JOINT FILING AGREEMENT

The undersigned acknowledge and agree that the foregoing statement on Schedule 13G is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on Schedule 13G may be filed on behalf of each of the undersigned without the necessity of filing additional joint filing agreements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him or it contained herein and therein, but shall not be responsible for the completeness and accuracy of the information concerning the others, except to the extent that he or it knows or has reason to believe that such information is inaccurate.

MERCK SHARP & DOHME RESEARCH GMBH /s/ Katie Fedosz	02/12/2016
Katie Fedosz, as Attorney-in-Fact	Date
MERCK SHARP & DOHME CORP. /s/ Katie Fedosz	02/12/2016
Katie Fedosz, as Assistant Secretary	Date
MERCK & CO., INC. /s/ Katie Fedosz	02/12/2016
Katie Fedosz, as Senior Assistant Secretary	Date