1 Exhibit 10.4 THIS WARRANT AND THE SHARES ISSUABLE UPON THE EXERCISE OF THIS WARRANT HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED. EXCEPT AS OTHERWISE SET FORTH HEREIN OR IN A SECURITIES PURCHASE AGREEMENT DATED AS OF MARCH...Letter Agreement • November 14th, 1997 • Immunogen Inc • Pharmaceutical preparations • Massachusetts
