1 Exhibit 3.3 [COMMONWEALTH OF MASSACHUSETTS LETTERHEAD] FEDERAL IDENTIFICATION No. 04 2726691 ARTICLES OF AMENDMENT GENERAL LAWS, CHAPTER 156B, SECTION 72 We Mitchel Sayare, President and Jonathan L. Kravetz Clerk/of ImmunocGen, Inc. - ------------------------------------------------------------------------------- (EXACT Name of Corporation) located at: 128 Sidney Street, Cambridge, MA 02139 ------------------------------------------------------------------- (MASSACHUSETTS Address of Corporation) do hereby certify that these ARTICLES OF AMENDMENT affecting Articles NUMBERED: 3 - ------------------------------------------------------------------------------- (Number those articles 1, 2, 3, 4, 5 and/or 6 being amended hereby) of the Articles of Organization were duly adopted at a meeting held on June 6, 1996, by vote of: 12,583,631 shares of Common out of 15,530,355 shares outstanding, - ---------- --------------------- ---------- type, class & series, (if any) shares of out of shares outstanding, - ---------- --------------------- ----------- type, class & series, (if any) shares of out of shares outstanding, - ---------- --------------------- ---------- type, class & series, (if any) CROSS OUT being at least a majority of each type, class or series outstanding INAPPLI- and entitled to vote thereon- CABLE CLAUSE C / / P / / M / / 1 For amendments adopted pursuant to Chapter 156B, Section 70. R.A. / / 2 For amendments adopted pursuant to Chapter 156B, Section 71. Note: if the space provided under any Amendment or item on this form is insufficient, additions shall be set forth on separate 8-1/2 x 11 sheets of paper leaving a left-hand margin of at least 1 inch for binding. Additions to more than one Amendment may be continued on a single sheet so long as each Amendment requiring each such addition is clearly indicated. 2 To CHANGE the number of shares and the par value (if any) of any type, class or series of stock which the corporation is authorized to issue, fill in the following: The total presently authorized is: WITHOUT PAR VALUE STOCKS TYPE NUMBER OF SHARES COMMON:..................................... PREFERRED:.................................. WITH PAR VALUE STOCKS TYPE NUMBER OF SHARES PAR VALUE COMMON:..................................... 20,000,000 $.01 PREFERRED: Series A......................... None Series B......................... None Series C......................... 122,555 $.01 Series D......................... 154,525 $.01 CHANGE the total authorized to: WITHOUT PAR VALUE STOCKS TYPE NUMBER OF SHARES COMMON:..................................... PREFERRED:.................................. WITH PAR VALUE STOCKS TYPE NUMBER OF SHARES PAR VALUE COMMON:..................................... 30,000,000 $.01 PREFERRED: Series A......................... None Series B......................... None Series C......................... 122,555 $.01 Series D......................... 154,525 $.01 3 The foregoing amendment will become effective when these articles of amendment are filed in accordance with Chapter 156B, Section 6 of The General Laws unless these articles specify, in accordance with the vote adopting the amendment, a later effective date not more than thirty days after such filing, in which event the amendment will become effective on such later date. LATER EFFECTIVE DATE: _________________________ IN WITNESS WHEREOF AND UNDER THE PENALTIES OF PERJURY, we have hereunto signed our names this sixth day of June , in the year 1996. /s/ Mitchel Sayare President _________________________________________________________ Mitchel Sayare /s/ Jonathan L. Kravetz Clerk _________________________________________________________ Jonathan L. Kravetz 4 THE COMMONWEALTH OF MASSACHUSETTS ARTICLES OF AMENDMENT GENERAL LAWS, CHAPTER 156B, SECTION 72 ______________________________________ ______________________________________ I hereby approve the within articles of amendment and, the filing fee in the amount of $______ having been paid, said articles are deemed to have been filed with me this ____ day of _____________, 19__. MICHAEL J. CONNOLLY Secretary of State To be filled in by Corporation PHOTOCOPY OF ARTICLES OF AMENDMENT TO BE SENT TO: Anne T. Leland, Legal Assistant ______________________________________________________ Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. ______________________________________________________ One Financial Center, Boston, MA 02111 ______________________________________________________ 617 542 6000 Telephone: ___________________________________