EXPLANATORY NOTE
This registration statement is being filed solely for the purpose of registering 3,821,900 additional shares of common stock, par value $.01 per share (the Common Stock), of ImmunoGen, Inc. (the Company) to be offered to participants under the Companys 2006 Employee, Director and Consultant Equity Incentive Plan, as amended and restated (the 2006 Plan), originally adopted in 2006. The maximum number of shares of Common Stock reserved and available for issuance under the 2006 Plan includes 2,500,000 shares, which were previously registered with the Securities and Exchange Commission (the Commission) on Form S-8 (File No. 333-138713) filed on November 15, 2006 (the 2006 Registration Statement), an additional 2,000,000 shares which the Companys shareholders authorized for issuance under the 2006 Plan on November 12, 2008, which were previously registered with the Commission on Form S-8 (File No. 333-155540) filed on November 21, 2008 (the 2008 Registration Statement), an additional 4,000,000 shares which the Companys shareholders authorized for issuance under the 2006 Plan on November 16, 2010, which were previously registered with the Commission on Form S-8 (File No. 333-170788) filed on November 23, 2010 (the 2010 Registration Statement) and an additional 3,500,000 shares which the Companys shareholders authorized for issuance under the 2006 Plan on November 13, 2012 (which shares are included in this registration statement), plus the number of shares underlying any grants previously made under the Companys Restated Stock Option Plan (the Restated Stock Option Plan) that are forfeited, canceled or are terminated (other than by exercise) from and after November 11, 2006. An aggregate of 1,674,997 additional shares have been included in the shares reserved for issuance under the 2006 Plan as a result of the forfeiture, cancellation or termination (other than by exercise), during the period between November 11, 2006 and October 31, 2012, of grants previously made under the Restated Stock Option Plan, of which 811,245 shares were previously registered with the Commission on Form S-8 (File No. 333-147738) filed with the Commission on November 30, 2007, 185,444 shares were previously registered with the Commission on the 2008 Registration Statement, 356,408 shares were previously registered with the Commission on the 2010 Registration Statement, and 321,900 shares are included in this registration statement.
Pursuant to General Instruction E of Form S-8, the contents of the 2006 Registration Statement are incorporated herein by reference, except as otherwise noted below.
PART II
INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.
The following documents are incorporated herein by reference:
(a)
The Companys annual report on Form 10-K for the fiscal year ended June 30, 2012, filed with the Commission on August 29, 2012;
(b)
The Companys amendment no. 1 to quarterly report on Form 10-Q/A for the fiscal quarter ended March 31, 2012, filed with the Commission on October 10, 2012;
(c)
The Companys quarterly report on Form 10-Q for the fiscal quarter ended September 30, 2012, filed with the Commission on October 31, 2012;
(d)
The Companys current reports on Form 8-K filed with the Commission on July 12, October 26 (excluding the information and exhibit furnished pursuant to Item 2.02) and November 16, 2012; and
(e)
The description of the Companys common stock contained in the Companys registration statement on Form 8-A, filed with the Commission on September 25, 1989, as amended by Amendment No. 1 thereto, filed with the Commission on November 15, 1989, pursuant to Section 12 of the Securities Exchange Act of 1934, as amended (the Exchange Act), including any amendment thereto or report filed for the purpose of updating such description.
All documents subsequently filed by the Company pursuant to Section 13(a), 13(c), 14 and 15(d) of the Exchange Act, prior to the filing of a post-effective amendment which indicates that all securities offered hereby
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