Item 1.01. Entry Into a Material Definitive Agreement.

     Amended and Restated Collaboration Agreements

     On November 28, 2007, Regeneron Pharmaceuticals, Inc. (the "Company") entered into a global, strategic collaboration with various affiliates of sanofi-aventis, a company organized under the laws of France (sanofi-aventis and its affiliates are referred to herein as "Sanofi"), to discover, develop and commercialize fully-human therapeutic antibodies utilizing the Company's VelociSuite of technologies (the "Collaboration"). The Collaboration has been governed by a Discovery and Preclinical Agreement, dated November 28, 2007 (the "Discovery Agreement"), by and between Aventis Pharmaceuticals Inc. and the Company, and a License and Collaboration Agreement, dated November 28, 2007, by and among Aventis Pharmaceuticals Inc., sanofi-aventis Amérique du Nord and the Company (the "License and Collaboration Agreement" and, together with the Discovery Agreement, the "Original Collaboration Agreements").

     On November 10, 2009, the Company and Sanofi amended the Original Collaboration Agreements by entering into an Amended and Restated Discovery and Preclinical Agreement (the “Amended and Restated Discovery Agreement”) and an Amended and Restated License and Collaboration Agreement (the “Amended and Restated License Agreement”). The material amendments to the Original Collaboration Agreements are as follows: (i) the funded program for Regeneron to identify and validate potential drug discovery targets and develop fully-human therapeutic antibodies against such targets (the "Discovery Program") was extended by an additional five years to end on December 31, 2017, subject to an option for Sanofi to extend certain antibody development and preclinical activities under the Discovery Program for up to three additional years; (ii) the maximum annual amount reimbursed by Sanofi under the Discovery Program was increased from $100 million per year to $160 million per year, subject to a one-time option for Sanofi to adjust the maximum reimbursement amount down to $120 million per year commencing in 2014 if over the prior two years certain specified criteria are not satisfied; (iii) the exclusivity provisions in the Original Collaboration Agreements were amended to give Sanofi additional flexibility to license and develop antibodies outside the collaboration; (iv) under certain conditions the Company will be entitled to receive a $10 million milestone payment for each antibody product candidate licensed by Sanofi from the Discovery Program to the extent it was derived using new antibody technologies developed by the Company; and (v) Sanofi agreed to reimburse up to $30 million of costs to expand the Company’s antibody manufacturing facilities in Rensselaer, New York.