EXHIBIT 99.1

AGREEMENT

In accordance with Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree that this Statement on Schedule 13D relating to the Common Stock, $0.00000002 par value, of MEI Pharma, Inc. is being filed with the Securities and Exchange Commission on behalf of each of them.

March 5, 2013

BAKER BROS. ADVISORS, LLC
By:	/s/ Scott L. Lessing
	Name: Scott L. Lessing Title: President

/s/ Julian C. Baker

Julian C. Baker

/s/ Felix J. Baker

Felix J. Baker