has served as a Director of the Company
since May 1995.

MR. YOUNG is currently Chief Operating Officer of Genentech. Mr. Young
joined Genentech in 1980 as Director of Manufacturing and Process Sciences and
became Vice President in 1983. He was promoted to Senior Vice President in 1989
where he was responsible for Process Sciences, Manufacturing, Engineering,
Quality, Regulatory Affairs, Product Development and Pharmacological Sciences.
In 1986, Mr. Young was promoted to Executive Vice President. He became Chief
Operating Officer in 1997, taking on the additional responsibilities Medical
Affairs and Business Development and Sales and Marketing. Prior to joining
Genentech, Mr. Young was with Eli Lilly & Co., where he held several positions
in pharmaceutical engineering, antibiotic process development and manufacturing
management. Mr. Young holds a B.S. in Chemical Engineering from Purdue
University and an M.B.A. from Indiana University. He was elected to the National
Academy of Engineering in 1993 for his contributions to biotechnology. Mr. Young
is also a director of Energy Biosystems, Inc. Mr. Young has served as a Director
of the Company since May 1997.

49
<PAGE> 51

PRINCIPAL STOCKHOLDERS

The following table sets forth certain information known to the Company
with respect to the beneficial ownership of the Company's Common Stock as of
January 31, 1998, by (i) all persons who are beneficial owners of five percent
or more of the Company's Common Stock, (ii) each director; (iii) certain
executive officers and (iv) all current directors and executive officers of the
Company as a group.

<TABLE>
<CAPTION>
PERCENTAGE OF SHARES
BENEFICIALLY OWNED(1)
SHARES ----------------------
BENEFICIALLY BEFORE AFTER
NAME AND ADDRESS OF BENEFICIAL OWNER OWNED OFFERING OFFERING
- ------------------------------------------------------------- ------------ -------- --------
<S> <C> <C> <C>
Genentech, Inc. (2).......................................... 1,490,793 7.1% 6.4%
One DNA Way
South San Francisco, California 94080
American Century Investment Management, Inc.................. 1,418,800 7.2% 6.6%
4500 Main Street, 15th Floor
Kansas City, MO 64111
Oracle Partners, L.P......................................... 1,250,000 6.4% 5.8%
712 Fifth Avenue, 45 Floor
New York, New York 10019
Dean Witter InterCapital Inc. (3)............................ 1,048,000 5.3% 4.8%
Two World Trade Center, 71st Floor
New York, NY 10048
Charles C. Edwards, M.D. (4)................................. 33,500 * *
John Geigert, Ph.D.(5)....................................... 28,224 * *
Alan B. Glassberg, M.D. (6).................................. 22,500 * *
Antonio J. Grillo-Lopez, M.D. (7)............................ 171,946 * *
John Groom (8)............................................... 42,500 * *
Nabil Hanna, Ph.D. (9)....................................... 293,507 1.5% 1.3%
Kazuhiro Hashimoto (10)...................................... 691,667 3.5% 3.2%
Franklin P. Johnson, Jr. (11)................................ 81,737 * *
Robert W. Pangia (12)........................................ 18,500 * *
William H. Rastetter, Ph.D. (13)............................. 513,371 2.6% 2.3%
William R. Rohn (14)......................................... 173,491 * *
Bruce R. Ross (15)........................................... 17,500 * *
The Honorable Lynn Schenk (16)............................... 34,500 * *
William D. Young (17)........................................ 1,490,793 7.1% 6.4%
All directors and executive officers as a group (18 persons)
(3 through 18)............................................. 4,177,141 18.3% 16.8%
</TABLE>

- ---------------

* Less than 1%.

(1) Percentage of beneficial ownership is calculated assuming 19,630,694 shares
of Common Stock were outstanding on January 31, 1998. Beneficial ownership
is determined in accordance with the rules of the Commission and generally
includes voting or investment power with respect to securities. Shares of
Common Stock subject to options and warrants currently exercisable or
exercisable within 60 days after January 31, 1998, as well as Nonvoting
Convertible Preferred Stock, are deemed outstanding for computing the
percentage of the person holding such options but are not deemed
outstanding for computing the percentage of any other person. Except as
indicated by footnote, and subject to community property laws where
applicable, the persons named in the table have sole voting and investment
power with respect to all shares of Common Stock shown as beneficially
owned by them.

(2) Includes Nonvoting Convertible Preferred Stock convertible into 1,490,793
shares held by Genentech. Mr. Young, a director of the Company, disclaims
beneficial ownership of the Nonvoting Convertible Preferred Stock held by
Genentech. See "Description of Capital Stock -- Preferred Stock."

50
<PAGE> 52

(3) Dean Witter InterCapital Inc. is a wholly-owned subsidiary of Morgan
Stanley, Dean Witter, Discover & Co., an affiliate of one of the
Underwriters of this offering.

(4) Includes options to purchase 32,500 shares held by Dr. Edwards.

(5) Includes options to purchase 27,968 shares held by Dr. Geigert.

(6) Includes options to purchase 22,500 shares held by Dr. Glassberg.

(7) Includes options to purchase 161,998 shares held by Dr. Grillo-Lopez.

(8) Includes options to purchase 42,500 shares held by Mr. Groom.

(9) Includes options to purchase 281,095 shares held by Dr. Hanna.

(10) Includes 666,667 shares held by Zenyaku. Mr. Hashimoto, a director of the
Company, disclaims beneficial ownership of such shares. Includes options to
purchase 25,000 shares held by Mr. Hashimoto.

(11) Includes 34,303 shares beneficially owned by Asset Management Partners. Mr.
Johnson, a director of the Company, is the General Partner of Asset
Management Partners. Mr. Johnson disclaims beneficial ownership of such
shares except to the extent of his pecuniary interest arising from his
interest in Asset Management Partners. Includes options to purchase 25,000
shares held by Mr. Johnson.

(12) Includes options to purchase 18,500 shares held by Mr. Pangia.

(13) Includes options to purchase 415,719 shares held by Dr. Rastetter.

(14) Includes options to purchase 146,266 shares held by Mr. Rohn.

(15) Includes options to purchase 17,500 shares held by Mr. Ross.

(16) Includes options to purchase 32,500 shares held by Ms. Schenk.

(17) Includes Nonvoting Convertible Preferred Stock convertible into
approximately 1,490,793 shares held by Genentech. Mr. Young, a director of
the Company, disclaims beneficial ownership of the Nonvoting Convertible
Stock held by Genentech.

(18) Includes options to purchase 1,699,280 shares and Nonvoting Convertible
Preferred Stock convertible into 1,490,793 shares of Common Stock.

51
<PAGE> 53

DESCRIPTION OF CAPITAL STOCK

The authorized capital stock of the Company consists of 50,000,000 shares
of Common Stock and 8,000,000 shares of Preferred Stock.

COMMON STOCK

As of January 31, 1998, there were 19,630,694 shares of Common Stock
outstanding. See "Capitalization." The stock is held by 429 stockholders of
record. There will be 21,630,694 shares of Common Stock outstanding after giving
effect to the sale of the shares of Common Stock offered hereby (assuming no
exercise of the Underwriters' over-allotment option). The holders of Common
Stock are entitled to one vote for each share held of record on all matters
submitted to a vote of the stockholders. Subject to preferential rights with
respect to any outstanding Preferred Stock, holders of Common Stock are entitled
to receive ratably such dividends, if any, as may be declared by the Board of
Directors out of funds legally available therefor. In the event of a
liquidation, dissolution or winding up of the Company, the holders of Common
Stock are entitled to share ratably in all assets remaining after payment of
liabilities and satisfaction of preemptive rights. The Common Stock has no
conversion rights or other subscription rights. There are no redemption or
sinking fund provisions applicable to the Common Stock. The outstanding shares
of Common Stock are, and the Common Stock to be outstanding upon completion of
the offering will be, fully paid and nonassessable.

PREFERRED STOCK

As of January 31, 1998, there were 227,514 shares of Preferred Stock
outstanding. Pursuant to the Company's Certificate of Incorporation, the Board
of Directors is authorized to issue up to an aggregate of 8,000,000 shares of
Preferred Stock in one or more series and to fix the rights, preferences,
privileges and restrictions, including the dividend rights, conversion rights,
voting rights, rights and terms of redemption, redemption price or prices,
liquidation preferences and the number of shares constituting any series or the
designations of such series, without any further vote or action by the
stockholders. The issuance of Preferred Stock in certain circumstances may have
the effect of delaying, deferring, or preventing a change in control of the
Company without further actions of the stockholders. The issuance of Preferred
Stock with voting and conversion rights may adversely affect the voting power of
the holders of Common Stock, including the loss of voting control to others.

The Company issued 100,000 shares of its Series A-1 Nonvoting Convertible
Preferred Stock ("Series A-1 Preferred Stock") in April 1995, 37,521 shares of
its Series A-2 Nonvoting Convertible Preferred Stock ("Series A-2 Preferred
Stock") in August 1995 and 22,993 shares of its Series A-3 Nonvoting Convertible
Preferred Stock ("Series A-3 Preferred Stock") in March 1996, to Genentech
pursuant to the terms of a preferred stock purchase agreement. Each share of
Series A-1, A-2 and A-3 Preferred Stock is convertible at any time into 10
shares of Common Stock. In December 1997 and January 1998, Genentech converted
15,500 shares and 17,500 shares of Series A-1 Preferred Stock, respectively,
into 330,000 shares of the Company's Common Stock.

In May 1996, the Company issued 100,000 shares of its Series A-6 Nonvoting
Convertible Preferred Stock ("Series A-6 Preferred Stock") to Genentech pursuant
to the terms of a preferred stock purchase agreement. Each share of Series A-6
Preferred Stock is convertible into approximately 2.16 shares of Common Stock.

OPTIONS

As of January 31, 1998, options to purchase 3,705,119 and 197,500 shares of
Common Stock were outstanding under its 1988 Employee Stock Option Plan and its
1993 Non-Employee Directors Stock Option Plan, respectively, 2,336,477 of which
were exercisable in total on that date.

52
<PAGE> 54

Common Stock. The Company has the right to settle the capped call option by
receiving cash or stock. The capped call option which the Company purchased is
expected to be settled, if exercised, with cash paid to the Company in an amount
equal to the difference between the strike price and the market price, subject
to caps which will limit the total amount of cash the Company could receive.

Simultaneously, the Company sold to the same financial institution a call
option, exercisable only at maturity, entitling the financial institution to
purchase from the Company up to 900,000 shares of the Company's Common Stock at
a certain strike price per share. The Company has the right to settle the call
option with cash or stock and, if exercised, the Company expects to settle the
call option by issuing up to 900,000 shares of the Company's Common Stock to the
financial institution. The financial institution has advised the Company that it
has engaged, and may continue to engage, in transactions, including buying and
selling shares of the Company's Common Stock, to offset its risk relating to the
call option, which could affect the market price of the Company's Common Stock.

STOCKHOLDER RIGHTS AGREEMENT

In July 1997, the Company's Board of Directors declared a dividend of one
preferred stock purchase right ("Right") for each outstanding share of the
Company's Common Stock. Each Right represents the right to purchase one
one-thousandth of a share of Series X Junior Participating Preferred Stock at an
exercise price of $200, subject to adjustment, and will be exercisable only if a
person or group acquires 15% or more of the Company's Common Stock or announces
a tender offer for 15% or more of the Company's Common Stock. If a person
acquires 15% or more of Company's Common Stock all Rightsholders, except the
acquiring person, will be entitled to buy shares of the Company's Common Stock
at a discount. Each Series X Junior Participating Preferred Share will be
entitled to an aggregate dividend of 1,000 times the dividend declared per share
of Common Stock. The Board of Directors may terminate the Rights Plan at any
time or redeem the Rights at $.001 per Right, prior to the time a person
acquires more than 15% of the Company's common stock. The Rights will expire in
July 2007.

REGISTRATION RIGHTS

Under the terms of the 1992 Amended and Restated Registration Rights
Agreement among the Company and the holders of the securities registrable
thereunder (the "1992 Registrable Securities"), if the Company proposes to
register any of its securities under the Act, either for its own account or for
the account of other security holders exercising registration rights, such
holders are entitled to notice of such registration and are entitled to include
1992 Registrable Securities therein. These rights are subject to certain
conditions and limitations, among them the right of the underwriters of an
offering subject to the registration to limit the number of shares included in
such registration. Following this offering, the holders of approximately 666,667
shares of Common Stock, or their transferees, will be entitled to certain rights
with respect to the registration of their 1992 Registrable Securities under the
Securities Act. The holders of the 1992 Registrable Securities may also require
the Company on not more than two occasions to file a registration statement
under the Act at its expense with respect to their shares of Common Stock (and
on not more than one occasion to file a registration statement under the Act at
its expense with respect to shares issuable upon the exercise of certain
warrants), and the Company is required to use its best efforts to effect such
registration, subject to certain conditions and limitations. Further, certain of
such holders may require the Company to file additional registration statements
on Form S-3, subject to certain conditions and limitations. The holders of the
1992 Registrable Securities have waived their registration rights in connection
with the offering made hereby.

Under the terms of the 1995 Registration Rights Agreement among the Company
and Genentech, if the Company proposes to register any of its securities under
the Securities Act, either for its own account or for the account of other
security holders exercising registration rights, Genentech is entitled to notice
of such registration and is entitled to include 1995 Registrable Securities
therein. These rights are subject to certain conditions and limitations, among
them the right of the underwriters of an offering subject to the registration to
limit the number of shares included in such registration. Genentech has waived
its piggyback registration rights in connection with the offering made hereby.
Genentech may also require the Company to file a registration statement under
the Act at its expense with respect to its 1995 Registrable Securities, and the

53
<PAGE> 55

Company is required to use its best efforts to effect such registration, subject
to certain conditions and limitations.

TRANSFER AGENT AND REGISTRAR

The transfer agent and registrar for the Company's Common Stock is
ChaseMellon Shareholder Services, LLC 400 S. Hope Street, Fourth Floor, Los
Angeles, CA 90071.

54
<PAGE> 56

UNDERWRITERS

Under the terms and subject to the conditions contained in an Underwriting
Agreement dated the date hereof (the "Underwriting Agreement"), the underwriters
named below (the "Underwriters") have severally agreed to purchase, and the
Company has agreed to sell to them, severally, the respective number of shares
of Common Stock set forth opposite their names below:

<TABLE>
<CAPTION>
NUMBER OF
NAME SHARES
-------------------------------------------------------------------------- ---------
<S> <C>
Morgan Stanley & Co. .....................................................
NationsBanc Montgomery Securities LLC.....................................
---------
Total...................................................................
=========
</TABLE>

The Underwriting Agreement provides that the obligations of the several
Underwriters to pay for and accept delivery of the shares of Common Stock
offered hereby are subject to the approval of certain legal matters by their
counsel, and to certain other conditions. The Underwriters are obligated to take
and pay for all of the shares of Common Stock offered hereby (other than those
covered by the over-allotment option described below) if any such shares are
taken.

The Underwriters initially propose to offer part of the shares of Common
Stock offered hereby directly to the public at the public offering price set
forth on the cover page hereof and part to certain dealers at a price that
represents a concession not in excess of $ per share under the public offering
price. Any Underwriter may allow, and such dealers may reallow, a concession not
in excess of $ per share to other Underwriters or to certain other dealers.

The Company and the Underwriters have agreed to indemnify each other
against certain liabilities, including liabilities under the Securities Act.

The Company has granted to the Underwriters an option, exercisable for 30
days from the date of this Prospectus, to purchase up to 300,000 additional
shares of Common Stock at the public offering price set forth on the cover page
hereof, less underwriting discounts and commission. The Underwriters may
exercise such option to purchase solely for the purpose of covering
over-allotments, if any, made in connection with the offering of the shares of
Common Stock offered hereby. To the extent such option is exercised, each
Underwriter will become obligated, subject to certain conditions, to purchase
approximately the same percentage of such additional shares of Common Stock as
the number set forth next to such Underwriter's name in the preceding table
bears to the total number of shares of Common Stock offered by the Underwriters
hereby.

The Underwriters have informed the Company that they do not intend to
confirm sales to accounts over which they exercise discretionary authority.

The Company and its executive officers and directors and certain
stockholders of the Company have agreed not to (a) offer, pledge, lend, sell,
contract to sell, sell any option or contract to purchase, purchase any option
or contract to sell, grant any option, right or warrant to purchase, or
otherwise transfer or dispose of, directly or indirectly, any shares of Common
Stock or any securities convertible into or exercisable or exchangeable for
Common Stock, or (b) enter into any swap or other arrangement that transfers to
another, in whole or in part, any of the economic consequences of ownership of
the Common Stock, whether any such transaction described in clause (a) or (b)
above is to be settled by delivery of Common Stock or such other securities, in
cash or otherwise for a 90-day period after the date of this Prospectus, without
the prior written

55
<PAGE> 57

consent of Morgan Stanley & Co. Incorporated, except that the Company may,
without such consent, grant options or issue stock upon the exercise of
outstanding stock options, pursuant to the Company's stock option plans, and
issue stock upon exercise of the warrants.

In order to facilitate the offering of the Common Stock, the Underwriters
may engage in transactions that stabilize, maintain or otherwise affect the
price of the Common Stock. Specifically, the Underwriters may over-allot in
connection with the offering, creating a short position in the Common Stock for
their own account. In addition, to cover over-allotments or to stabilize the
price of the Common Stock, the Underwriters may bid for, and purchase, shares of
Common Stock in the open market. Finally, the underwriting syndicate may reclaim
selling concessions allowed to an underwriter or a dealer for distributing the
Common Stock in the offering, if the syndicate repurchases previously
distributed Common Stock in transactions to cover syndicate short positions, in
stabilization transactions or otherwise. Any of these activities may stabilize
or maintain the market price of the Common Stock above independent market
levels. The Underwriters are not required to engage in these activities, and may
end any of these activities at any time. The Underwriters and dealers may engage
in passive market making transactions in the Common Stock in accordance with
Rule 103 of Regulation M promulgated by the Commission. In general, a passive
market maker may not bid for, or purchase, the Common Stock at a price that
exceeds the highest independent bid. In addition, the net daily purchases made
by any passive market maker generally may not exceed 30% of its average daily
trading volume in the Common Stock during a specified two month prior period, or
200 shares, whichever is greater. A passive market maker must identify passive
market making bids as such on the Nasdaq electronic inter-dealer reporting
system. Passive market marking may stabilize or maintain the market price of the
Common Stock above independent market levels. Underwriters and dealers are not
required to engage in passive market making and may end passive market making
activities at any time.

Dean Witter Intercapital Inc., the beneficial owner of 1,048,000 shares of
the Company's Common Stock, is a wholly-owned subsidiary of Morgan Stanley, Dean
Witter, Discover & Co., an affiliate of one of the Underwriters in this
offering.

LEGAL MATTERS

Certain legal matters with respect to the validity of the shares of Common
Stock offered hereby are being passed upon for the Company by Brobeck, Phleger &
Harrison LLP, Palo Alto, California. Certain legal matters are being passed upon
for the Underwriters by Gunderson Dettmer Stough Villeneuve Franklin &
Hachigian, LLP, Menlo Park, California.

EXPERTS

The consolidated financial statements of IDEC Pharmaceuticals Corporation
and subsidiary as of December 31, 1996 and 1997, and for each of the years in
the three-year period ended December 31, 1997, have been included herein and in
the Registration Statement in reliance upon the report of KPMG Peat Marwick LLP,
independent certified public accountants, appearing elsewhere herein and upon
the authority of said firm as experts in accounting and auditing.

56
<PAGE> 58

AVAILABLE INFORMATION

This Prospectus, which constitutes a part of a Registration Statement on
Form S-3 (the "Registration Statement") filed by the Company with the Commission
under the Securities Act, omits certain of the information set forth in the
Registration Statement. Reference is hereby made to the Registration Statement
and to the exhibits thereto for further information with respect to the Company
and the securities offered hereby. Copies of the Registration Statement and the
exhibits thereto are on file at the offices of the Commission and may be
obtained upon payment of the prescribed fee or may be examined without charge at
the public reference facilities of the Commission described below.

The Company is subject to the informational requirements of the Exchange
Act and in accordance therewith, files reports, proxy statements and other
information with the Commission. Such reports, proxy statements and other
information filed by the Company with the Commission can be inspected and copied
at the public reference facilities maintained by the Commission at Room 1024
Judiciary Plaza, 450 Fifth Street, N.W., Room 1024, Washington, D.C. 20549, and
the Commission's regional offices located at Seven World Trade Center, Suite
1300, New York, New York 10048 and Citicorp Center, 500 West Madison Street,
Suite 1400, Chicago, Illinois 60661. The Commission maintains an Internet
website that contains reports, proxy statements and information statement and
other information regarding registrants that file electronically with the
Commission. The address of such website is http://www.sec.gov. Copies of such
material can also be obtained from the Public Reference Section of the
Commission at 450 Fifth Street, N.W., Washington, D.C. 20549, upon payment of
prescribed rates. The Company's Common Stock is quoted on the Nasdaq National
Market. Reports, proxy statements and other information concerning the Company
may be inspected at the National Association of Securities Dealers, Inc. at 1735
K Street, N.W., Washington, D.C. 20006.

57
<PAGE> 59

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

<TABLE>
<CAPTION>
PAGE
----
<S> <C>
Report of KPMG Peat Marwick LLP....................................................... F-2
Consolidated Balance Sheets........................................................... F-3
Consolidated Statements of Operations................................................. F-4
Consolidated Statements of Stockholders' Equity....................................... F-5
Consolidated Statements of Cash Flows................................................. F-6
Notes to Consolidated Financial Statements............................................ F-7
</TABLE>

F-1
<PAGE> 60

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

INDEPENDENT AUDITORS' REPORT

The Board of Directors and Stockholders
IDEC Pharmaceuticals Corporation:

We have audited the accompanying consolidated balance sheets of IDEC
Pharmaceuticals Corporation and subsidiary as of December 31, 1996 and 1997, and
the related consolidated statements of operations, stockholders' equity, and
cash flows for each of the years in the three-year period ended December 31,
1997. These consolidated financial statements are the responsibility of the
Company's management. Our responsibility is to express an opinion on these
consolidated financial statements based on our audits.

We conducted our audits in accordance with generally accepted auditing
standards. Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also includes
assessing the accounting principles used and significant estimates made by
management, as well as evaluating the overall financial statement presentation.
We believe that our audits provide a reasonable basis for our opinion.

In our opinion, the consolidated financial statements referred to above
present fairly, in all material respects, the financial position of IDEC
Pharmaceuticals Corporation and subsidiary as of December 31, 1996 and 1997, and
the results of their operations and their cash flows for each of the years in
the three-year period ended December 31, 1997, in conformity with generally
accepted accounting principles.

KPMG Peat Marwick LLP
San Diego, California
February 6, 1998

F-2
<PAGE> 61

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

CONSOLIDATED BALANCE SHEETS
(IN THOUSANDS)

<TABLE>
<CAPTION>
DECEMBER 31,
-------------------
1996 1997
-------- --------
<S> <C> <C>
ASSETS
Current assets:
Cash and cash equivalents.............................................. $ 25,337 $ 34,847
Securities available-for-sale.......................................... 53,390 34,810
Contract revenue receivables, net...................................... 3,635 3,971
Due from related party, net............................................ 732 -
Inventories............................................................ 4,384 4,134
Prepaid expenses and other current assets.............................. 3,337 1,431
---- ----
Total current assets................................................ 90,815 79,193
Property and equipment, net.............................................. 21,453 23,449
Investment and other assets.............................................. 761 3,371
---- ----
$113,029 $106,013
==== ====

LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
Current portion of notes payable....................................... $ 3,830 $ 3,908
Accounts payable....................................................... 3,106 1,626
Accrued expenses....................................................... 5,951 6,382
Due to related party, net.............................................. - 870
Deferred revenue....................................................... - 6,646
---- ----
Total current liabilities........................................... 12,887 19,432
---- ----
Notes payable, less current portion...................................... 5,015 3,886
Deferred rent............................................................ 1,513 2,016
Due to related party, noncurrent......................................... 1,000 -
Commitments
Stockholders' equity:
Convertible preferred stock, $.001 par value, 8,000 shares authorized;
330 shares and 245 shares issued and outstanding at December 31,
1996 and 1997, respectively; $26,938 and $19,225 liquidation value
at December 31, 1996 and 1997, respectively......................... - -
Common stock, $.001 par value, 50,000 shares authorized; 18,059 shares
and 19,356 shares issued and outstanding at December 31, 1996 and
1997, respectively.................................................. 18 19
Additional paid-in capital............................................. 176,448 179,956
Unrealized gains (losses) on securities available-for-sale............. (37) 57
Accumulated deficit.................................................... (83,815) (99,353)
---- ----
Total stockholders' equity.......................................... 92,614 80,679
---- ----
$113,029 $106,013
==== ====
</TABLE>

See accompanying notes to consolidated financial statements.

F-3
<PAGE> 62

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

CONSOLIDATED STATEMENTS OF OPERATIONS
(IN THOUSANDS, EXCEPT PER SHARE DATA)

<TABLE>
<CAPTION>
YEARS ENDED DECEMBER 31,
---------------------------------
1995 1996 1997
-------- ------- --------
<S> <C> <C> <C>
Revenues:
Revenues from unconsolidated joint business............... $ -- $ -- $ 9,266
Contract revenues......................................... 12,136 15,759 11,840
License fees.............................................. 11,500 14,250 23,500
-------- ------- --------
Total revenues (including related party revenues
of $5,500 and $27,373 in 1996 and 1997,
respectively)................................... 23,636 30,009 44,606
Operating expenses:
Manufacturing costs....................................... -- -- 18,875
Research and development.................................. 22,488 28,147 32,407
Selling, general and administrative....................... 6,112 7,298 11,320
Acquired technology rights................................ 11,437 -- --
-------- ------- --------
Total operating expenses.......................... 40,037 35,445 62,602
-------- ------- --------
Loss from operations........................................ (16,401) (5,436) (17,996)
-------- ------- --------
Other income (expense):
Interest income........................................... 1,387 3,178 3,489
Interest expense.......................................... (2,278) (2,697) (917)
Other..................................................... -- -- (114)
-------- ------- --------
Total other income (expense)...................... (891) 481 2,458
-------- ------- --------
Net loss.................................................... (17,292) (4,955) (15,538)
Convertible preferred stock dividends....................... -- (696) --
-------- ------- --------
Net loss applicable to common stock......................... $(17,292) (5,651) $(15,538)
======== ======= ========
Net loss per common share................................... $ (1.18) $ (0.34) $ (0.83)
Shares used in computing net loss per common share.......... 14,650 16,573 18,739
</TABLE>

See accompanying notes to consolidated financial statements.

F-4
<PAGE> 63

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
(IN THOUSANDS)

<TABLE>
<CAPTION>
CONVERTIBLE
PREFERRED STOCK COMMON STOCK ADDITIONAL UNREALIZED GAINS TOTAL
--------------- --------------- PAID-IN (LOSSES) ON SECURITIES ACCUMULATED STOCKHOLDERS'
SHARES AMOUNT SHARES AMOUNT CAPITAL AVAILABLE-FOR-SALE DEFICIT EQUITY
------ ------ ------- ------ ---------- ---------------------- ----------- -------------
<S> <C> <C> <C> <C> <C> <C> <C> <C>
Balance at December 31,
1994.................... -- $ -- 13,728 $ 14 $ 89,464 $(14) $ (61,568) $ 27,896
Issuance of common stock
under stock option and
employee stock purchase
plans................... -- -- 230 -- 953 -- -- 953
Issuance of series A-1 and
A-2 convertible
preferred stock pursuant
to terms of a
collaborative
agreement............... 138 -- -- -- 7,149 -- -- 7,149
Issuance of common stock
and series B convertible
preferred stock to
acquire technology
rights.................. 69 -- 1,000 1 11,436 -- -- 11,437
Issuance of common stock
for services............ -- -- 103 -- 322 -- -- 322
Amortization of fair value
change in common stock
warrants................ -- -- -- -- 680 -- -- 680
Change in unrealized gains
(losses) on securities
available-for-sale...... -- -- -- -- -- 24 -- 24
Net loss.................. -- -- -- -- -- -- (17,292) (17,292)
--- --- ------ --- -------- ---- ------- -------
Balance at December 31,
1995.................... 207 -- 15,061 15 110,004 10 (78,860) 31,169
Issuance of common stock
under stock option and
employee stock purchase
plans................... -- -- 342 -- 1,304 -- -- 1,304
Issuance of common stock
in public offering...... -- -- 2,070 2 46,275 -- -- 46,277
Issuance of common stock
for services............ -- -- 17 -- 359 -- -- 359
Issuance of common stock
from exercise of stock
warrants................ -- -- 569 1 4,754 -- -- 4,755
Issuance of series A-3 and
series A-6 convertible
preferred stock pursuant
to terms of a
collaborative
agreement............... 123 -- -- -- 12,500 -- -- 12,500
Amortization of fair value
change in common stock
warrants................ -- -- -- -- 1,252 -- -- 1,252
Change in unrealized gains
(losses) on securities
available-for-sale...... -- -- -- -- -- (47) -- (47)
Net loss.................. -- -- -- -- -- -- (4,955) (4,955)
--- --- ------ --- -------- ---- ------- -------
Balance at December 31,
1996.................... 330 -- 18,059 18 176,448 (37) (83,815) 92,614
Issuance of common stock
under stock option and
employee stock purchase
plans................... -- -- 670 1 3,508 -- -- 3,509
Issuance of common stock
from exercise of stock
warrants................ -- -- 105 -- -- -- -- --
Issuance of common stock
from conversion of
series A-1 and B
convertible preferred
stock................... (85) -- 522 -- -- -- -- --
Change in unrealized gains
(losses) on securities
available-for-sale...... -- -- -- -- -- 94 -- 94
Net loss.................. -- -- -- -- -- -- (15,538) (15,538)
--- --- ------ --- -------- ---- ------- -------
Balance at December 31,
1997.................... 245 $ -- 19,356 $ 19 $ 179,956 $ 57 $ (99,353) $ 80,679
=== === ====== === ======== ==== ======= =======
</TABLE>

See accompanying notes to consolidated financial statements.

F-5
<PAGE> 64

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

CONSOLIDATED STATEMENTS OF CASH FLOWS
(IN THOUSANDS)

<TABLE>
<CAPTION>
YEARS ENDED DECEMBER 31,
----------------------------------
1995 1996 1997
-------- -------- --------
<S> <C> <C> <C>
Cash flows from operating activities:
Net loss................................................. $(17,292) $ (4,955) $(15,538)
Adjustments to reconcile net loss to net cash used in
operating activities:
Depreciation and amortization......................... 2,401 2,643 4,010
Deferred rent......................................... 450 390 503
Other non-cash expenses............................... -- (104) (131)
Gains (losses) on sales of securities
available-for-sale.................................. 5 -- (12)
Acquired technology rights............................ 11,437 -- --
Issuance of common stock for services................. 322 359 --
Amortization of fair value change in common stock
warrants............................................ 680 1,252 --
Change in assets and liabilities:
Contract revenue receivables, net................... (621) (3,712) (336)
Due from related party, net......................... -- (732) 732
Inventories......................................... -- (4,384) 250
Prepaid expenses and other assets................... 403..... 890 2,296
Accounts payable, accrued expenses and other
liabilities...................................... 1,650... 3,570 (1,049)
Due to related party................................ -- 1,000 (130)
Deferred revenue.................................... (2,024) -- 6,646
-------- -------- --------
Net cash used in operating activities............ (2,589) (3,783) (2,759)
-------- -------- --------
Cash flows from investing activities:
Purchase of marketable securities and securities
available-for-sale.................................... (8,218) (72,771) (39,538)
Sales and maturities of marketable securities and
securities available-for-sale......................... 10,715 25,265 58,224
Purchase of property and equipment....................... (1,315) (6,301) (5,875)
Investment in Cytokine Networks, Inc..................... -- -- (3,000)
-------- -------- --------
Net cash provided by (used in) investing
activities..................................... 1,182 (53,807) 9,811
-------- -------- --------
Cash flows from financing activities:
Proceeds from notes payable.............................. 2,500 2,475 3,003
Payments on notes payable................................ (4,058) (3,440) (4,054)
Proceeds from issuance of common stock, net.............. 953 52,564 3,509
Proceeds from issuance of convertible preferred stock,
net................................................... 7,149 12,500 --
-------- -------- --------
Net cash provided by financing activities........ 6,544 64,099 2,458
-------- -------- --------
Net increase in cash and cash equivalents.................. 5,137 6,509 9,510
Cash and cash equivalents, beginning of year............... 13,691 18,828 25,337
-------- -------- --------
Cash and cash equivalents, end of year..................... $ 18,828 $ 25,337 $ 34,847
======== ======== ========
Supplemental disclosure of cash flow information --
Cash paid during the year for interest................... $ 1,518 $ 1,469 $ 952
</TABLE>

See accompanying notes to consolidated financial statements.

F-6
<PAGE> 65

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

NOTE 1: ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Business: IDEC Pharmaceuticals Corporation (the "Company") is primarily
engaged in the commercialization and research and development of targeted
therapies for the treatment of cancer and autoimmune and inflammatory diseases.

Principles of Consolidation: The consolidated financial statements include
the financial statements of IDEC Pharmaceuticals Corporation and its wholly
owned subsidiary IDEC Seiyaku. All significant intercompany balances and
transactions have been eliminated in consolidation.

Cash and Cash Equivalents: For the purposes of financial statement
presentation, the Company considers all highly liquid investments in debt
securities with original maturities of three months or less to be cash
equivalents.

Securities Available-for-Sale: Securities available-for-sale are carried at
fair value, with unrealized gains and losses, net of tax, reported as a separate
component of stockholders' equity. The cost of securities sold is based on the
specific identification method.

Inventories: Inventories are stated at the lower of cost or market. Cost is
determined in a manner which approximates the first-in, first-out (FIFO) method.
Inventories at December 31, 1997 and 1996 consists of the following (table in
thousands):

<TABLE>
<CAPTION>
1996 1997
------ ------
<S> <C> <C>
Raw materials...................................... $ 366 $1,204
Work in process.................................... - 486
Finished goods..................................... 4,018 2,444
------ ------
$4,384 $4,134
====== ======
</TABLE>

Property and Equipment: Property and equipment are stated at cost.
Depreciation of property and equipment is calculated using the straight-line
method over the estimated useful lives of the assets, generally ranging from
three to seven years. Amortization of leasehold improvements is calculated using
the straight-line method over the shorter of the lease term or the estimated
useful lives of the assets.

Fair Value of Financial Instruments: The carrying amount of cash and cash
equivalents, securities available-for-sale, contract revenue receivables,
accounts payable, accrued expenses and notes payable are considered to be
representative of their respective fair values because of the short-term nature
of those investments. A reasonable estimate of fair value is not practicable for
the liability, due to related party, at December 31, 1997, because of the
inherent difficulty of evaluating the timing of the payments.

Research and Development: All research and development expenses, including
purchased research and development, are expensed in the period incurred.
Clinical grant expenses are fully accrued upon patient enrollment.

Revenues from Unconsolidated Joint Business: Revenues from unconsolidated
joint business consists of the Company's share of the pretax operating results
generated from its joint business arrangement with Genentech, Inc.
("Genentech"), revenue from bulk Rituxan sales to Genentech, reimbursement from
Genentech of the Company's sales force and development expenses and royalty
income from F. Hoffmann-La Roche Ltd. ("Hoffmann-La Roche") and Zenyaku Kogyo
Co., Ltd. ("Zenyaku") on sales of Rituxan outside the United States and Canada.
Revenue from bulk Rituxan sales is recognized when accepted by Genentech. Under
the joint business arrangement, all U.S. sales of Rituxan and associated
expenses will be recorded in the books and accounts of Genentech with the
Company recording it's share of the pretax operating results on a quarterly
basis, as defined in the Company's collaborative agreement with Genentech (Note
7). Pretax operating results under the joint business arrangement are derived by
taking the net U.S. sales of Rituxan to

F-7
<PAGE> 66

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

third-party customers less cost of sales, third party royalty expenses,
distribution, selling and marketing expenses and joint development expenses by
the Company and Genentech.

Contract Revenues: Contract revenues consist of non-refundable research and
development funding under collaborative agreements with the Company's various
strategic partners and other funding under contractual arrangements with other
parties. Contract research and development funding generally compensates the
Company for discovery, preclinical and clinical expenses related to the
collaborative development programs for certain products of the Company and is
recognized at the time research and development activities are performed under
the terms of the collaborative agreements. Contract revenues earned in excess of
contract payments received are classified as contract revenue receivables.

License Fees: License fees consist of non-refundable fees from product
development milestone payments, the sale of license rights to the Company's
propriety gene expression technology and non-refundable fees from the sale of
product rights under collaborative development and license agreements with the
Company's strategic partners. Revenues from product development milestone
payments are recognized when the results or events stipulated in the agreement
have been achieved. License fee payments received in excess of amounts earned
are classified as deferred revenue.

Manufacturing Costs: Manufacturing costs consist of manufacturing costs
related to the production of bulk Rituxan sold to Genentech.

Stock Based Compensation: The Company's stock option and purchase plans are
accounted for under Accounting Principles Board Opinion No. 25, "Accounting for
Stock Issued to Employees" ("APB Opinion No. 25"), and the Company makes pro
forma footnote disclosures of the Company's operating results as if the Company
had adopted the fair value method under Financial Accounting standards Board
Statement No. 123, "Accounting for Stock-Based Compensation" ("Statement No.
123").

Income Taxes: Income taxes are accounted for under the asset and liability
method where deferred tax assets and liabilities are recognized for the future
tax consequences attributable to differences between the financial statement
carrying amounts of existing assets and liabilities and their respective tax
bases and net operating loss and tax credit carryforwards. Deferred tax assets
and liabilities are measured using enacted tax rates expected to apply to
taxable income in the years in which those temporary differences are expected to
be recovered or settled. The effect on deferred tax assets and liabilities of a
change in tax rates is recognized in income in the period that includes the
enactment date.

Net Loss Per Common Share: In December 1997, the Company adopted Statement
of Financial Accounting Standards No. 128 "Earnings per Share" ("Statement No.
128"). Statement No. 128 supersedes Accounting Principles Board Opinion No. 15
("APB No. 15") and replaces "primary" and "fully diluted" earnings per share
("EPS") under APB No. 15 with "basic" and "diluted" EPS. Unlike primary EPS,
basic EPS excludes the dilutive effects of options, warrants and other
convertible securities. Diluted EPS reflects the potential dilution of
securities that could share in the earnings of the Company, similar to fully
diluted EPS. The adoption of Statement No. 128 did not have a material effect on
the Company's net loss per common share for the prior years presented. Options,
warrants and other convertible securities totaling 2,855,000 shares, 4,538,000
shares and 4,181,000 shares were excluded from the computations of net loss per
common share for the years ended December 31, 1995, 1996 and 1997, respectively,
as their effect is antidilutive.

Use of Estimates: Management of the Company has made a number of estimates
and assumptions relating to the reporting of assets and liabilities and the
disclosure of contingent assets and liabilities at the date of the consolidated
financial statements and the reported amounts of revenues and expenses during
the reporting periods to prepare these consolidated financial statements in
conformity with generally accepted accounting principles. Actual results could
differ from these estimates.

F-8
<PAGE> 67

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

Reclassifications: The prior year balances in preferred stock, common stock
and additional paid-in capital have been reclassified to effect the change in
par value to $.001 per share resulting from stockholder approval in May 1997, of
a change in the state of incorporation of the Company from the State of
California to the State of Delaware. Certain other balances in 1996 and 1995
have been reclassified to conform with the presentation in 1997.

NOTE 2: SECURITIES AVAILABLE-FOR-SALE

Securities available-for-sale at December 31, 1996 and 1997 consist of the
following (tables in thousands):

<TABLE>
<CAPTION>
1996
---------------------------------------------------
GROSS GROSS
AMORTIZED UNREALIZED UNREALIZED MARKET
COSTS GAINS LOSSES VALUE
--------- ---------- ---------- -------
<S> <C> <C> <C> <C>
Corporate securities.............................. $40,227 $ 3 $(38) $40,192
Commercial paper.................................. 9,979 -- -- 9,979
Certificates of deposit........................... 1,499 -- -- 1,499
U.S. government agencies.......................... 1,722 -- (2) 1,720
------- ---- ---- -------
$53,427 $ 3 $(40) $53,390
======= ==== ==== =======
</TABLE>

<TABLE>
<CAPTION>
1997
---------------------------------------------------
GROSS GROSS
AMORTIZED UNREALIZED UNREALIZED MARKET
COSTS GAINS LOSSES VALUE
--------- ---------- ---------- -------
<S> <C> <C> <C> <C>
Corporate securities.............................. $13,672 $ 3 $(18) $13,657
Commercial paper.................................. 4,707 44 -- 4,751
Certificates of deposit........................... 5,699 -- -- 5,699
U.S. government agencies.......................... 10,675 29 (1) 10,703
------- ---- ---- -------
$34,753 $ 76 $(19) $34,810
======= ==== ==== =======
</TABLE>

The net unrealized holding gain (loss) on securities available-for-sale
included as a separate component of stockholders' equity at December 31, 1996
and 1997 totaled $(37,000) and $57,000, respectively. The gross realized gains
on sales of securities available-for-sale for the year ended December 31, 1997
totaled $12,000.

The amortized cost and estimated fair value of securities
available-for-sale at December 31, 1997, by contractual maturity are shown below
(table in thousands):

<TABLE>
<CAPTION>
AMORTIZED ESTIMATED
COST FAIR VALUE
--------- ----------
<S> <C> <C>
Due in one year or less................................ $30,105 $ 30,170
Due after one year through two years................... 2,648 2,640
Due after ten years.................................... 2,000 2,000
------- -------
$34,753 $ 34,810
======= =======
</TABLE>

F-9
<PAGE> 68

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

NOTE 3: PROPERTY AND EQUIPMENT

Property and equipment at December 31, 1996 and 1997 consists of the
following (table in thousands):

<TABLE>
<CAPTION>
1996 1997
------- -------
<S> <C> <C>
Furniture and fixtures................................... $ 1,158 $ 1,226
Machinery and equipment.................................. 11,061 13,118
Leasehold improvements................................... 16,359 18,922
Construction in progress................................. 1,480 2,667
------- -------
30,058 35,933
Accumulated depreciation and amortization................ (8,605) (12,484)
------- -------
$21,453 $23,449
======= =======
</TABLE>

NOTE 4: NOTES PAYABLE

Notes payable at December 31, 1996 and 1997, consist of the following
(table in thousands):

<TABLE>
<CAPTION>
1996 1997
------- -------
<S> <C> <C>
Prime plus 1% note (9.5% at December 31, 1997), due in monthly
installments with a final payment of $750 due at maturity in 1998,
secured by equipment, lease deed of trust, and a patent and trademark
collateral assignment.................................................. $2,710.. $ 1,361
17.74% note, due in monthly installments with a final payment of $375 due
at maturity in 1998, secured by equipment, lease deed of trust, and a
patent and trademark collateral assignment............................. 1,355.. 682
17.53% note, due in monthly installments with a final payment of $375 due
at maturity in 1999, secured by equipment, lease deed of trust, and a
patent and trademark collateral assignment............................. 1,745.. 1,149
9.32% to 10.62% capital lease obligations, due in monthly installments,
maturing 2000.......................................................... 2,263.. 1,831
8.94% note, due in monthly installments, maturing 2001, secured by
equipment.............................................................. --..... 2,771
Other notes, due in monthly installments, maturing through 1997, secured
by equipment........................................................... 772 --
------- -------
8,845 7,794
Current portion.......................................................... (3,830) (3,908)
------- -------
$ 5,015 $ 3,886
======= =======
</TABLE>

Machinery and equipment recorded under capital leases was $2,698,000, net
of accumulated depreciation of $1,188,000 at December 31, 1997.

The aggregate maturities of notes payable for each of the three years
subsequent to December 31, 1997, are as follows: 1998, $3,908,000; 1999,
$1,709,000; 2000, $1,470,000; and 2001, $707,000.

NOTE 5: 401(K) EMPLOYEE SAVINGS PLAN

The Company has a qualified 401(k) Employee Savings Plan ("401(k) Plan"),
available to substantially all employees over the age of 21. The Company may
make discretionary contributions to the 401(k) Plan, which fully vest after four
years of service by the employee. There were no discretionary contributions for
the years ended December 31, 1997, 1996 and 1995.

F-10
<PAGE> 69

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

NOTE 6: RESEARCH AND DEVELOPMENT

In December 1995, the Company and Eisai Co. Ltd. ("Eisai") entered into a
collaborative development agreement and a license agreement aimed at the
development and commercialization of humanized and PRIMATIZED anti-gp39
antibodies. Under the terms of these agreements, Eisai may provide up to
$37,500,000 in product development milestone payments and support for research
and development. Eisai will receive exclusive rights in Asia and Europe to
develop and market resulting products emerging from the collaboration, with the
Company receiving royalties on eventual product sales by Eisai. Eisai may
terminate these agreements based on a reasonable determination that the products
do not justify continued product development or marketing. Included in contract
revenues for 1995, 1996 and 1997 is $2,500,000, $5,500,000 and $2,750,000,
respectively, to fund product development, which approximates the research and
development expenses incurred under the program. Included in license fees for
the years ended December 31, 1995, 1996 and 1997, is $2,000,000, $750,000 and
$2,000,000, respectively, earned under these agreements.

In December 1994, the Company and Seikagaku Corporation ("Seikagaku")
entered into a collaborative development agreement and a license agreement aimed
at the development and commercialization of a PRIMATIZED anti-CD23 antibody.
Under the terms of these agreements, Seikagaku may provide up to $26,000,000 in
product development milestone payments and support for research and development.
The Company and Seikagaku will share co-exclusive, worldwide rights to all
products emerging from the collaboration, with the Company receiving royalties
on eventual product sales by Seikagaku. Seikagaku may terminate these agreements
based on a reasonable determination that the products do not justify continued
product development or marketing. Included in contract revenues for 1995, 1996
and 1997 is $2,500,000, $3,500,000 and $3,500,000, respectively, to fund product
development, which approximates the research and development expenses incurred
under the program. Included in license fees for the years ended December 31,
1995, 1996 and 1997, is $1,000,000, $1,000,000 and $1,500,000, respectively,
earned under these agreements.

In November 1993, the Company entered into a collaborative development
agreement and a license agreement with Mitsubishi Chemical Corporation
("Mitsubishi Chemical"), for the development of a PRIMATIZED anti-B7 antibody.
Under the terms of the collaboration, Mitsubishi may provide up to $12,185,000
in product development milestone payments and support for research and
development. The Company retained certain marketing rights and will receive
royalties on sales of any products commercialized by Mitsubishi Chemical
emerging from the collaboration. Mitsubishi Chemical may terminate the license
agreement if certain development objectives are not attained. The development
agreement with Mitsubishi expired on December 31, 1996. Included in contract
revenues for 1995 and 1996 is $2,047,000, and $2,000,000, respectively, to fund
product development, which approximates the research and development expenses
incurred under the program. Included in license fees for the year ended December
31, 1995 is $1,000,000 earned under these agreements.

In October 1992, the Company and SmithKline Beecham p.1.c. ("SmithKline
Beecham") entered into a collaborative research and license agreement aimed at
the development and commercialization of therapeutic products based on the
Company's PRIMATIZED anti-CD4 antibodies. Under the terms of the agreement, the
Company will receive aggregate payments that have the potential of reaching in
excess of $60,000,000, subject to the attainment of certain product development
milestone events. The Company will receive funding for anti-CD4 related research
and development programs, royalties and a share of co-promotion profits (in
North America) on sales of products which may be commercialized as a result of
the agreement. SmithKline Beecham may terminate this agreement based on a
reasonable determination that the products do not justify continued development
or marketing. Included in contract revenues for 1995, 1996 and 1997 is
$3,488,000, $416,000 and $867,000 to fund product development, which
approximates the research and development expenses incurred under the program.
Included in license fees for the year ended December 31, 1996 is $4,000,000
earned under the agreement.

F-11
<PAGE> 70

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

The Company performed research under certain other contracts and,
accordingly, realized revenues and recognized expenses in the accompanying
consolidated statements of operations.

NOTE 7: RELATED PARTY ARRANGEMENTS

In March 1995, the Company and Genentech entered into a collaborative
agreement for the clinical development and commercialization of the Company's
anti-CD20 monoclonal antibody, Rituxan, for the treatment of non-Hodgkin's
B-cell lymphomas. Concurrent with the collaborative agreement the Company and
Genentech also entered into an expression technology license agreement for a
proprietary gene expression technology developed by the Company and a preferred
stock purchase agreement providing for certain equity investments in the Company
by Genentech (Note 8). Under the terms of these agreements, the Company may
receive payments totaling $58,500,000, subject to the attainment of certain
product development milestone events. Additionally, the Company may be
reimbursed by Genentech for certain other development and regulatory approval
expenses under the terms of the collaborative agreement. Genentech may terminate
this agreement for any reason. Included in contract revenues for 1995, 1996 and
1997 is $1,083,000, $1,500,000 and $2,389,000, respectively, to fund specific
product development, which approximates the research and development expenses
incurred under the program. Included in license fees for the years ended
December 31, 1995, 1996 and 1997, is $5,500,000, $4,000,000 and $15,000,000,
respectively, earned under these agreements.

In addition, the Company and Genentech are co-promoting Rituxan in the
United States under a joint business arrangement, with the Company receiving a
share of the pretax operating results. During 1997, the joint business recorded
an operating loss due to significant shared expenses related to the product
launch of Rituxan in the United States in December 1997. Additionally, the
Company has a contractual obligation to manufacture and supply Rituxan through
the end of 1999 with an option to continue supplying Rituxan thereafter. Under
the Company's collaborative agreement with Genentech, the sales price of bulk
Rituxan sold to Genentech is capped at a price which is currently less than the
Company's cost to manufacture bulk Rituxan. Included in inventories at December
31, 1997, is $2,444,000 of bulk Rituxan inventory that will be sold to
Genentech. Revenues from unconsolidated joint business, as described in Note 1,
for the year ended December 31, 1997, consist of the following (table in
thousands):

<TABLE>
<S> <C>
Bulk Rituxan sales......................................... $10,631
Reimbursement of selling and development expenses.......... 2,985
Co-promotion operating loss................................ (4,350)
-------
$ 9,266
=======
</TABLE>

Under the terms of separate agreements with Genentech, commercialization of
Rituxan outside the United States will be the responsibility of Hoffmann-La
Roche, except in Japan where Zenyaku will be responsible for product
development, marketing and sales. The Company will receive royalties on sales
outside the U.S. and Canada. Additionally, the Company will receive royalties on
sales of Genentech products manufactured using the Company's proprietary gene
expression system.

In June 1991, the Company and Zenyaku entered into a product rights
agreement and a stock purchase agreement under which the Company granted Zenyaku
a license to manufacture, use and sell certain products for cancer and
autoimmune therapeutic applications. In November 1995, the Company and Zenyaku
terminated the product rights agreement and concurrently the Company, Zenyaku
and Genentech entered into a joint development, supply and license agreement
where Zenyaku received exclusive rights to develop, market and sell Rituxan in
Japan which resulted in the Company recognizing $2,000,000 in license fees from
Zenyaku in 1995.

F-12
<PAGE> 71

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

NOTE 8: STOCKHOLDERS' EQUITY

Convertible Preferred Stock: In March 1995, the Company issued 1,000,000
shares of its common stock and 69,375 shares of its ten percent Series B
Nonvoting Cumulative Convertible Preferred Stock ("Series B Preferred Stock")
for the repurchase of all Merrill Lynch/Morgan Stanley, L.P. ("ML/MS") rights in
the Company's lymphoma products. The stock issuances resulted in a non-cash
charge to operating expenses in 1995 of $11,437,000, representing the purchase
of the acquired technology rights. In March 1997, the Series B Preferred Stock
and accrued dividends were converted into 367,000 shares of the Company's common
stock.

Additionally, the Company issued 100,000 shares of its Series A-1 Nonvoting
Convertible Preferred Stock ("Series A-1 Preferred Stock") in April 1995, and
37,521 shares of its Series A-2 Nonvoting Convertible Preferred Stock ("Series
A-2 Preferred Stock") in August 1995, 22,993 shares of its Series A-3 Nonvoting
Convertible Preferred Stock ("Series A-3 Preferred Stock") in March 1996,
100,000 shares of its Series A-6 Nonvoting Convertible Preferred Stock ("Series
A-6 Preferred Stock") in May 1996, to Genentech pursuant to the terms of a
preferred stock purchase agreement. The preferred stock purchase agreement was
entered into concurrently with a collaboration agreement as described in Note 7.
The Series A-1 Preferred Stock, Series A-2 Preferred Stock, Series A-3 Preferred
Stock and Series A-6 Preferred Stock have a liquidation preference per share of
$50, $67, $217 and $75, respectively, net of issuance costs. Each share of
Series A-1 Preferred Stock, Series A-2 Preferred Stock and Series A-3 Preferred
Stock is convertible at any time into ten shares of the Company's common stock
and each share of Series A-6 Preferred Stock is convertible at any time into
approximately 2.16 shares of the Company's common stock. In December 1997,
16,000 shares of Series A-1 Preferred Stock were converted into 155,000 shares
of the Company's common stock.

Common Stock: In May 1996, the stockholders approved an increase in the
number of authorized common shares to 50,000,000 shares. In June 1996, the
Company completed a public offering of 2,070,000 shares of its common stock
resulting in net proceeds of $46,277,000. In March 1995, the Company issued
1,000,000 shares of its common stock for the repurchase of all ML/MS rights in
the Company's lymphoma products, see "Convertible Preferred Stock" above.

In September 1997, the Company entered into an agreement with a financial
institution under which the Company purchased in a private transaction a capped
call option, exercisable only at maturity, representing the Company's right to
purchase from the financial institution up to 600,000 shares of the Company's
common stock. The Company has the right to settle the capped call option by
receiving cash or stock. The capped call option which the Company purchased is
expected to be settled, if exercised, with cash paid to the Company in an amount
equal to the difference between the strike price and the market price, subject
to caps which will limit the total amount of cash the Company could receive.

Simultaneously, with its purchase of the capped call option, the Company
sold to the same financial institution a call option, exercisable only at
maturity, entitling the financial institution to purchase from the Company up to
900,000 shares of the Company's common stock at a certain strike price per
share. The Company has the right to settle the call option with cash or stock
and, if exercised, the Company expects to settle the call option by issuing up
to 900,000 shares of the Company's common stock to the financial institution.
The financial institution has advised the Company that it has engaged, and may
further engage, in transactions, including buying and selling shares of the
Company's common stock, to offset its risk relating to the call option, which
could affect the market price of the Company's common stock.

Stockholder Rights Agreement: In July 1997, the Company's Board of
Directors declared a dividend of one preferred stock purchase right ("Right")
for each outstanding share of the Company's common stock. Each Right represents
the right to purchase one one-thousandth of a share of Series X Junior
Participating Preferred Stock at an exercise price of $200, subject to
adjustment, and will be exercisable only if a person or group acquires 15% or
more of the Company's common stock or announces a tender offer for 15% or more
of the Company's common stock. If a person acquires 15% or more of Company's
common stock all

F-13
<PAGE> 72

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

Rightsholders, except the acquiring person, will be entitled to buy shares of
the Company's common stock at a discount. Each Series X Junior Participating
Preferred share will be entitled to an aggregate dividend of 1,000 times the
dividend declared per share of common stock. The Board of Directors may
terminate the Rights Plan at any time or redeem the Rights at $.001 per Right,
prior to the time a person acquires more than 15% of the Company's common stock.
The Rights will expire in July 2007.

Stock Option Plans: The Company has two active stock option plans.

The 1988 Employee Stock Option Plan (the "Option Plan") was approved by the
stockholders in 1988 and has been subsequently amended. Under the Option Plan,
options for the purchase of the Company's common stock may be granted to key
employees (including officers), directors and outside consultants. Options may
be designated as incentive stock options or as nonqualified stock options and
generally vest over four years, except under a provision of the Option Plan
which allows accelerated vesting under certain conditions. Options under the
Option Plan, which have a term of up to ten years, are exercisable at a price
per share not less than the fair market value (85 percent of fair market value
for nonqualified options) on the date of grant. The aggregate number of shares
authorized for issuance under the Option Plan is 5,480,000.

In September 1993, the Company adopted the 1993 Non-Employee Directors
Stock Option Plan (the "Directors Plan"), which was approved by the stockholders
in May 1994 and was subsequently amended. A total of 250,000 shares of common
stock are reserved for issuance to individuals who serve as non-employee members
of the Board of Directors. Options under the Directors Plan, which have a term
of up to ten years, are exercisable at a price per share not less than the fair
market value on the date or grant.

A summary of the status of the Company's two active stock option plans as
of December 31, 1995, 1996 and 1997 and changes during the years ended on those
dates is presented below (table in thousands, except per share amounts):

<TABLE>
<CAPTION>
DIRECTORS PLAN OPTION PLAN
--------------------------- ---------------------------
WEIGHTED AVERAGE WEIGHTED AVERAGE
SHARES EXERCISE PRICE SHARES EXERCISE PRICE
------ ---------------- ------ ----------------
<S> <C> <C> <C> <C>
Outstanding at December 31, 1994... 35 $ 5.63 2,346 $ 2.96
Granted.......................... 70 3.38 311 3.90
Exercised........................ (10) 5.63 (157) 4.07
Canceled......................... (10) 2.38 (33) 5.58
------ ----- ------
Outstanding at December 31, 1995... 85 4.15 2,467 2.97
Granted.......................... 35 19.13 1,443 20.79
Exercised........................ (10) 4.00 (172) 2.43
Canceled......................... (5) 19.13 (196) 10.10
------ ----- ------
Outstanding at December 31, 1996... 105 8.45 3,542 9.86
Granted.......................... 83 27.41 815 26.27
Exercised........................ (15) 9.04 (533) 4.26
Canceled......................... (5) 22.50 (43) 18.74
------ ----- ------
Outstanding at December 31, 1997... 168 $17.31 3,781 $14.09
====== ===== ======
</TABLE>

F-14
<PAGE> 73

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

The following table summarizes information about the Directors Plan and the
Option Plan options outstanding as of December 31, 1997 (table in thousands,
except year and per share amounts):

<TABLE>
<CAPTION>
OPTIONS OUTSTANDING
----------------------------------------------------- OPTIONS EXERCISABLE
WEIGHTED AVERAGE --------------------------------
RANGE OF NUMBER REMAINING WEIGHTED AVERAGE NUMBER WEIGHTED AVERAGE
EXERCISE PRICES OUTSTANDING CONTRACTUAL LIFE EXERCISE PRICE EXERCISABLE EXERCISE PRICE
- ---------------- ----------- ---------------- ---------------- ----------- ----------------
<S> <C> <C> <C> <C> <C>
Directors Plan:
$ 2.38 -- $19.13 90,000 7.26 $ 8.35 90,000 $ 8.35
22.50 -- 38.25 77,500 9.32 27.72 77,500 27.72

Option Plan:
$ 0.88 -- $ 2.56 663,917 5.55 $ 2.35 567,494 $ 2.32
3.00 -- 3.00 699,116 6.70 3.00 647,081 3.00
3.25 -- 18.00 488,291 7.35 8.87 226,785 6.30
20.13 -- 20.50 953,904 8.10 20.14 432,327 20.13
21.00 -- 37.88 975,373 9.21 26.73 86,870 25.55
</TABLE>

Employee Stock Purchase Plan: In May 1993, the stockholders adopted the
Company's Employee Stock Purchase Plan (the "Purchase Plan"), which was
subsequently amended. A total of 495,000 shares of common stock are reserved for
issuance. Under the terms of the Purchase Plan, employees can choose to have up
to ten percent of their annual compensation withheld to purchase shares of
common stock. The purchase price of the common stock is at 85 percent of the
lower of the fair market value of the common stock at the enrollment or purchase
date. During 1995, 1996 and 1997, 63,000 shares, 160,000 shares and 122,000
shares, respectively, were issued under the Purchase Plan.

Pro Forma Information: The Company has retained the approach under APB
Opinion No. 25 and related interpretations in accounting for its stock option
and purchase plans. Accordingly, no compensation expense has been recognized for
its Option Plan, Directors Plan and Purchase Plan. Had compensation expense for
the Company's stock option and purchase plans been determined consistent with
Statement No. 123, the Company's net loss per share applicable to common stock
would have been increased to the pro forma amounts indicated below (table in
thousands, except per share amounts):

<TABLE>
<CAPTION>
1995 1996 1997
-------- -------- --------
<S> <C> <C> <C> <C>
Net loss applicable to common stock.......... As reported $(17,292) $ (5,651) $(15,538)
Pro forma (17,608) (10,152) (23,746)
Net loss per common share.................... As reported $ (1.18) $ (0.34) $ (0.83)
Pro forma (1.20) (0.61) (1.27)
</TABLE>

Pro forma net loss applicable to common stock reflects only stock option
and purchase rights granted in 1995, 1996 and 1997. Therefore, the full impact
of calculating compensation expense for stock options and stock purchase rights
under Statement No. 123 is not reflected in the pro forma net loss amounts
presented above since compensation expense is reflected over the stock option
vesting and stock purchase subscription periods and compensation expense for
stock options and stock purchase rights granted prior to January 1, 1995 are not
considered. The fair value of each option grant is estimated on the date of
grant using the Black-Scholes option-pricing model with the following
weighted-average assumptions used for grants in 1997, 1996 and 1995: dividend
yield of zero percent; expected volatility of 61.4 percent; risk-free interest
rate of 6.3 percent; and an expected option life of 5.7 years for 1997; and a
dividend yield of zero percent; expected volatility of 66.8 percent; risk-free
interest rate of 6.2 percent; and an expected option life of 5.5 years for 1996
and 1995. The per share weighted-average fair value of stock options granted
during 1995, 1996 and 1997 at an exercise price equal to the fair market value
on the date of grant was $2.42, $13.25 and $16.09, respectively, on the date of
grant using the Black-Scholes option-pricing model. The fair value of each
purchase right is

F-15
<PAGE> 74

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

estimated on the date of enrollment using the Black-Scholes option-pricing model
with the following assumptions used in 1997, 1996 and 1995: dividend yield of
zero percent; expected volatility of 61.4 percent; risk-free interest rates
between 5.5 percent and 6.0 percent; and an expected life between 0.3 year and
2.0 years for 1997; and a dividend yield of zero percent; expected volatility of
66.8 percent; risk-free interest rates between 5.6 percent and 5.9 percent; and
an expected life between 0.3 year and 2.0 years for 1996 and 1995. The per share
weighted-average fair value of stock purchase rights granted during 1995, 1996
and 1997 was $2.65, $9.05 and $10.50, respectively, on the subscription date
using the Black-Scholes option-pricing model.

Stock Warrants: Under an investment agreement and in part subject to the
Company's accomplishments of certain research and development objectives, SR One
Limited, SmithKline Beecham's venture capital subsidiary, purchased 200,000
common stock warrants in each 1993 and 1992. In October 1996, these warrants
were exercised for 400,000 shares of the Company's common stock resulting in net
proceeds of $4,755,000.

In December 1994 and August 1995, concurrent with the completion of a debt
financing, the Company issued warrants for the purchase of 294,000 shares and
46,000 shares, respectively, of common stock. The holders of the warrants have
the option to exchange their warrants, without the payment of cash or
consideration, for a number of common shares equal to the difference between the
number of shares resulting by dividing the aggregate exercise price of the
warrants by the fair market value of the common stock on the date of exercise
and the number of shares that would have been otherwise issued under the
exercise. In 1996 and 1997, 196,000 warrants and 114,000 warrants, respectively,
were exchanged for 169,000 shares and 105,000 shares, respectively, of the
Company's common stock. At December 31, 1997, 30,000 warrants to purchase common
stock were outstanding. Such warrants have a six-year term and are immediately
exercisable at $6.22 per share.

NOTE 9: INCOME TAXES

The following table summarizes the tax effects of temporary differences
that give rise to significant portions of the deferred tax assets and
liabilities at December 31, 1996 and 1997 (table in thousands):

<TABLE>
<CAPTION>
1996 1997
-------- --------
<S> <C> <C>
Deferred tax assets:
Accrued expenses............................................. $ 531 $ 609
Property and equipment, principally due to difference in
depreciation.............................................. 448 1,194
Deferred rent expense........................................ 607 803
Amortization of fair value change in common stock warrants... 776 770
Deferred revenue............................................. -- 2,372
Capitalized state research and experimentation costs......... 2,090 2,189
Acquired technology rights................................... 4,336 3,695
Research and experimentation credit.......................... 5,078 6,070
Net operating loss carryforwards............................. 24,247 29,601
Other tax assets............................................. 333 696
-------- --------
Total gross deferred tax assets...................... 38,446 47,999
Valuation allowance............................................ (38,446) (47,737)
Deferred tax liabilities....................................... -- (262)
-------- --------
Net deferred taxes............................................. $ -- $ --
======== ========
</TABLE>

In 1995, 1996 and 1997, the Company recognized an increase in the valuation
allowance of $7,652,000, $3,882,000 and $9,291,000, respectively.

F-16
<PAGE> 75

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

As of December 31, 1997, the Company had net operating loss and research
and experimentation tax credit carryforwards for Federal income tax purposes of
approximately $82,000,000 and $4,000,000, respectively, which expire beginning
in 1999. Net operating loss carryforwards and research and experimentation tax
credit carryforwards as of December 31, 1997 for state income tax purposes are
approximately $21,000,000 and $2,000,000, respectively, which expire beginning
in 1998 and 1999, respectively.

The utilization of net operating losses and tax credits incurred prior to
the Company's initial public offering in 1991, may be subject to an annual
limitation under the Internal Revenue Code, due to a cumulative change in
ownership of more than fifty percent. However, the Company believes that such
limitations will not have a material impact upon the utilization of such net
operating loss carryforwards.

NOTE 10: COMMITMENTS

Lease Commitments: In July 1992, the Company entered into a 15-year
operating lease for its headquarters, which commenced in 1993. The Company has
the option to extend the term of the lease for two additional periods of five
years each. In August 1996, the Company entered into a 7-year lease for
additional office and warehouse facilities. The Company has the option to extend
the term of this lease for two additional years. In addition to the monthly
lease payments, both lease agreements provide for the Company to pay all
operating expenses associated with the facilities. The lease agreements provide
for scheduled rental increases; accordingly lease expense is recognized on a
straight-line basis over the term of the leases.

Future minimum lease payments under all operating leases as of December 31,
1997, are as follows (table in thousands):

<TABLE>
<S> <C>
1998....................................................... $ 3,158
1999....................................................... 3,422
2000....................................................... 3,559
2001....................................................... 3,702
2002....................................................... 3,850
2003 and thereafter........................................ 18,445
-------
Total minimum lease payments..................... $36,136
=======
</TABLE>

Lease expense under all operating leases totaled $3,097,000, $3,011,000 and
$3,677,000 for the years ended December 31, 1995, 1996 and 1997, respectively.

License Agreements: In September 1997, the Company and Cytokine Networks,
Inc. ("CNI") entered into a development and license agreement for the
development of inflammatory and autoimmune disease products based upon CNI's
Anti-MIF antibody technology. Concurrent with the development and license
agreement the Company and CNI entered into a stock purchase agreement providing
for certain equity investments in CNI by the Company. Under the terms of these
agreements, the Company may make payments totaling up to $10,500,000, subject to
the attainment of certain product development milestone events. Additionally,
the Company will pay CNI royalties on sales by the Company of any products
emerging from the collaboration. In 1997, the Company made a $3,000,000
preferred equity investment in CNI.

In February 1997, the Company acquired exclusive rights from Pharmacia &
Upjohn S.p.A. ("Pharmacia") to 9-aminocamptothecin ("9-AC"), a broad spectrum,
anti-cancer agent for the treatment of cancer. Under the terms of the asset
transfer agreement, the Company may make payments totaling up to $16,000,000,
subject to the attainment of certain product development milestone events. No
royalties are payable to Pharmacia on sales of any products commercialized by
the Company emerging from the agreement. In 1997, the Company made an up-front
licensing payment of $3,000,000 to Pharmacia.

F-17
<PAGE> 76

IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

In connection with its research and development efforts, the Company has
entered into various license agreements which provide the Company with rights to
develop, produce and market products using certain know-how, technology and
patent rights maintained by the parties. Terms of the various license agreements
require the Company to pay royalties from future sales, if any, on specified
products using the resulting technology. Third party royalty liabilities
resulting from sales of Rituxan are being paid by Genentech and recorded under
the joint business arrangement as described under "Revenues from Unconsolidated
Joint Business" in Notes 1 and 7. As of December 31, 1997, such other royalties,
other than annual minimum royalties payments, have not commenced on the
aforementioned license agreements.

F-18
<PAGE> 77

LOGO
<PAGE> 78

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

ITEM 14. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION.

The following table sets forth all expenses, other than underwriting
discounts and commissions, payable by the Registrant in connection with the sale
of the Common Stock being registered. All the amounts shown are estimates,
except for the SEC registration fee, the Nasdaq listing fee and the NASD filing
fee.

<TABLE>
<S> <C>
SEC registration fee...................................................... $ 30,711
Listing fee............................................................... 17,500
NASD filing fee........................................................... 1,513
Blue sky fees and expenses................................................ 10,000
Printing and engraving expenses........................................... 60,000
Legal fees and expenses................................................... 100,000
Accounting fees and expenses.............................................. 50,000
Transfer agent and registrar fees......................................... 2,500
Miscellaneous expenses.................................................... 2,776
--------
Total........................................................... $275,000
========
</TABLE>

ITEM 15. INDEMNIFICATION OF OFFICERS AND DIRECTORS.

Section 145 of the Delaware General Corporation Law, as amended (the
"DGCL"), provides that a corporation may indemnify any person who was or is a
party or is threatened to be made a party to any threatened, pending or
completed action, suit or proceeding, whether civil, criminal or investigative
(other than an action by or in the right of the corporation) by reason of the
fact that he is or was a director, officer, employee or agent of the
corporation, or is or was serving at the request of the corporation as a
director, officer, employee or agent of another corporation, partnership, joint
venture, trust or other enterprise, against expenses (including attorneys'
fees), judgments, fines and amounts paid in settlement actually and reasonably
incurred by him in connection with such action, suit or proceeding, if he acted
in good faith and in a manner he reasonably believed to be in or not opposed to
the best interests of the corporation, and, with respect to any criminal action
or proceeding, had no reasonable cause to believe his conduct was unlawful.
Section 145 further provides that a corporation similarly may indemnify any such
person serving in any such capacity who was or is a party or is threatened to be
made a party to any threatened, pending or completed action or suit by or in the
right of the corporation to procure a judgment in its favor, against expenses
actually and reasonably incurred in connection with the defense or settlement of
such action or suit if he acted in good faith and in a manner he reasonably
believed to be in or not opposed to the best interests of the corporation and
except that no indemnification shall be made in respect of any claim, issue or
matter as to which such person shall have been adjudged to be liable to the
corporation unless and only to the extent that the Delaware Court of Chancery or
such other court in which such action or suit was brought shall determine upon
application that, despite the adjudication of liability but in view of all the
circumstances of the case, such person is fairly and reasonably entitled to
indemnity for such expenses which the Court of Chancery or such other court
shall deem proper.

Section 102(b)(7) of the DGCL permits a corporation to include in its
certificate of incorporation a provision eliminating or limiting the personal
liability of a director to the corporation or its stockholders for monetary
damages for breach of fiduciary duty as a director, provided that such provision
shall not eliminate or limit the liability of a director (i) for any breach of
the director's duty of loyalty to the corporation or its stockholders, (ii) for
acts or omissions not in good faith or which involve intentional misconduct or a
knowing violation of law, (iii) under Section 174 of the DGCL (relating to
unlawful payment of dividends and unlawful stock purchase and redemption) or
(iv) for any transaction from which the director derived an improper personal
benefit.

II-1
<PAGE> 79

The Registrant's Certificate of Incorporation provides that the
Registrant's directors shall not be liable to the Registrant or its stockholders
for monetary damages for breach of fiduciary duty as a director, except to the
extent that exculpation from liabilities is not permitted under the DGCL as in
effect at the time such liability is determined. The Registrant has entered into
indemnification agreements with all of its officers and directors, as permitted
by the DGCL. Reference is also made to Section
- ------ of the Underwriting Agreement contained in Exhibit 1.1 hereto,
indemnifying officers and directors of the Registrant against certain
liabilities.

ITEM 16. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES.

Exhibits.

<TABLE>
<CAPTION>
EXHIBIT
NUMBER
- ------
<C> <S>
1.1 Form of Underwriting Agreement.
5.1 Opinion of Brobeck, Phleger & Harrison LLP.
23.1 Consent of Brobeck, Phleger & Harrison LLP (included in Exhibit 5.1).
23.2 Consent of KPMG Peat Marwick LLP.
24.1 Power of Attorney (included in Page II-4 of this Registration Statement).
27.1 Financial Data Schedule.
</TABLE>

ITEM 17. UNDERTAKINGS.

The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange Act of 1934 (and, where applicable, each filing of an
employee benefit plan's annual report pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
Registration Statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

The undersigned Registrant hereby undertakes to deliver or cause to be
delivered with the Prospectus, to each person to whom the Prospectus is sent or
given, the latest annual report to security holders that is incorporated by
reference in the Prospectus and furnished pursuant to and meeting the
requirements of Rule 14a-3 or Rule 14c-3 under the Securities Exchange Act of
1934; and, where interim financial information required to be presented by
Article 3 of Regulation S-X is not set forth in the Prospectus, to deliver, or
cause to be delivered to each person to whom the Prospectus is sent or given,
the latest quarterly report that is specifically incorporated by reference in
the Prospectus to provide such interim financial information.

Insofar as indemnification for liabilities arising under the Securities Act
of 1933 may be permitted to directors, officers and controlling persons of the
Company pursuant to the provisions described in Item 15, or otherwise, the
Company has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the Act
and is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Company of expenses
incurred or paid by a director, officer or controlling person of the Company in
the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Company will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Act and will be governed by the final adjudication of
such issue.

The undersigned registrant hereby undertakes that:

(1) For purposes of determining any liability under the Securities Act
of 1933, the information omitted from the form of prospectus filed as part
of this registration statement in reliance upon

II-2
<PAGE> 80

Rule 430A and contained in a form of prospectus filed by the registrant
pursuant to Rule 424(b)(1) or (4) or 497(h) under the Securities Act shall
be deemed to be part of this registration statement as of the time it was
declared effective.

(2) For the purpose of determining any liability under the Securities
Act of 1933, each post-effective amendment that contains a form of
prospectus shall be deemed to be a new registration statement relating to
the securities offered therein, and the offering of such securities at that
time shall be deemed to be the initial bona fide offering thereof.

II-3
<PAGE> 81

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the
Company certifies that it has reasonable grounds to believe that it meets all of
the requirements for filing on Form S-3 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of San Diego, State of California, on the day of
February, 1998.

IDEC PHARMACEUTICALS CORPORATION

By: /s/ WILLIAM H. RASTETTER

--------------------------------
William H. Rastetter, Ph.D.
Chairman, President and Chief
Executive Officer

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears
below does hereby constitute and appoint William H. Rastetter and Phillip M.
Schneider, or either of them, as his true and lawful attorneys-in-fact and
agents, with full power of substitution, for him and his name, place and stead,
in any and all capacities, to sign the Registration Statement filed herewith and
any and all amendments to said Registration Statement (including post-effective
amendments and registration statements filed pursuant to Rule 462 and
otherwise), and to file the same, with all exhibits thereto, and other documents
in connection therewith, with the Securities and Exchange Commission, granting
unto said attorneys-in-fact and agents, full power and authority to do and
perform each and every act and thing requisite and necessary to be done in
connection therewith as fully to all intents and purposes as he might or could
do in person, hereby ratifying and confirming that all said attorneys-in-fact
and agents, or their substitute or substitutes may lawfully do or cause to be
done by virtue hereof.

IN WITNESS WHEREOF, each of the undersigned has executed this Power of
Attorney as of the date indicated.

Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities and on the dates indicated.

<TABLE>
<CAPTION>
SIGNATURE TITLE DATE
- -------------------------------------- --------------------------------------- ------------------
<S> <C> <C>

/s/ WILLIAM H. RASTETTER Chairman, President, and Chief February 20, 1998
- -------------------------------------- Executive Officer (Principal Executive
William H. Rastetter, Ph.D. Officer)
/s/ PHILLIP M. SCHNEIDER Vice President, and Chief Financial February 20, 1998
- -------------------------------------- Officer (Principal Financial and
Phillip M. Schneider Accounting Officer)

/s/ CHARLES C. EDWARDS Director February 20, 1998
- --------------------------------------
Charles C. Edwards, M.D.

/s/ ALAN B. GLASSBERG Director February 20, 1998
- --------------------------------------
Alan B. Glassberg, M.D.

/s/ JOHN GROOM Director February 20, 1998
- --------------------------------------
John Groom

/s/ KAZUHIRO HASHIMOTO Director February 20, 1998
- --------------------------------------
Kazuhiro Hashimoto
</TABLE>

II-4
<PAGE> 82

<TABLE>
<CAPTION>
SIGNATURE TITLE DATE
- -------------------------------------- --------------------------------------- ------------------
<S> <C> <C>

/s/ FRANKLIN P. JOHNSON, JR. Director February 20, 1998
- --------------------------------------
Franklin P. Johnson, Jr.

/s/ ROBERT W. PANGIA Director February 20, 1998
- --------------------------------------
Robert W. Pangia

/s/ BRUCE R. ROSS Director February 20, 1998
- --------------------------------------
Bruce R. Ross

/s/ THE HONORABLE LYNN SCHENK Director February 20, 1998
- --------------------------------------
The Honorable Lynn Schenk

/s/ WILLIAM D. YOUNG Director February 20, 1998
- --------------------------------------
William D. Young
</TABLE>

II-5
<PAGE> 83

EXHIBIT INDEX

<TABLE>
<CAPTION>
SEQUENTIALLY
EXHIBIT NUMBERED
NUMBER DESCRIPTION PAGE
- ------ ------------------------------------------------------------------------- ------------
<C> <S> <C>
1.1 Form of Underwriting Agreement.
5.1 Opinion of Brobeck, Phleger & Harrison LLP.
23.1 Consent of Brobeck, Phleger & Harrison LLP (included in Exhibit 5.1).
23.2 Consent of KPMG Peat Marwick LLP.
24.1 Power of Attorney (included in Page II-4 of this Registration Statement).
27.1 Financial Data Schedule.
</TABLE>

<PAGE> 1
2,000,000 SHARES

IDEC PHARMACEUTICALS CORPORATION

COMMON STOCK, $.001 PAR VALUE

UNDERWRITING AGREEMENT

<PAGE> 2
March __, 1998

Morgan Stanley & Co. Incorporated
Nationsbanc Montgomery Securities, Inc.
c/o Morgan Stanley & Co. Incorporated
1585 Broadway
New York, New York 10036

Dear Sirs and Mesdames:

IDEC Pharmaceuticals Corporation, a Delaware corporation (the "Company"),
proposes to issue and sell to the several Underwriters named in Schedule I
hereto (the "Underwriters"), an aggregate of 2,000,000 shares of the Common
Stock, $.001 par value per share of the Company (the "Firm Shares").

The Company also proposes to issue and sell to the several Underwriters not
more than an additional 300,000 shares of its Common Stock, $.001 par value (the
"Additional Shares") if and to the extent that you, as Managers of the offering,
shall have determined to exercise, on behalf of the Underwriters, the right to
purchase such shares of common stock granted to the Underwriters in Section 2
hereof. The Firm Shares and the Additional Shares are hereinafter collectively
referred to as the "Shares." The shares of Common Stock, $.001 par value, of the
Company to be outstanding after giving effect to the sales contemplated hereby
are hereinafter referred to as the "Common Stock." The Company is successor by
merger to IDEC Pharmaceuticals Corporation, a California corporation (the
"Predecessor"), as a result of a reincorporation transaction that became
effective on June 2, 1997 (the "Reincorporation"). For the purposes of Section 1
hereof, all references to "Company" shall also refer to the Predecessor prior to
the Reincorporation.

The Company has filed with the Securities and Exchange Commission (the
"Commission") a registration statement, including a prospectus, relating to the
Shares. The registration statement as amended at the time it becomes effective,
including the information (if any) deemed to be part of the registration
statement at the time of effectiveness pursuant to Rule 430A under the
Securities Act of 1933, as amended (the "Securities Act"), is hereinafter
referred to as the "Registration Statement"; the prospectus in the form first
used to confirm sales of Shares is hereinafter referred to as the "Prospectus."
If the Company files an abbreviated registration statement to register
additional shares of Common Stock pursuant to Rule 462(b) under the Securities
Act (the "Rule 462 Registration Statement"), then any reference herein to the
term "Registration Statement" shall be deemed to include such Rule 462
Registration Statement, in each case as amended from time to time. Any reference
herein to any Preliminary Prospectus or the Registration Statement shall be
deemed to refer to and include the documents incorporated by reference therein
pursuant to Form S-3 under the Securities Act, as of the date of such
Preliminary Prospectus, Prospectus or Registration Statement, as the case may
be.

1. REPRESENTATIONS AND WARRANTIES OF THE COMPANY. The Company represents
and warrants to and agrees with each of the Underwriters that:

<PAGE> 3
(a) The Registration Statement has become effective; no stop order
suspending the effectiveness of the Registration Statement is in effect, and no
proceedings for such purpose are pending before or, to the Company's best
knowledge, threatened by the Commission.

(b) (i) The Registration Statement, when it became effective, did not
contain and, as amended or supplemented, if applicable, will not contain any
untrue statement of a material fact or omit to state a material fact required to
be stated therein or necessary to make the statements therein not misleading,
(ii) the Registration Statement and the Prospectus comply and, as amended or
supplemented, if applicable, will comply in all material respects with the
Securities Act and the applicable rules and regulations of the Commission
thereunder and (iii) the Prospectus does not contain and, as amended or
supplemented, if applicable, will not contain any untrue statement of a material
fact or omit to state a material fact necessary to make the statements therein,
in the light of the circumstances under which they were made, not misleading,
except that the representations and warranties set forth in this Section l(b) do
not apply to statements or omissions in the Registration Statement or the
Prospectus based upon information relating to any Underwriter furnished to the
Company in writing by such Underwriter through you expressly for use therein.

(c) The Company has been duly incorporated, is validly existing as a
corporation in good standing under the laws of the jurisdiction of its
incorporation, has the corporate power and authority to own its property and to
conduct its business as described in the Prospectus and, except to the extent
that the failure to be so qualified or to be in good standing would not have a
material adverse effect on the Company and its subsidiary, IDEC Seiyaku, a
Japanese corporation (the "Subsidiary"), taken as a whole is duly qualified to
transact business and is in good standing in each jurisdiction in which the
conduct of its business or its ownership or leasing of property requires such
qualification.

(d) The Subsidiary has been duly incorporated, is validly existing as
a corporation in good standing under the laws of the jurisdiction of its
incorporation, has the corporate power and authority to own its property and to
conduct its business as described in the Prospectus and is duly qualified to
transact business and is in good standing in each jurisdiction in which the
conduct of its business or its ownership or leasing of property requires such
qualification, except to the extent that the failure to be so qualified or to be
in good standing would not have a material adverse effect on the Company and the
Subsidiary, taken as a whole. All of the issued shares of capital stock of the
Subsidiary have been duly and validly authorized and issued, are fully paid and
non-assessable, and are beneficially owned directly by the Company, free and
clear of all liens, encumbrances, equities or claims.

(e) Neither the Company nor the Subsidiary owns any real properties.
The Company and the Subsidiary have good and marketable title to all personal
property owned by them which is material to their business, taken as a whole, in
each case free and clear of all liens, encumbrances and defects except such as
are described in the Prospectus or such as do not materially affect the value of
such property and do not interfere with the use made and proposed to be made of
such property by the Company and the Subsidiary; and any real property and

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<PAGE> 4
building held under lease by the Company and the Subsidiary are held by them
under valid, subsisting and enforceable leases with such exceptions as are not
material and do not interfere with the use made and proposed to be made of such
real property and buildings by the Company and the Subsidiary in each case
except as described in or contemplated by the Prospectus.

(f) This Agreement has been duly authorized, executed and delivered by
the Company.

(g) The shares of Common Stock outstanding prior to the issuances of
the Shares to be sold by the Company have been duly authorized and are validly
issued, fully paid and non-assessable. Except as set forth in the Prospectus and
other than options to purchase __________ shares of the Company's Common Stock
granted to employees after _______ __, 199_ pursuant to the Company's 1988
Employee Stock Option Plan or the 1993 Non-Employee Directors Stock Option Plan
each as described in the Prospectus, neither the Company nor the Subsidiary has
outstanding any options to purchase, or any preemptive rights or other rights to
subscribe for or to purchase, any securities or obligations convertible into, or
any contracts or commitments to issue or sell, shares of its capital stock or
any such options, rights, convertible securities or obligations. All outstanding
shares of capital stock and options and other rights to acquire capital stock
have been issued in compliance with the registration and qualification
provisions of all applicable securities laws and were not issued in violation of
any preemptive rights, rights of first refusal and other similar rights.

(h) The authorized capital stock of the Company conforms as to legal
matters to the description thereof contained in the Prospectus.

(i) The Shares to be sold by the Company have been duly authorized
and, when issued and delivered in accordance with the terms of this Agreement,
will be validly issued, fully paid and non-assessable, and the issuance of such
Shares will not be subject to any preemptive or similar rights.

(j) The execution and delivery by the Company of, and the performance
by the Company of its obligations under, this Agreement will not contravene any
provision of applicable law or the certificate of incorporation or by-laws of
the Company or any agreement or other instrument binding upon the Company or the
Subsidiary that is material to the Company and the Subsidiary, taken as a whole,
or any judgment, order or decree of any governmental body, agency or court
having jurisdiction over the Company or the Subsidiary, and no consent,
approval, authorization or order of, or qualification with, any governmental
body or agency is required for the performance by the Company of its obligations
under this Agreement, except such as may be required by the securities or Blue
Sky laws of the various states in connection with the offer and sale of the
Shares.

(k) There has not occurred any material adverse change, or any
development involving a prospective material adverse change, in the condition,
financial or otherwise, or in the earnings, business or operations of the
Company and the Subsidiary, taken as a whole, from that set forth in the
Prospectus.

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<PAGE> 5
(l) Subsequent to the respective dates as of which information is
given in the Registration Statement and the Prospectus, (i) the Company and the
Subsidiary have not incurred any material liability or obligation, direct or
contingent, nor entered into any material transaction not in the ordinary course
of business; (ii) the Company has not purchased any of its outstanding capital
stock, nor declared, paid or otherwise made any dividend or distribution of any
kind on its capital stock other than ordinary and customary dividends except
certain net purchases of options issued and shares issued on exercise of options
under the Company's stock option plans in accordance with the terms of such
option plans; and (iii) there has not been any material change in the capital
stock, short-term debt or long-term debt of the Company and its consolidated
subsidiaries, except in each case as described in or contemplated by the
Prospectus.

(m) There are no legal or governmental proceedings pending or
threatened to which the Company or the Subsidiary is a party or to which any of
the properties of the Company or the Subsidiary is subject that are required to
be described in the Registration Statement or the Prospectus and are not so
described or any statutes, regulations, contracts or other documents that are
required to be described in the Registration Statement or the Prospectus or to
be filed as exhibits to the Registration Statement that are not described or
filed as required.

(n) Each preliminary prospectus filed as part of the Registration
Statement as originally filed or as part of any amendment thereto, or filed
pursuant to Rule 424 or Rule 462 under the Securities Act, complied when so
filed in all material respects with the Securities Act and the applicable rules
and regulations of the Commission thereunder.

(o) The Company is not and, after giving effect to the offering and
sale of the Shares and the application of the proceeds thereof as described in
the Prospectus, will not be an "investment company" as such term is defined in
the Investment Company Act of 1940, as amended.

(p) There is no owner of any securities of the Company who has any
right, not effectively satisfied or waived, to require registration of any
shares of capital stock of the Company in connection with the filing of the
Registration Statement or the sale of any shares thereunder.

(q) The Company and the Subsidiary (i) are in compliance with any and
all applicable foreign, federal, state and local laws and regulations relating
to the protection of human health and safety, the environment or hazardous or
toxic substances or wastes, pollutants or contaminants ("Environmental Laws"),
(ii) have received all permits, licenses or other approvals required of them
under applicable Environmental Laws to conduct their respective businesses and
(iii) are in compliance with all terms and conditions of any such permit,
license or approval, except where such noncompliance with Environmental Laws,
failure to receive required permits, licenses or other approvals or failure to
comply with the terms and conditions of such permits, licenses or approvals
would not, singly or in the aggregate, have a material adverse effect on the
Company and the Subsidiary, taken as a whole.

(r) The Company has conducted a limited review of the effect of
Environmental Laws on the business, operations and properties of the Company and
the

4
<PAGE> 6
Subsidiary. On the basis of such review, the Company has reasonably concluded
that any costs and liabilities required for clean-up, closure of properties or
compliance with Environmental Laws would not, singly or in the aggregate, have a
material adverse effect on the Company and the Subsidiary, taken as a whole.

(s) There are no contracts, agreements or understandings between the
Company and any person granting such person the right to require the Company to
file a registration statement under the Securities Act with respect to any
securities of the Company or to require the Company to include such securities
with the Shares registered pursuant to the Registration Statement.

(t) The Company has complied with all provisions of Section 517.075,
Florida Statutes relating to doing business with the Government of Cuba or with
any person or affiliate located in Cuba.

(u) The Company and the Subsidiary are insured by insurers of
recognized financial responsibility against such losses and risks and in such
amounts as are prudent and customary in the businesses in which they are
engaged; neither the Company nor the Subsidiary has been refused any material
insurance coverage sought or applied for; and neither the Company nor the
Subsidiary has any reason to believe that it will not be able to renew its
existing insurance coverage as and when such coverage expires or to obtain
similar coverage from similar insurers as may be necessary to continue its
business at a cost that would not materially and adversely affect the condition,
financial or otherwise, or the earnings, business or operations of the Company
and the Subsidiary, taken as a whole, except as described in or contemplated by
the Prospectus.

(v) Except as specifically disclosed in the Prospectus, (i) the
Company and the Subsidiary own or possess adequate licenses or other rights to
use all patents, copyrights, trademarks, service marks, trade names, technology
and know-how necessary to conduct their respective businesses in the manner
described in the Prospectus, (ii) neither the Company nor the Subsidiary has
received any notice of infringement or conflict with asserted rights of others
with respect to any patents, copyrights, trademarks, service marks, trade names,
technology or know-how that could reasonably be expected to result in any
material adverse effect upon the Company and the Subsidiary, taken as a whole,
and (iii) the discoveries, inventions, products or processes of the Company and
the Subsidiary referred to in the Prospectus do not, to the best knowledge of
the Company, infringe or conflict with any right or patent of any third party,
or any discovery, invention, product or process that could reasonably be
expected to have a material adverse effect on the Company and the Subsidiary,
taken as a whole.

(w) The Company and the Subsidiary possess all consents, approvals,
orders, certificates, authorizations and permits issued by, and has made all
declarations and filings with, all appropriate federal, state or foreign
governmental and self-regulatory authorities and all courts and other tribunals
necessary to conduct their respective businesses and to own, lease, license and
use their properties in the manner described in the Prospectus, except to the
extent that the failure to obtain or file would not have a material adverse
effect on the Company

5
<PAGE> 7
and the Subsidiary, taken as a whole, and neither the Company nor the Subsidiary
has received any notice of proceedings related to the revocation or modification
of any such consent, approval, order, certificate, authorization or permit that,
singly or in the aggregate, could reasonably be expected to result in a material
adverse change in the condition, financial or otherwise, or in the earnings,
business or operations of the Company and the Subsidiary, taken as a whole.

(x) __________ and __________ outstanding shares of the Common Stock
and securities convertible into or exercisable or exchangeable for Common Stock,
respectively, are subject to valid, binding and enforceable agreements
(collectively, the "Lock-Up Agreements") that restrict the holders thereof from
selling, making any short sale of, granting any option for the purchase of, or
otherwise transferring or disposing of, any of such shares of Common Stock, or
any such securities convertible or exercisable or exchangeable for Common Stock,
for a period of 90 days, respectively, after the date of the Prospectus without
the prior written consent of Morgan Stanley.

(y) As of the date the Registration Statement became effective, the
Common Stock was authorized for quotation on The Nasdaq National Market upon
official notice of issuance.

(z) The Company has not taken and will not take, directly or
indirectly, any action designed to cause or result in, or which constitutes or
which might reasonably be expected to constitute, the stabilization or
manipulation of the price of the shares of Common Stock to facilitate the sale
or resale of the Shares.

(aa) The Company does not own any equity or capital interests in any
corporation, partnership, joint venture, association or other entity, other than
the Subsidiary.

(bb) The Agreement and Plan of Merger (the "Plan of Merger") by and
between the Company and the Predecessor has been duly authorized by all
necessary Board of Directors and stockholder action on part of the Company and
the Predecessor and has been duly executed and delivered by each of the parties
thereto.

(cc) The execution and delivery of the Plan of Merger and the
consummation of the merger contemplated thereby do not contravene any provision
of applicable law or the certificate of incorporation or bylaws of the Company
or the articles of incorporation or bylaws of the Predecessor or any judgment or
decree of any governmental body, agency or court having jurisdiction over the
Predecessor or the Subsidiary, and no consent, approval, authorization or order
of or qualification with any governmental body or agency is required for the
performance by the Company and the Predecessor of their respective obligations
under the Plan of Merger except such as have been obtained or are not material
to the Company; the consummation of the Reincorporation does not contravene, or
result in any breach of, or constitute a default under (or constitute any event
which with notice, lapse of time or both would constitute a breach of or default
under), any provision of any agreement or other instrument binding upon the
Company or the Subsidiary and identified by the Company as material (the
"Material Agreements").

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<PAGE> 8
(dd) The merger contemplated by the Plan of Merger is effective under
the laws of the State of California and the State of Delaware; the Company has
succeeded to all of the rights, privileges, powers and franchises, and is
subject to all of the restrictions, disabilities and duties, of the Predecessor
as provided under Section 259 of the Delaware General Corporation Law; to the
knowledge of such counsel, the Company has succeeded to all of the rights of the
Predecessor with respect to each Material Agreement of the Predecessor, and all
required material consents to the merger and assignments with respect to such
Material Agreements have been obtained; all of the shares of capital stock of
the Company have the same rights, preferences and privileges (except for
differences resulting from applicable law) as described in the Prospectus; all
of the outstanding options of the Predecessor outstanding as of the date set
forth in the Prospectus are outstanding for that number of shares of Common
Stock of the Company as described in the Prospectus, other than options which
have terminated or expired by their terms and not as a result of the
Reincorporation; the issuance of capital stock by the Company in the
Reincorporation was in compliance with all applicable registration and
qualification provisions of state securities or blue sky laws as are identified
therein and was exempt from registration under the Securities Act.

2. AGREEMENTS TO SELL AND PURCHASE. The Company hereby agrees to sell to
the several Underwriters, and each Underwriter, upon the basis of the
representations and warranties herein contained, but subject to the conditions
hereinafter stated, agrees, severally and not jointly, to purchase from the
Company at $_____ a share (the "Purchase Price") the number of Firm Shares set
forth in Schedule I hereto opposite the name of such Underwriter.

On the basis of the representations and warranties contained in this
Agreement, and subject to its terms and conditions, the Company agrees to sell
to the Underwriters the Additional Shares, and the Underwriters shall have a
one-time right to purchase, severally and not jointly, up to 300,000 Additional
Shares at the Purchase Price. If you, on behalf of the Underwriters, elect to
exercise such option, you shall so notify the Company in writing not later than
30 days after the date of this Agreement, which notice shall specify the number
of Additional Shares to be purchased by the Underwriters and the date on which
such shares are to be purchased. Such date may be the same as the Closing Date
(as defined below) but not earlier than the Closing Date nor later than ten
business days after the date of such notice. Additional Shares may be purchased
as provided in Section 4 hereof solely for the purpose of covering
over-allotments made in connection with the offering of the Firm Shares. If any
Additional Shares are to be purchased, each Underwriter agrees, severally and
not jointly, to purchase the number of Additional Shares (subject to such
adjustments to eliminate fractional shares as you may determine) that bears the
same proportion to the total number of Additional Shares to be purchased as the
number of Firm Shares set forth in Schedule I hereto opposite the name of such
Underwriter bears to the total number of Firm Shares.

The Company hereby agrees that, without the prior written consent of Morgan
Stanley & Co. Incorporated on behalf of the Underwriters, it will not, during
the period ending 90 days after the date of the Prospectus, (i) offer, pledge,
lend, sell, contract to sell, sell any option or contract to purchase, purchase
any option or contract to sell, grant any option, right or warrant to purchase,
or otherwise transfer or dispose of, directly or indirectly, any shares of

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<PAGE> 9
Common Stock or any securities convertible into or exercisable or exchangeable
for Common Stock or (ii) enter into any swap or other arrangement that transfers
to another, in whole or in part, the economic consequences of ownership of the
Common Stock, whether any such transaction described in clause (i) or (ii) above
is to be settled by delivery of Common Stock or such other securities, in cash
or otherwise, other than (a) the Shares to be offered hereunder, (b) any shares
of Common Stock sold or issued upon exercise of an option or warrant or the
conversion of a security outstanding on the date hereof described in the
Prospectus or of which the Underwriters have been advised in writing, (c) shares
of Common Stock to be registered pursuant to a Registration Statement on Form
S-8, or (d) the grant of options pursuant to the Company's 1988 Employee Stock
Option Plan or the 1993 Non-Employee Directors Stock Option Plan as to shares
reserved for issuance under such plans as of the Closing, including any shares
subject to outstanding options which become available for future grant under
such plans upon termination of previously issued options. The foregoing sentence
shall not apply to the Shares to be sold hereunder.

3. TERMS OF PUBLIC OFFERING. The Company is advised by you that the
Underwriters propose to make a public offering of their respective portions of
the Shares as soon after the Registration Statement and this Agreement have
become effective as in your judgment is advisable. The Company is further
advised by you that the Shares are to be offered to the public initially at
$_____ a share (the "Public Offering Price") and to certain dealers selected by
you at a price that represents a concession not in excess of $_____ a share
under the Public Offering Price, and that any Underwriter may allow, and such
dealers may reallow, a concession, not in excess of $_____ a share, to any
Underwriter or to certain other dealers.

4. PAYMENT AND DELIVERY. Payment for the Firm Shares to be sold by the
Company shall be made to the Company in Federal or other funds immediately
available in New York City against delivery of such Firm Shares for the
respective accounts of the several Underwriters at 10:00 A.M., New York City
time, on _______ __, 1998, or at such other time on the same or such other date,
not later than _______ __, 1998, as shall be designated in writing by you. The
time and date of such payment are hereinafter referred to as the "Closing Date."

Payment for any Additional Shares shall be made to the Company in Federal
or other funds immediately available in New York City against delivery of such
Additional Shares for the respective accounts of the several Underwriters at
10:00 A.M., New York City time, on the date specified in the notice described in
Section 2 or on such other date, in any event not later than _______ __, 1998,
as shall be designated in writing by you. The time and date of such payment are
hereinafter referred to as the "Option Closing Date."

Certificates for the Firm Shares and Additional Shares shall be in
definitive form and registered in such names and in such denominations as you
shall request in writing not later than one full business day prior to the
Closing Date or the Option Closing Date, as the case may be. The certificates
evidencing the Firm Shares and Additional Shares shall be delivered to you on
the Closing Date or the Option Closing Date, as the case may be, for the
respective accounts of the several Underwriters, with any transfer taxes payable
in connection with the transfer of the Shares to the Underwriters duly paid,
against payment of the Purchase Price therefor.

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<PAGE> 10
5. CONDITIONS TO THE UNDERWRITER' OBLIGATIONS. The obligations of the
Company to sell the Shares to the Underwriters and the several obligations of
the Underwriters to purchase and pay for the Shares on the Closing Date are
subject to the condition that the Registration Statement shall have become
effective not later than 4:30 p.m. (New York City time) on the date hereof.

The several obligations of the Underwriters are subject to the following
further conditions:

(a) Subsequent to the execution and delivery of this Agreement and
prior to the Closing Date:

(i) there shall not have occurred any downgrading, nor shall any
notice have been given of any intended or potential downgrading or of any review
for a possible change that does not indicate the direction of the possible
change, in the rating accorded any of the Company's securities by any
"nationally recognized statistical rating organization," as such term is defined
for purposes of Rule 436(g)(2) under the Securities Act; and

(ii) there shall not have occurred any change, or any development
involving a prospective change, in the condition, financial or otherwise, or in
the earnings, business or operations of the Company and the Subsidiary, taken as
a whole, from that set forth in the Prospectus that, in your judgment, is
material and adverse and that makes it, in your judgment, impracticable to
market the Shares on the terms and in the manner contemplated in the Prospectus.

(b) The Underwriters shall have received on the Closing Date a
certificate, dated the Closing Date and signed by an executive officer of the
Company, to the effect set forth in clause (a)(i) above and to the effect that
the representations and warranties of the Company contained in this Agreement
are true and correct as of the Closing Date and that the Company has complied
with all of the agreements and satisfied all of the conditions on its part to be
performed or satisfied hereunder on or before the Closing Date.

The officer signing and delivering such certificate may rely upon the best
of his or her knowledge as to proceedings threatened.

(c) The Underwriters shall have received on the Closing Date an
opinion of Brobeck, Phleger & Harrison LLP, outside counsel for the Company,
dated the Closing Date, to the effect that:

(i) the Company has been duly incorporated and is validly
existing as a corporation in good standing under the laws of the State of
Delaware, with full corporate power and authority to own or lease its properties
and conduct its business as described in the Registration Statement and
Prospectus;

(ii) other than the Subsidiary, the Company has no subsidiaries;

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<PAGE> 11
(iii) the authorized capital stock of the Company conforms as to
legal matters in all material respects to the description thereof contained in
the Registration Statement and Prospectus;

(iv) the outstanding shares of capital stock of the Company have
been duly and validly authorized and issued, and are not subject to any
preemptive or similar rights;

(v) the shares to be sold by the Company have been duly
authorized and, when issued and delivered in accordance with the terms of this
agreement, will be duly and validly authorized and issued, fully paid and
nonassessable, and will not be subject to any preemptive or similar rights;

(vi) to the best of such counsel's knowledge, after due inquiry,
no holders of securities of the Company have rights against the Company which
have not been waived to the registration of shares of Common Stock or other
securities because of the filing of the Registration Statement by the Company or
the offering contemplated thereby;

(vii) this agreement has been duly authorized, executed and
delivered by the Company;

(viii) the execution and delivery by the Company of, and the
performance by the Company of its obligations under this agreement will not
contravene any provision of applicable law or the certificate of incorporation
or bylaws of the Company or the Subsidiary, or, to the best of such counsel's
knowledge, any judgment, order or decree of any governmental body, agency or
court having jurisdiction over the Company or any of its property or the
Subsidiary or any of its property, or, to the best of such counsel's knowledge,
constitute a breach or default under any Material Agreement, and no consent,
approval, authorization or order of or qualification with any governmental body
or agency is required for the performance by the Company of its obligations
under this agreement, except such as may be required by the securities or blue
sky laws of the various states (on which such counsel expresses no opinion) in
connection with the purchase and distribution of the shares by the Underwriters;

(ix) the statements (a) in the Prospectus under the captions
"Description of Capital Stock" and "Business -- Strategic Alliances" and (b) in
the Registration Statement in Item 15, in each case insofar as such statements
constitute summaries of the legal matters, documents or proceedings referred to
therein, fairly present the information called for with respect to such legal
matters, documents and proceedings and fairly summarize the matters referred to
therein;

(x) such counsel does not know of any legal or governmental
proceeding pending or threatened to which the Company or the Subsidiary is or
may become a party or to which any of the properties of the Company or any of
the properties of the Subsidiary is or may become subject that is required to be
described in the Registration Statement or the Prospectus and is not so
described, or of any statute, regulation, contract or other document that

10
<PAGE> 12
is required to be described in the Registration Statement or the Prospectus or
to be filed as an exhibit to the Registration Statement that is not described or
filed as required; and

(xi) the Registration Statement has become effective under the
Securities Act, and no stop order proceedings suspending the effectiveness of
the Registration Statement have been instituted or threatened or are pending
under the Securities Act and any required filing of the Prospectus and any
supplement thereto pursuant to Rule 424(b) under the Securities Act has been
made in the manner and within the time period required by such Rule 424(b).

In addition to rendering legal advice and assistance to the Company in the
course of the preparation of the Registration Statement and the Prospectus,
involving, among other things, discussions and inquiries concerning various
legal matters and the review of certain corporate records, documents and
proceedings such counsel also participated in conferences with certain officers
and other representatives of the Company, including its independent public
accountants and with the Underwriters and their counsel at which the contents of
the Registration Statement, the Prospectus (but not including the incorporated
documents) and related matters were discussed and have generally reviewed and
discussed with such persons the content of the incorporated documents. Such
counsel has not, however, except with respect to matters expressly covered by
this opinion, independently checked or verified the accuracy, completeness or
fairness of the information contained in the Registration Statement, the
Prospectus and the incorporated documents.

In addition to the matters set forth above, counsel rendering the foregoing
opinion shall also include a statement to the effect that nothing has come to
the attention of such counsel that causes it to believe that (i) each of the
incorporated documents (except for financial statements) complied as to form
when filed with the Commission in all material respects with the requirements of
the Securities Act and the Securities Exchange Act of 1934, as amended (the
"Exchange Act"), as applicable, and the rules and regulations of the Commission
thereunder; (ii) the Registration Statement and the Prospectus (except for the
financial statements), as of the effective date of the Registration Statement,
complied as to form in all material respects with the requirements of the
Securities Act and the applicable rules and regulations of the Commission
thereunder; and (iii) neither the Registration Statement nor the Prospectus
(except for the financial statements), as of such effective date, contained any
untrue statement of a material fact or omitted to state a material fact required
to be stated therein or necessary to make the statements therein not misleading
or that (except for the financial statements) the Prospectus, as of the Closing
Date, contains any untrue statement of a material fact or omits to state a
material fact necessary in order to make the statements therein, in light of the
circumstances under which they were made, not misleading.

(d) You shall have received on the Closing Date the opinion of Burns,
Doane, Sweeker & Mathis, intellectual property counsel for the Company, dated
the Closing Date, to the effect that:

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(i) to the best of such counsel's knowledge, such counsel is not
aware of any legal actions, claims or proceedings pending or threatened against
the Company alleging that the Company is infringing or otherwise violating any
patents or trade secrets owned by others and to the best of such counsel's
knowledge, the Company has not received any communication in which it is alleged
that the Company is infringing or violating the patent rights of third parties;

(ii) the portions of the Registration Statement entitled "Risk
Factors -- Patents and Proprietary Rights" and "Business -- Patents and
Proprietary Rights" (collectively, the "Intellectual Property Portion") contain
accurate and complete descriptions of the Company's patent applications, issued
and allowed patents, and patents licensed to the Company and fairly summarized
the legal matters, documents and proceedings relating thereto;

(iii) to the best of such counsel's knowledge, at least ____
United States patent has issued to the Company, and that the Company is the
Assignee of record, and that the patent is being maintained by the Company;

(iv) to the best of such counsel's knowledge, at least ____
additional U.S. patent applications have been filed by the Company in the U.S.
Patent and Trademark Office; that those pending patent applications have been
properly prepared as to form and have been assigned to the Company which
Assignments are either recorded in the U.S. Patent and Trademark Office or have
been submitted for recording in the U.S. Patent and Trademark Office; and that
each of these patent applications is being pursued by the Company;

(v) with respect to patent applications that have assignments to
the Company and other entities, the Company has obtained appropriate licenses
from such other entities;

(vi) to the best of such counsel's knowledge, ____ foreign
counterpart patent applications have been filed on behalf of the Company;

(vii) to the extent that the Intellectual Property Portion
contains descriptions which constitute matters of law or legal conclusions,
these descriptions are correct in all material respects and fairly present the
patent situation of the Company;

(viii) to the best of such counsel's knowledge, there are no
legal or governmental proceedings other than patent applications pending,
relating to patent rights of the Company to which the Company is a party and, to
such counsel's knowledge, no such proceedings are threatened or contemplated by
governmental authorities or others;

(ix) although such counsel has not conducted all necessary
freedom of operation opinions, to the best of such counsel's knowledge, all
patents held by third parties, of which such counsel is aware, that could
prevent the Company from manufacturing and selling, in the United States and
abroad, the compositions and methods claimed in the patent applications
described in an exhibit to such counsel's opinion, have been disclosed by such
counsel in the Registration Statement or the Prospectus;

12
<PAGE> 14
(x) in addition, although such counsel has not independently
verified the accuracy, completeness or fairness of the statements contained in
the Registration Statement or the Prospectus (except that such counsel has
independently verified the accuracy of the matters contained in subsections
(iii), (iv) and (vi) of this paragraph (d)), nothing has come to such counsel's
attention that leads such counsel to believe that the statements in the
Intellectual Property Portion in (a) the Registration Statement, at the time it
became effective or at the Closing Date, contained or contain an untrue
statement of a material fact or omit or omitted to state a material fact
required to be stated therein or necessary to make the statements therein not
misleading as to intellectual property matters, or (b) the Prospectus, as of the
date of the Prospectus or at the Closing Date, contained or contain an untrue
statement of a material fact or omitted or omit to state a material fact
required to be stated therein or necessary to make the statements therein, in
light of the circumstances under which they were made, not misleading as to
intellectual property matters (it being understood that such counsel has not
participated in the negotiation of or reviewed the Company's license agreements
and such counsel has not undertaken any independent investigation as to whether
the Company is infringing any patents or other rights of others or whether the
Company owns or possesses sufficient licenses or other rights to use all patents
or other rights necessary for the conduct of the Company's business).

(e) you shall have received on the Closing Date an opinion of Buc &
Beardsley, regulatory affairs counsel for the Company, dated the Closing Date,
to the effect that:

(i) the statements in the Prospectus under the captions "Risk
Factors -- Lengthy Regulatory Process; No Assurance of Additional Regulatory
Approvals" and "Business -- Government Regulation," and footnote one to the
table under "Business -- Products and Products Under Development" (the
"Regulatory Portion") insofar as they refer to statements summarizing applicable
provisions of the Federal Food, Drug, and Cosmetic Act (FDCA), as amended Public
Health Service Act (PHSA), and implementing regulations are correct in all
material respects.

(ii) in addition, although such counsel has made no independent
inquiry, nothing has come to such counsel's attention that would lead such
counsel to believe that the statements in the Regulatory Portion of (a) the
Registration Statement, at the time it became effective or at the Closing Date,
contained or contain an untrue statement of a material fact or omit or omitted
to state a material fact required to be stated therein or necessary to make the
statements therein not misleading, or (b) the Prospectus, as of the date of the
Prospectus or at the Closing Date, contained or contain an untrue statement of a
material fact or omitted or omit to state a material fact required to be stated
therein or necessary to make the statements therein, in light of the
circumstances under which they were made, not misleading.

(f) You shall have received on the Closing Date an opinion of
Gunderson Dettmer Stough Villeneuve Franklin & Hachigian, LLP, counsel for the
Underwriters, dated the Closing Date, covering the matters referred to in
subparagraphs (v), (vii), (ix) (but only as to the statements in the Prospectus
under "Description of Capital Stock" and "Underwriters"), and the second
paragraph following the enumerated opinions in paragraph (c)

13
<PAGE> 15
above (but only as to subparagraphs (ii) and (iii) of the second paragraph
following the enumerated opinions in paragraph (c) above).

With respect to the second paragraph following the enumerated opinions in
paragraph (c) above and paragraph (f) above, Brobeck, Phleger & Harrison LLP and
Gunderson Dettmer Stough Villeneuve Franklin & Hachigian, LLP may state that
their opinion and belief are based upon their participation in the preparation
of the Registration Statement and Prospectus and any amendments or supplements
thereto and review and discussion of the contents thereof, but are without
independent check or verification, except as specified.

The opinions of Burns, Doane, Sweeker & Mathis and Buc & Beardsley
described in paragraphs (d) and (e) above shall be rendered to the Underwriters
at the request of the Company and shall so state therein.

(g) The Underwriters shall have received, on each of the date hereof
and the Closing Date, a letter dated the date hereof or the Closing Date, as the
case may be, in form and substance satisfactory to the Underwriters, from KPMG
Peat Marwick LLP, independent public accountants, containing statements and
information of the type ordinarily included in accountants' "comfort letters" to
underwriters with respect to the financial statements and certain financial
information contained in the Registration Statement and the Prospectus; provided
that the letter delivered on the Closing Date shall use a "cut-off date" not
earlier than the date hereof.

(h) The "lock-up" agreements, each substantially in the form of
Exhibit A hereto, between you and certain shareholders, officers and directors
of the Company relating to sales and certain other dispositions of shares of
Common Stock or certain other securities, delivered to you on or before the date
hereof, shall be in full force and effect on the Closing Date.

The several obligations of the Underwriters to purchase Additional Shares
hereunder are subject to the delivery to you on the Option Closing Date of such
documents as you may reasonably request with respect to the good standing of the
Company, the due authorization and issuance of the Additional Shares and other
matters related to the issuance of the Additional Shares.

6. COVENANTS OF THE COMPANY. In further consideration of the agreements of
the Underwriters herein contained, the Company covenants with each Underwriter
as follows:

(a) To furnish to you, without charge, three (3) signed copies (in
original or by facsimile) of the Registration Statement (including exhibits
thereto) and for delivery to each other Underwriter a conformed copy of the
Registration Statement (without exhibits thereto) and to furnish to you in New
York City, without charge, prior to 3:00 P.M. New York City time on the business
day next succeeding the date of this Agreement and during the period mentioned
in paragraph (c) below, as many copies of the Prospectus and any supplements and
amendments thereto or to the Registration Statement as you may reasonably
request.

14
<PAGE> 16
(b) Before amending or supplementing the Registration Statement or the
Prospectus, to furnish to you a copy of each such proposed amendment or
supplement and not to file any such proposed amendment or supplement to which
you reasonably object, and to file with the Commission within the applicable
period specified in Rule 424(b) under the Securities Act any prospectus required
to be filed pursuant to such Rule.

(c) If, during such period after the first date of the public offering
of the Shares as in the reasonable opinion of counsel for the Underwriters the
Prospectus is required by law to be delivered in connection with sales by an
Underwriter or dealer, any event shall occur or condition exist as a result of
which it is necessary to amend or supplement the Prospectus in order to make the
statements therein, in the light of the circumstances when the Prospectus is
delivered to a purchaser, not misleading, or if, in the opinion of counsel for
the Underwriters, it is necessary to amend or supplement the Prospectus to
comply with applicable law, forthwith to prepare, file with the Commission and
furnish, at its own expense, to the Underwriters and to the dealers (whose names
and addresses you will furnish to the Company) to which Shares may have been
sold by you on behalf of the Underwriters and to any other dealers upon request,
either amendments or supplements to the Prospectus so that the statements in the
Prospectus as so amended or supplemented will not, in the light of the
circumstances when the Prospectus is delivered to a purchaser, be misleading or
so that the Prospectus, as amended or supplemented, will comply with law.

(d) To endeavor to qualify the Shares for offer and sale under the
securities or Blue Sky laws of such jurisdictions as you shall reasonably
request.

(e) To make generally available to the Company's security holders and
to you as soon as practicable an earning statement covering the twelve-month
period ending _______ __, 199_ that satisfies the provisions of Section 11(a) of
the Securities Act and the rules and regulations of the Commission thereunder.

(f) Whether or not the transactions contemplated in this Agreement are
consummated or this Agreement is terminated, to pay or cause to be paid all
expenses incident to the performance of its obligations under this Agreement,
including: (i) the fees, disbursements and expenses of the Company's counsel and
the Company's accountants in connection with the registration and delivery of
the Shares under the Securities Act and all other fees or expenses in connection
with the preparation and filing of the Registration Statement, any preliminary
prospectus, the Prospectus and amendments and supplements to any of the
foregoing, including all printing costs associated therewith, and the mailing
and delivering of copies thereof to the Underwriters and dealers, in the
quantities hereinabove specified, (ii) all costs and expenses related to the
transfer and delivery of the Shares to the Underwriters, including any transfer
or other taxes payable thereon, (iii) the cost of printing or producing any Blue
Sky or Legal Investment memorandum in connection with the offer and sale of the
Shares under state securities laws and all expenses in connection with the
qualification of the Shares for offer and sale under state securities laws as
provided in Section 6(d) hereof, including filing fees and the reasonable fees
and disbursements of counsel for the Underwriters in connection with such
qualification and in connection with the Blue Sky or Legal Investment
memorandum,

15
<PAGE> 17
(iv) all filing fees and disbursements of counsel to the Underwriters incurred
in connection with the review and qualification of the offering of the Shares by
the National Association of Securities Dealers, Inc., (v) all costs and expenses
incident to listing the Shares on Nasdaq National Market, (vi) the cost of
printing certificates representing the Shares, (vii) the costs and charges of
any transfer agent, registrar or depositary, (viii) the costs and expenses of
the Company relating to investor presentations on any "road show" undertaken in
connection with the marketing of the offering of the Shares, including, without
limitation, expenses associated with the production of road show slides and
graphics, fees and expenses of any consultants engaged in connection with the
road show presentations with the prior approval of the Company, travel and
lodging expenses of the representatives and officers of the Company and any such
consultants, and the cost of any aircraft chartered in connection with the road
show, and (ix) all other costs and expenses incident to the performance of the
obligations of the Company hereunder for which provision is not otherwise made
in this Section. It is understood, however, that except as provided in this
Section, Section 7 entitled "Indemnity and Contribution", and the last paragraph
of Section 9 below, the Underwriters will pay all of their costs and expenses,
including fees and disbursements of their counsel, stock transfer taxes payable
on resale of any of the Shares by them and any advertising expenses connected
with any offers they may make.

(g) To not release any shares of Common Stock from any restrictions
imposed upon such shares by the Lock-Up Agreements without the prior written
consent of Morgan Stanley.

7. INDEMNITY AND CONTRIBUTION.

(a) The Company agrees to indemnify and hold harmless each Underwriter
and each person, if any, who controls any Underwriter within the meaning of
either Section 15 of the Securities Act or Section 20 of the Exchange Act from
and against any and all losses, claims, damages and liabilities (including,
without limitation, any legal or other expenses reasonably incurred by any
Underwriter or any such controlling person in connection with defending or
investigating any such action or claim) caused by any untrue statement or
alleged untrue statement of a material fact contained in the Registration
Statement or any amendment thereof, any preliminary prospectus or the Prospectus
(as amended or supplemented if the Company shall have furnished any amendments
or supplements thereto), or caused by any omission or alleged omission to state
therein a material fact required to be stated therein or necessary to make the
statements therein not misleading, except insofar as such losses, claims,
damages or liabilities are caused by any such untrue statement or omission or
alleged untrue statement or omission based upon information relating to any
Underwriter furnished to the Company in writing by such Underwriter through you
expressly for use therein; provided, however, that the foregoing indemnity
agreement with respect to any preliminary prospectus shall not inure to the
benefit of any Underwriter, or any person controlling such Underwriter, from
whom that person asserting any such losses, claims, damages or liabilities
purchased Shares, if a copy of the Prospectus (as then amended or supplemented
if the Company shall have furnished any amendments or supplements thereto) was
not sent or given by or on behalf of such Underwriter to such person, if
required by law so to have been delivered, at or prior to the written

16
<PAGE> 18
confirmation of the sale of the Shares to such person, and if the Prospectus (as
so amended or supplemented) would have cured the defect giving rise to such
loss, claim, damage or liability.

(b) Each Underwriter agrees, severally and not jointly, to indemnify
and hold harmless the Company, each of the directors of the Company, each of the
officers of the Company who sign the Registration Statement and each person, if
any, who controls the Company within the meaning of either Section 15 of the
Securities Act or Section 20 of the Exchange Act from and against any and all
losses, claims, damages and liabilities (including, without limitation, any
legal or other expenses reasonably incurred in connection with defending or
investigating any such action or claim) caused by any untrue statement or
alleged untrue statement of a material fact contained in the Registration
Statement or any amendment thereof, any preliminary prospectus or the Prospectus
(as amended or supplemented if the Company shall have furnished any amendments
or supplements thereto), or caused by any omission or alleged omission to state
therein a material fact required to be stated therein or necessary to make the
statements therein not misleading, but only with reference to information
relating to such Underwriter furnished to the Company in writing by such
Underwriter through you expressly for use in the Registration Statement, any
preliminary prospectus, the Prospectus or any amendments or supplements thereto.

(c) In case any proceeding (including any governmental investigation)
shall be instituted involving any person in respect of which indemnity may be
sought pursuant to paragraph (a) or (b) of this Section 7, such person (the
"indemnified party") shall promptly notify the person against whom such
indemnity may be sought (the "indemnifying party") in writing and the
indemnifying party, upon request of the indemnified party, shall retain counsel
reasonably satisfactory to the indemnified party to represent the indemnified
party and any others the indemnifying party may designate in such proceeding and
shall pay the fees and disbursements of such counsel related to such proceeding.
In any such proceeding, any indemnified party shall have the right to retain its
own counsel, but the fees and expenses of such counsel shall be at the expense
of such indemnified party unless (i) the indemnifying party and the indemnified
party shall have mutually agreed to the retention of such counsel or (ii) the
named parties to any such proceeding (including any impleaded parties) include
both the indemnifying party and the indemnified party and representation of both
parties by the same counsel would be inappropriate due to actual or potential
differing interests between them. It is understood that the indemnifying party
shall not, in respect of the legal expenses of any indemnified party in
connection with any proceeding or related proceedings in the same jurisdiction,
be liable for the fees and expenses of more than one separate firm (in addition
to any local counsel) for (i) all Underwriters and all persons, if any, who
control any Underwriter within the meaning of either Section 15 of the
Securities Act or Section 20 of the Exchange Act, and (ii) the Company, its
directors, its officers who sign the Registration Statement and each person, if
any, who controls the Company within the meaning of either such Section and that
all such fees and expenses shall be reimbursed as they are incurred. In the case
of any such separate firm for the Underwriters and such control persons of the
Underwriters, such firm shall be designated in writing by Morgan Stanley & Co.
Incorporated. In the case of any such separate firm for the Company, and such
directors, officers and control persons of the Company, such firm shall be
designated in writing by the Company. The indemnifying party shall not be liable
for any

17
<PAGE> 19
settlement of any proceeding effected without its written consent, but if
settled with such consent or if there be a final judgment for the plaintiff, the
indemnifying party agrees to indemnify the indemnified party from and against
any loss or liability by reason of such settlement or judgment. Notwithstanding
the foregoing sentence, if at any time an indemnified party shall have requested
an indemnifying party to reimburse the indemnified party for fees and expenses
of counsel as contemplated by the second and third sentences of this paragraph,
the indemnifying party agrees that it shall be liable for any settlement of any
proceeding effected without its written consent if (i) such settlement is
entered into more than 30 days after receipt by such indemnifying party of the
aforesaid request and (ii) such indemnifying party shall not have reimbursed the
indemnified party in accordance with such request prior to the date of such
settlement. No indemnifying party shall, without the prior written consent of
the indemnified party, effect any settlement of any pending or threatened
proceeding in respect of which any indemnified party is or could have been a
party and indemnity could have been sought hereunder by such indemnified party,
unless such settlement includes an unconditional release of such indemnified
party from all liability on claims that are the subject matter of such
proceeding.

(d) To the extent the indemnification provided for in paragraph (a) or
(b) of this Section 7 is unavailable to an indemnified party or insufficient in
respect of any losses, claims, damages or liabilities referred to therein, then
each indemnifying party under such paragraph, in lieu of indemnifying such
indemnified party thereunder, shall contribute to the amount paid or payable by
such indemnified party as a result of such losses, claims, damages or
liabilities (i) in such proportion as is appropriate to reflect the relative
benefits received by the indemnifying party or parties on the one hand and the
indemnified party or parties on the other hand from the offering of the Shares
or (ii) if the allocation provided by clause (i) above is not permitted by
applicable law, in such proportion as is appropriate to reflect not only the
relative benefits referred to in clause (i) above but also the relative fault of
the indemnifying party or parties on the one hand and of the indemnified party
or parties on the other hand in connection with the statements or omissions that
resulted in such losses, claims, damages or liabilities, as well as any other
relevant equitable considerations. The relative benefits received by the Company
on the one hand and the Underwriters on the other hand in connection with the
offering of the Shares shall be deemed to be in the same respective proportions
as the net proceeds from the offering of the Shares (before deducting expenses)
received by the Company and the total underwriting discounts and commissions
received by the Underwriters, in each case as set forth in the table on the
cover of the Prospectus, bear to the aggregate Public Offering Price of the
Shares. The relative fault of the Company on the one hand and the Underwriters
on the other hand shall be determined by reference to, among other things,
whether the untrue or alleged untrue statement of a material fact or the
omission or alleged omission to state a material fact relates to information
supplied by the Company or by the Underwriters and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent such
statement or omission. The Underwriters' respective obligations to contribute
pursuant to this Section 7 are several in proportion to the respective number of
Shares they have purchased hereunder, and not joint.

(e) The Company and the Underwriters agree that it would not be just
or equitable if contribution pursuant to this Section 7 were determined by pro
rata allocation

18
<PAGE> 20
(even if the Underwriters were treated as one entity for such purpose) or by any
other method of allocation that does not take account of the equitable
considerations referred to in paragraph (d) of this Section 7. The amount paid
or payable by an indemnified party as a result of the losses, claims, damages
and liabilities referred to in the immediately preceding paragraph shall be
deemed to include, subject to the limitations set forth above, any legal or
other expenses reasonably incurred by such indemnified party in connection with
investigating or defending any such action or claim. Notwithstanding the
provisions of this Section 7, no Underwriter shall be required to contribute any
amount in excess of the amount by which the total price at which the Shares
underwritten by it and distributed to the public were offered to the public
exceeds the amount of any damages that such Underwriter has otherwise been
required to pay by reason of such untrue or alleged untrue statement or omission
or alleged omission. No person guilty of fraudulent misrepresentation (within
the meaning of Section 11(f) of the Securities Act) shall be entitled to
contribution from any person who was not guilty of such fraudulent
misrepresentation. The remedies provided for in this Section 7 are not exclusive
and shall not limit any rights or remedies which may otherwise be available to
any indemnified party at law or in equity.

(f) The indemnity and contribution provisions contained in this
Section 7 and the representations, warranties and other statements of the
Company contained in this Agreement shall remain operative and in full force and
effect regardless of (i) any termination of this Agreement, (ii) any
investigation made by or on behalf of any Underwriter or any person controlling
any Underwriter, or the Company, its officers or directors or any person
controlling the Company and (iii) acceptance of and payment for any of the
Shares.

8. TERMINATION. This Agreement shall be subject to termination by notice
given by you to the Company, if (a) after the execution and delivery of this
Agreement and prior to the Closing Date (i) trading generally shall have been
suspended or materially limited on or by, as the case may be, any of the New
York Stock Exchange, the American Stock Exchange, the National Association of
Securities Dealers, Inc., the Chicago Board of Options Exchange, the Chicago
Mercantile Exchange or the Chicago Board of Trade, (ii) trading of any
securities of the Company shall have been suspended on any exchange or in any
over-the-counter market, (iii) a general moratorium on commercial banking
activities in New York shall have been declared by either Federal or New York
State authorities or (iv) there shall have occurred any outbreak or escalation
of hostilities or any change in financial markets or any calamity or crisis
that, in your judgment, is material and adverse and (b) in the case of any of
the events specified in clauses (a) (i) through (iv), such event, singly or
together with any other such event, makes it, in your judgment, impracticable to
market the Shares on the terms and in the manner contemplated in the Prospectus.

9. EFFECTIVENESS: DEFAULTING UNDERWRITERS. This Agreement shall become
effective upon the execution and delivery hereof by the parties hereto.

If, on the Closing Date or the Option Closing Date, as the case may be, any
one or more of the Underwriters shall fail or refuse to purchase Shares that it
has or they have agreed to purchase hereunder on such date, and the aggregate
number of Shares which such defaulting Underwriter or Underwriters agreed but
failed or refused to purchase is not more than one-tenth

19
<PAGE> 21
of the aggregate number of the Shares to be purchased on such date, the other
Underwriters shall be obligated severally in the proportions that the number of
Firm Shares set forth opposite their respective names in Schedule I bears to the
aggregate number of Firm Shares set forth opposite the names of all such
non-defaulting Underwriters, or in such other proportions as you may specify, to
purchase the Shares which such defaulting Underwriter or Underwriters agreed but
failed or refused to purchase on such date; provided that in no event shall the
number of Shares that any Underwriter has agreed to purchase pursuant to this
Agreement be increased pursuant to this Section 9 by an amount in excess of
one-ninth of such number of Shares without the written consent of such
Underwriter.

If, on the Closing Date, any Underwriter or Underwriters shall fail or
refuse to purchase Firm Shares and the aggregate number of Firm Shares with
respect to which such default occurs is more than one-tenth of the aggregate
number of Firm Shares to be purchased, and arrangements satisfactory to you and
the Company for the purchase of such Firm Shares are not made within 36 hours
after such default, this Agreement shall terminate without liability on the part
of any non-defaulting Underwriter or the Company. In any such case you shall
have the right to postpone the Closing Date, but in no event for longer than
seven days, in order that the required changes, if any, in the Registration
Statement and in the Prospectus or in any other documents or arrangements may be
effected. If, on the Option Closing Date, any Underwriter or Underwriters shall
fail or refuse to purchase Additional Shares and the aggregate number of
Additional Shares with respect to which such default occurs is more than
one-tenth of the aggregate number of Additional Shares to be purchased, the
non-defaulting Underwriters shall have the option to (i) terminate their
obligation hereunder to purchase Additional Shares or (ii) purchase not less
than the number of Additional Shares that such non-defaulting Underwriters would
have been obligated to purchase in the absence of such default. Any action taken
under this paragraph shall not relieve any defaulting Underwriter from liability
in respect of any default of such Underwriter under this Agreement.

If this Agreement shall be terminated by the Underwriters, or any of them,
because of any failure or refusal on the part of the Company to comply with the
terms or to fulfill any of the conditions of this Agreement, or if for any
reason the Company shall be unable to perform its obligations under this
Agreement, the Company will reimburse the Underwriters or such Underwriters as
have so terminated this Agreement with respect to themselves, severally, for all
out-of-pocket expenses (including the fees and disbursements of their counsel)
reasonably incurred by such Underwriters in connection with this Agreement or
the offering contemplated hereunder.

10. COUNTERPARTS. This Agreement may be signed in two or more counterparts,
each of which shall be an original, with the same effect as if the signatures
thereto and hereto were upon the same instrument.

11. APPLICABLE LAW. This Agreement shall be governed by and construed in
accordance with the internal laws of the State of New York.

20
<PAGE> 22
12. HEADINGS. The headings of the sections of this Agreement have been
inserted for convenience of reference only and shall not be deemed a part of
this Agreement.

Very truly yours,

IDEC PHARMACEUTICALS CORPORATION

By:
--------------------------------
Name: William H. Rastetter
Title: Chairman, CEO and President

Accepted as of the date hereof

Morgan Stanley & Co. Incorporated
Nationsbanc Montgomery Securities, Inc.

Acting severally on behalf
of themselves and the
several underwriters named
in Schedule I hereto.

By Morgan Stanley & Co.
Incorporated

By:
------------------------------
Name: Cathy Friedman
Title: Managing Director

<PAGE> 23
SCHEDULE I

<TABLE>
<CAPTION>
NUMBER OF
FIRM SHARES
UNDERWRITER TO BE PURCHASED
- ----------- ---------------
<S> <C>
Morgan Stanley & Co. Incorporated..........................................
Nationsbanc Montgomery Securities LLC......................................

---------------
Total Firm Shares 2,000,000
===============
</TABLE>

S-1
<PAGE> 24
EXHIBIT A

IDEC PHARMACEUTICALS CORPORATION
LOCK-UP LETTER

February __, 1997

Morgan Stanley & Co. Incorporated
Nationsbanc Montgomery Securities, Inc.
c/o Morgan Stanley & Co. Incorporated
1585 Broadway
New York, NY 10036

Ladies and Gentlemen:

The undersigned understands that you, as representatives (the
"Representatives") of the several underwriters (the "Underwriters"), propose to
enter into an Underwriting Agreement with IDEC Pharmaceuticals Corporation (the
"Company") providing for the public offering (the "Public Offering") by the
several Underwriters, including yourselves, of common stock of the Company (the
"Common Stock").

To induce the Underwriters that may participate in the Public Offering
of the Company's Common Stock to continue their efforts in connection with the
Public Offering, the undersigned hereby agrees that, without the prior written
consent of Morgan Stanley & Co. Incorporated on behalf of the Underwriters, it
will not, during the period ending ninety (90) days after the date of the
Prospectus, (1) offer, pledge, lend, sell, contract to sell, sell any option or
contract to purchase, purchase any option or contract to sell, grant any option,
right or warrant to purchase, or otherwise transfer or dispose of, directly or
indirectly, any shares of Common Stock or any securities convertible into or
exercisable or exchangeable for Common Stock, or (2) enter into any swap or
other arrangement that transfers to another, in whole or in part, the economic
consequences of ownership of the Common Stock, whether any such transaction
described in clause (1) or (2) above is to be settled by delivery of Common
Stock or such other securities, in cash or otherwise. The foregoing sentence
shall not apply to the sale of any shares to the Underwriters pursuant to the
Underwriting Agreement. In addition, the undersigned agrees that, without the
prior written consent of Morgan Stanley & Co. Incorporated on behalf of the
Underwriters, it will not, during the period ending ninety (90) days after the
date of the final Prospectus for the Public Offering, make any demand for or
exercise any right with respect to, the registration of any shares of Common
Stock or any security convertible into or exercisable or exchangeable for Common
Stock.

The undersigned confirms that the agreements of the undersigned are
irrevocable and shall be binding upon the undersigned's legal representatives
successors and assigns. The

E-1
<PAGE> 25
undersigned agrees and consents to the entry of stop transfer instructions with
the Company's transfer agent against the transfer of securities of the Company
held by the undersigned except in compliance with the terms and condition of
this Agreement.

Whether or not the Public Offering actually occurs depends on a number
of factors, including market conditions. Any Public Offering will only be made
pursuant to an Underwriting Agreement, the terms of which are subject to
agreement between the Company and the Underwriters.

Very truly yours,

-----------------------------------
(Signature)

-----------------------------------
(Print Name)

Address:
-----------------------------------

-----------------------------------

E-2

<PAGE> 1
EXHIBIT 5.1

February 23, 1998

IDEC Pharmaceuticals Corporation
11011 Torreyana Road
San Diego, CA 92121

Re: IDEC PHARMACEUTICALS CORPORATION
REGISTRATION STATEMENT ON FORM S-3 FOR 2,300,000
SHARES OF COMMON STOCK

Ladies and Gentlemen:

We have acted as counsel to IDEC Pharmaceuticals Corporation,
a Delaware corporation (the "Company"), in connection with the proposed issuance
and sale by the Company of up to Two Million Three Hundred Thousand (2,300,000)
shares of the Company's Common Stock (the "Shares") pursuant to the Company's
Registration Statement on Form S-3 (the "Registration Statement") filed with the
Securities and Exchange Commission under the Securities Act of 1933, as amended
(the "Act").

This opinion is being furnished in accordance with the
requirements of Item 16 of Form S-3 and Item 6-1(b)(5)(i) of Regulation S-K.

We have examined originals or copies of (i) the Amended and
Restated Certificate of Incorporation of the Company; (ii) the Bylaws of the
Company; (iii) certain resolutions of the Board of Directors of the Company; and
(v) such other documents and records as we have deemed necessary and relevant
for the purposes hereof. In addition, we have relied on certificates of officers
of the Company and certificates of public officials as to certain matters of
fact relating to this opinion and have made such investigations of law as we
have deemed necessary and relevant as a basis hereof.

We have assumed the genuineness of all signatures, the
authenticity of all documents, certificates and records submitted to us as
originals, the conformity to authentic original documents, certificates and
records of all such documentation submitted to us as copies and the truthfulness
of all statements of facts contained therein. Based on the foregoing and subject
to the limitations set forth herein and having due regard for such legal
considerations as we deem relevant, we are of the opinion that the Shares, when
issued and sold in the manner described in the Registration Statement, will be
validly issued, fully paid and nonassessable shares of the Common Stock.

<PAGE> 2

IDEC Pharmaceuticals Corporation February 23, 1998
Page 2

We consent to the filing of this opinion letter as Exhibit 5.1
to the Registration Statement and to the reference to this firm under the
caption "Legal Matters" in the prospectus which is part of the Registration
Statement. In giving this consent, we do not thereby admit that we are within
the category of persons whose consent is required under Section 7 of the Act,
the rules and regulations of the Securities and Exchange Commission promulgated
thereunder, or Item 509 of Regulation S-K.

The foregoing opinion is based on and limited to the General
Corporation Law of the State of Delaware and the relevant federal laws of the
United States, and we express no opinion with respect to the laws of any other
jurisdiction.

This opinion letter is rendered as of the date first written
above and we disclaim any obligation to advise you of facts, circumstances,
events or developments which hereafter may be brought to our attention and which
may alter, affect or modify the opinion expressed herein. Our opinion is
expressly limited to the matters set forth above and we render no opinion,
whether by implication or otherwise, as to any other matters relating to the
Company or the Shares.

Very truly yours,

/s/ Brobeck, Phleger & Harrison LLP
-----------------------------------
BROBECK, PHLEGER & HARRISON LLP

<PAGE> 1

EXHIBIT 23.2

[KPMG LETTERHEAD]

INDEPENDENT AUDITORS' CONSENT

The Board of Directors
IDEC Pharmaceuticals Corporation:

We consent to the use of our report included herein and our reports
incorporated herein by reference and to the references to our firm under the
headings "Experts" and "Selected Consolidated Financial Data" in the prospectus.

KPMG PEAT MARWICK LLP

San Diego, California
June 5, 1996
WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
CONDENSED CONSOLIDATED BALANCE SHEETS AND CONDENSED CONSOLIDATED STATEMENTS OF
OPERATIONS CONTAINED IN THE COMPANY'S ANNUAL REPORT ON FORM 10-K FOR THE
YEAR ENDED DECEMBER 31, 1997 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE
TO SUCH FINANCIALS STATEMENTS AND THE NOTES THERETO.
</LEGEND>
<MULTIPLIER> 1,000

<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> DEC-31-1997
<PERIOD START> JAN-01-1997
<PERIOD-END> DEC-31-1997
<CASH> 34,847
<SECURITIES> 34,810
<RECEIVABLES> 3,971
<ALLOWANCES> 0
<INVENTORY> 4,134
<CURRENT-ASSETS> 79,193
<PP&E> 35,933
<DEPRECIATION> 12,484
<TOTAL-ASSETS> 106,013
<CURRENT-LIABILITIES> 19,432
<BONDS> 0
0
0
<COMMON> 19
<OTHER-SE> 179,956
<TOTAL-LIABILITY-AND-EQUITY> 106,013
<SALES> 0
<TOTAL-REVENUES> 44,606
<CGS> 0
<TOTAL-COSTS> 18,875
<OTHER-EXPENSES> 43,727
<LOSS-PROVISION> 0
<INTEREST-EXPENSE> 917
<INCOME-PRETAX> 0
<INCOME-TAX> 0
<INCOME-CONTINUING> 0
<DISCONTINUED> 0
<EXTRAORDINARY> 0
<CHANGES> 0
<NET-INCOME> (15,538)
<EPS-PRIMARY> (0.83)
<EPS-DILUTED> 0

</TABLE>