FORM 4 [ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).         
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES
                                                                                  
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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940
                       
1. Name and Address of Reporting Person * FOSTER DAVID G 2. Issuer Name and Ticker or Trading Symbol ImmunoGen, Inc. [ IMGN ] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable)_____ Director                    _____ 10% Owner
__X__ Officer (give title below)    _____ Other (specify below)
V.P.-Fin., Prin. Acctg. Off.
(Last)         (First)         (Middle)
22 HILLSIDE DR.		 3. Date of Earliest Transaction (MM/DD/YYYY)
12/31/2020
(Street)
TOWNSEND, MA 01469
(City)       (State)       (Zip)
 4. If Amendment, Date Original Filed (MM/DD/YYYY)
 
 6. Individual or Joint/Group Filing (Check Applicable Line) _X _ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)		 2. Trans. Date 2A. Deemed Execution Date, if any 3. Trans. Code
(Instr. 8)		 4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)		 5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)		 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V Amount (A) or (D) Price
Common Stock  12/31/2020    M    27240  A  (3) 48964  D   
Common Stock  12/31/2020    S    11052 (5) D $6.38 (4) 37912  D   

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security
(Instr. 3)		 2. Conversion or Exercise Price of Derivative Security 3. Trans. Date 3A. Deemed Execution Date, if any 4. Trans. Code
(Instr. 8)		 5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)		 6. Date Exercisable and Expiration Date 7. Title and Amount of Securities Underlying Derivative Security
(Instr. 3 and 4)		 8. Price of Derivative Security
(Instr. 5)		 9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Restricted Share Unit  $0 (1) 12/31/2020    M        27240    (2)  (2) Common Stock  27240  $0 (1) 0  D   

Explanation of Responses:
(1)  Each restricted stock unit ("RSU") represents the contingent right to receive, upon vesting of the RSU, one share of the Issuer's common stock.
(2)  On April 1, 2019, the reporting person was granted 45,400 restricted share units, vesting 40% on April 1, 2020 and 60% on December 31, 2020, subject to continued service through each such vesting date.
(3)  Restricted stock units convert into common stock on a one-for-one basis
(4)  The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.27 to $6.50, inclusive. The reporting person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within these ranges.
(5)  Represents the number of shares sold by the reporting person to cover tax withholding obligations in connection with the vesting of the RSU's listed in Table II per a 10b5-1 plan.

Reporting Owners
Reporting Owner Name / Address
Relationships
Director 10% Owner Officer Other
FOSTER DAVID G
22 HILLSIDE DR.
TOWNSEND, MA 01469

V.P.-Fin., Prin. Acctg. Off.

Signatures
/s/ David G. Foster 1/4/2021
**Signature of Reporting Person Date