Ownership Submission
FORM 3
 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
  ZIFF ASSET MANAGEMENT LP
 2. Date of Event Requiring Statement (Month/Day/Year)
06/20/2008		 3. Issuer Name and Ticker or Trading Symbol
IMMUNOGEN INC [IMGN]
(Last)
(First)
(Middle)
283 GREENWICH AVE		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

GREENWICH, CT 06830		 6. Individual or Joint/Group Filing(Check Applicable Line)
___ Form filed by One Reporting Person
_X_ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security
(Instr. 4)		 2. Amount of Securities Beneficially Owned
(Instr. 4)		 3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)		 4. Nature of Indirect Beneficial Ownership
(Instr. 5)
Common Stock 9,046,200
D (1) (2)
 

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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)		 2. Date Exercisable and Expiration Date
(Month/Day/Year)		 3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)		 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)		 6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
ZIFF ASSET MANAGEMENT LP
283 GREENWICH AVE
GREENWICH, CT 06830		     X    
PBK HOLDINGS INC
283 GREENWICH AVE
GREENWICH, CT 06830		     X    
KORSANT PHILIP B
283 GREENWICH AVE
GREENWICH, CT 06830		     X    
ZBI Equities, L.L.C.
283 GREENWICH AVE
GREENWICH, CT 06830		     X    

Signatures

/s/ David Gray, Vice President of PBK Holdings, Inc., the general partner of Ziff Asset Management, L.P. 06/30/2008
**Signature of Reporting Person Date
/s/ David Gray, Vice President of PBK Holdings, Inc. 06/30/2008
**Signature of Reporting Person Date
/s/ Philip B. Korsant 06/30/2008
**Signature of Reporting Person Date
/s/ David Gray, Vice President of PBK Holdings, Inc., sole member of ZBI Equities, L.L.C. 06/30/2008
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) This statement is being filed by Ziff Asset Management, L.P. ("Ziff Asset Management"), PBK Holdings, Inc. ("PBK Holdings"), Philip B. Korsant ("Korsant") and ZBI Equities, L.L.C. ("ZBI Equities" and collectively with Ziff Asset Management, PBK Holdings and Korsant, the "Reporting Persons."). PBK Holdings is the general partner of Ziff Asset Management, Korsant is the sole shareholder of PBK Holdings and ZBI Equities assists in the management of certain assets held by Ziff Asset Management.
(2) Ziff Asset Management is the record owner of all of the 9,046,200 shares of common stock, par value $.01 per share of ImmunoGen, Inc. (the "Common Stock") reported herein. The Reporting Persons do not have or share voting or investment power over 1,233,700 shares of the Common Stock reported herein and each of the Reporting Persons disclaims beneficial ownership of such 1,233,700 shares, except to the extent of its respective pecuniary interests, if any, in such shares. PBK Holdings, Korsant and ZBI Equities may each be deemed to have or share voting or investment power over the remaining 7,812,500 shares of Common Stock reported herein. Each of the Reporting Persons disclaims beneficial ownership of such 7,812,500 shares of Common Stock, except to the extent of its respective pecuniary interest, if any, in such 7,812,500 shares.

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