Statement of Changes in Beneficial Ownership (4)

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

OMB APPROVAL

OMB Number:

3235-0287

Estimated average burden
hours per response...

0.5

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 * MITCHELL DEAN J	2. Issuer Name and Ticker or Trading Symbol ImmunoGen, Inc. [ IMGN ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director                    _____ 10% Owner _____ Officer (give title below)    _____ Other (specify below)
(Last)          (First)          (Middle) C/O IMMUNOGEN, INC., 830 WINTER STREET	3. Date of Earliest Transaction (MM/DD/YYYY) 9/3/2021
(Street) WALTHAM, MA 02451 (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	9/3/2021		M		5000	A	$1.84	15000	D
Common Stock	9/3/2021		M		10000	A	$4.64	25000	D
Common Stock	9/3/2021		M		18000	A	$2.10	43000	D
Common Stock	9/3/2021		M		50000	A	$4.56	93000	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
Stock Option (right to buy)	$1.84	9/3/2021		M			5000	3/1/2017 (1)	12/9/2026	Common Stock	5000	$1.84	0	D
Stock Option (right to buy)	$4.64	9/3/2021		M			10000	9/1/2017 (2)	6/13/2027	Common Stock	10000	$4.64	0	D
Stock Option (right to buy)	$2.10	9/3/2021		M			18000	9/1/2019 (3)	6/20/2029	Common Stock	18000	$2.10	0	D
Stock Option (right to buy)	$4.56	9/3/2021		M			50000	9/1/2020 (4)	6/17/2030	Common Stock	50000	$4.56	0	D

Explanation of Responses:
(1)	Exercisable as to 2,500 shares on each of 3/1/17 and 6/1/17, contingent upon the individual remaining a director as of each vesting date.
(2)	Exercisable as to 2,500 shares on each of 9/1/17, 12/1/17, 3/1/18, and 6/1/18, contingent upon the individual remaining a director as of each vesting date.
(3)	Exercisable as to 4,500 shares on each of 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.
(4)	Exercisable as to 12,500 shares on each of 9/1/20, 12/1/20, 3/1/21, and 6/1/21, contingent upon the individual remaining a director as of each vesting date.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
MITCHELL DEAN J C/O IMMUNOGEN, INC. 830 WINTER STREET WALTHAM, MA 02451	X

Signatures
/s/ Joseph J. Kenny, attorney in fact		9/3/2021
**Signature of Reporting Person		Date