X0306 4 2019-06-20 0 0000855654 IMMUNOGEN INC IMGN 0001557290 Arbuckle Stuart A C/O VERTEX PHARMACEUTICALS INCORPORATED 50 NORTHERN AVE BOSTON MA 02210 1 0 0 0 Deferred Share Unit 0 2019-06-20 4 A 0 4000 0 A 2019-09-01 Common Stock 4000 16000 D Stock Option (right to buy) 2.10 2019-06-20 4 A 0 18000 2.1 A 2019-09-01 2029-06-20 Common Stock 18000 18000 D The deferred share units were issued pursuant to the Issuer's Compensation Policy for Non-Employee Directors and are convertible into Common Stock on a one-to-one basis. The vested deferred share units are to be settled 100% in shares of Common Stock of the Company upon the reporting person's retirement from the Board of Directors. The deferred share units vest quarterly on 9/1/19, 12/1/19, 3/1/20 and 6/1/20, contingent upon the individual remaining a director as of each vesting date. Exercisable as to 4,500 shares on 9/1/19, 12/1/19, 3/1/20 and 6/1/20, contingent upon the individual remaining a director as of each vesting date. /s/ Craig Barrows, attorney in fact 2019-06-24