Exhibit 4.3


 


	
  

  	
  

  William Francis Galvin

  Secretary of
  the Commonwealth

  One Ashburton Place, Boston, Massachusetts 02108-1512

  



 


	
  FORM MUST BE TYPED

  	
   

  	
  Articles
  of Amendment

  	
   

  	
  FORM MUST BE
  TYPED

  



(General Laws Chapter 156D, Section 10.06;
950 CMR 113.34)


 


(1) Exact name of corporation:   ImmunoGen, Inc.    


 


(2) Registered office address:   830 Winter Street, Waltham, MA 02451


(number,
street, city or town, state, zip code)


 


(3) These articles of amendment affect
article(s):  3


(specify
the number(s) of article(s) being amended (I-VI))


 


(4) Date adopted:   November 11,
2009


(month,
day, year)


 


(5) Approved
by:


 


(check appropriate box)


 


o     the incorporators.


 


o     the board of directors without shareholder
approval and shareholder approval was not required.


 


x     the board of directors and the shareholders
in the manner required by law and the articles of organization.


 


(6) State the
article number and the text of the amendment. 
Unless contained in the text of the amendment, state the provisions for
implementing the exchange, reclassification or cancellation of issued shares.


 


 


	
   

  	
   

  
	
  P.C.

  	
   

  



 


 

















 


To
change the number of shares and the par value, * if any, of any type, or to
designate a class or series, of stock, or change a designation of class or
series of stock, which the corporation is authorized to issue, complete the
following:


 


Total
authorized prior to amendment:


 


	
  WITHOUT PAR VALUE

  	
   

  	
  WITH PAR VALUE

  	
   

  
	
  TYPE

  	
   

  	
  NUMBER
  OF SHARES

  	
   

  	
  TYPE

  	
   

  	
  NUMBER OF SHARES

  	
   

  	
  PAR
  VALUE

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
  Common

  	
   

  	
  75,000,000

  	
   

  	
  $

  	
  .01

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
  Preferred

  	
   

  	
  5,000,000

  	
   

  	
  $

  	
  .01

  	
   

  



 


Total
authorized after amendment:


 


	
  WITHOUT PAR VALUE

  	
   

  	
  WITH PAR VALUE

  	
   

  
	
  TYPE

  	
   

  	
  NUMBER
  OF SHARES

  	
   

  	
  TYPE

  	
   

  	
  NUMBER
  OP SHARES

  	
   

  	
  PAR VALUE

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
  Common

  	
   

  	
  100,000,000

  	
   

  	
  $

  	
  .01

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
  Preferred

  	
   

  	
  5,000,000

  	
   

  	
  $

  	
  .01

  	
   

  



 


(7)   The amendment shall be effective at the time
and on the date approved by the Division, unless a later effective date not
more than 90 days from the date and time of filing is specified:


 






*G.L. Chapter 156D eliminates the concept of par value,
however a corporation may specify par value in Article III. See G.L.
Chapter 156D, Section 6.21, and the comments relative thereto.


 

















 


	
  Signed
  by:

  	
  /s/ Daniel M. Junius

  	
   

  	
  ,

  
	
   

  	
  (signature of authorized individual)

  



 


	
  o

  	
  Chairman
  of the board of directors,

  
	
  x

  	
  President,

  
	
  o

  	
  Other
  officer,

  
	
  o

  	
  Court-appointed
  fiduciary,

  



 


on this 16th day of November, 2009.


 

















 


SECRETARY OF THE


COMMONWEALTH


2009 DEC - 1 AM  9:05


MASSACHUSETTS
DIVISION 


 


COMMONWEALTH OF MASSACHUSETTS


 


William Francis Galvin


Secretary of the
Commonwealth


One Ashburton Place,
Boston, Massachusetts 02 108-1512


 


Articles of Amendment


(General Laws Chapter 156D, Section 10.06;
950 CMR 113.34)


 


I  hereby certify that upon examination of these
articles of amendment, it appears that the provisions of the General Laws
relative thereto have been complied with, and the filing fee in the amount of $25,000  having been paid, said articles are
deemed
to have been  filed with me this  1st
day of December, 2009. at time 9:05 a.m./p.m.



 


	
  Effective
  date:

  	
   

  	
   

  
	
   

  	
  (must be within 90 days of date submitted)

  	
   

  



1100574


 


	
   

  	
  /s/ William Francis Galvin

  	
   

  
	
   

  	
  WILLIAM FRANCIS GALVIN

  	
   

  



Secretary
of the Commonwealth


 


Filing
fee: Minimum filing fee $100 per article amended, stock increases $100 per
100,000 shares, plus $100 for each additional 100,000 shares or any fraction
thereof.


 


TO BE FILLED IN BY CORPORATION


Contact
Information:


 


Craig Barrows


ImmunoGen,
Inc.


830 Winter Street, Waltham, MA 02451


Telephone:  (781) 895-0600


Email:  craig.barrows@immunogen.com


 


Upon
filing, a copy of this filing will be available at www.sec.state.ma.us/cor. If
the document is rejected, a copy of the rejection sheet and rejected document
will be available in the rejected queue.


 


	
  /s/
  [ILLEGIBLE]

  	
   

  	
   

  
	
  Examiner

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
  /s/
  [ILLEGIBLE]

  	
   

  	
   

  
	
  Name
  approval

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
  C

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
  M