[*CONFIDENTIAL TREATMENT HAS BEEN REQUESTED AS TO CERTAIN PORTIONS OF THIS
DOCUMENT. EACH SUCH PORTION, WHICH HAS BEEN OMITTED HEREIN AND REPLACED
WITH AN ASTERISK [*], HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND
AVANT IMMUNOTHERAPEUTICS, INC.
COMMON STOCK PURCHASE AGREEMENT
THIS COMMON STOCK PURCHASE AGREEMENT (the “ Agreement ”) is made as of
May , 2008, by and between AVANT IMMUNOTHERAPEUTICS, INC. , a Delaware corporation (the
“ Company ”) and PFIZER VACCINES LLC , a Delaware limited liability company (“ Pfizer ”).
WHEREAS, the Company desires to issue, and Pfizer desires to acquire, stock of the Company as
herein described, on the terms and conditions hereinafter set forth;
NOW, THEREFORE, IT IS AGREED between the parties as follows:
1. Purchase and Sale of Stock. Pfizer hereby agrees to purchase from the Company, and the
Company hereby agrees to sell to Pfizer, an aggregate of 781,250 shares of the Common Stock of the Company
(the “ Shares ”) at $12.80 per share, for an aggregate purchase price of $10,000,000.00, payable in cash. The
closing hereunder, including payment for and delivery of the Shares shall occur at the offices of the Company
immediately following the execution of this Agreement, or at such other time and place as the parties may mutually
2. Limitations on Transfer. Pfizer shall not assign, hypothecate, donate, encumber or otherwise
dispose of any interest in the Shares except in compliance with the provisions herein and applicable securities
laws. The Company shall not be required (a) to transfer on its books any of the Shares which shall have been
transferred in violation of any of the provisions set forth in this Agreement or (b) to treat as owner of such shares
or to accord the right to vote as such owner or to pay dividends to any transferee to whom such shares shall have
been so transferred.