<PAGE> 1
Filed Pursuant to Rule 424(b)(3)
REGISTRATION NO. 333-15819
PROSPECTUS SUPPLEMENT NO. 2 DATED MAY 29, 1997
TO THE PROSPECTUS DATED NOVEMBER 8, 1996 OF IMMUNOGEN, INC.
This Prospectus Supplement No. 2 amends the information in the section
entitled "Selling Stockholders" in the Prospectus dated November 8, 1996, as
amended by Prospectus Supplement No. 1 dated February 21, 1997. Brown Simpson,
LLC ("Brown Simpson") has entered into an agreement with OTA Limited Partnership
("OTA") whereby all 57,500 of the warrants to purchase ImmunoGen, Inc. Common
Stock, $.01 par value per share ("Common Stock"), owned by Brown Simpson have
been transferred to OTA. In order to reflect OTA as a potential Selling
Stockholder hereunder, and assuming for such purposes that the warrants to
purchase all 57,500 shares are exercised, the Selling Stockholder table is
amended by deleting the information as to Brown Simpson as Selling Stockholder
with respect to 57,5000 shares of Common Stock and substituting therefor the
following information:
<TABLE>
<CAPTION>
Shares Owned Prior Shares Owned After
to Offering(1) Offering(2)
---------------------- Number of Shares ---------------------
Selling Stockholder Number Percent Being Offered Number Percent
- ------------------- ------ ------- ---------------- ------ -------
<S> <C> <C> <C> <C> <C>
OTA 120,000 * 57,500 0 --
</TABLE>
- -------------
* Less than 1%.
(1) Based on 19,710,289 shares of Common Stock outstanding on May 27, 1997 and
consists of warrants to purchase 120,000 shares of Common Stock.
(2) Assumes the sale of all shares offered hereby to unaffiliated third parties.
This Prospectus Supplement No. 2 should be read in conjunction with the
Prospectus dated November 8, 1996 and the Prospectus Supplement No. 1 dated
February 21, 1997.
Page 1 of 1 Page
