EXHIBIT 10.1

[ * ] = Certain confidential information contained in this document, marked by brackets, has been omitted and filed separately with the Securities and Exchange Commission pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended.

SECOND AMENDMENT TO DRUG DISCOVERY COLLABORATION AGREEMENT

THIS AMENDMENT NO. 2 (“Second Amendment”), effective as of October 1, 2005 (Amendment Date”), is entered into by and between Genentech, Inc., a Delaware corporation, having a principal place of business at 1 DNA Way, South San Francisco, California 94080 (“Genentech”) and Array BioPharma Inc., a Delaware corporation, having a principal place of business at 3200 Walnut Street, Boulder, Colorado 80301 (“Array”) (collectively, the “Parties” or individually, a “Party”).

WHEREAS, Genentech and Array entered into a Drug Discovery Collaboration Agreement, effective as of December 22, 2003, which was subsequently modified by a Letter Agreement, dated October 11, 2004, and amended by a First Amendment, dated May 20, 2005 (collectively, the “Agreement”).

WHEREAS, the Parties desire to amend the Agreement as set forth below.

NOW, THEREFORE, the Parties agree as follows:

1.                This Second Amendment hereby amends and revises the Agreement to incorporate the terms and conditions set forth in this Second Amendment.  The relationship of the Parties shall continue to be governed by the terms of the Agreement, as amended.

2.                All capitalized terms used in this Second Amendment shall have the meanings defined in the Agreement unless otherwise defined herein.

3.