X0306 4 2021-06-30 0 0000855654 ImmunoGen, Inc. IMGN 0001838777 Lentini Renee C/O IMMUNOGEN, INC. 830 WINTER STREET WALTHAM MA 02451 0 1 0 0 V.P.-Fin., Prin. Acctg. Off. Common Stock 2021-06-30 4 A 0 1683 5.52 A 13831 D These shares were purchased due to participation by the reporting individual in the ImmunoGen Employee Stock Purchase Plan (the ESPP). It pertains to the ESPP purchase period from January 1, 2021 through June 30, 2021. In accordance with the ESPP, these shares were purchased based on 85% of the closing price of the issuer's common stock on January 4, 2021. /s/ Renee Lentini 2021-07-02