Loxo Oncology (LOXO) SC 13D/A Loxo Oncology, Inc.

EXHIBIT 1

JOINT FILING AGREEMENT

The undersigned hereby agree that the Statement on this Schedule 13D, dated November 19, 2015 (the “Schedule 13D”), with respect to the Common Stock, of Loxo Oncology, Inc. is filed, and all amendments thereto will be filed, on behalf of each of us pursuant to and in accordance with the provisions of Rule 13d-1(k) under the Securities and Exchange Act of 1934, as amended, and that this Agreement shall be included as an Exhibit to this Schedule 13D.  Each of the undersigned agrees to be responsible for the timely filing of the Schedule 13D, and for the completeness and accuracy of the information concerning itself contained therein.  This Agreement may be executed in any number of counterparts, all of which taken together shall constitute one and the same instrument.

IN WITNESS WHEREOF, the undersigned have executed this Agreement as of the 19th day of November, 2015.

OrbiMed Advisors LLC a Delaware Limited Liability Company
By:	/s/ Samuel D. Isaly
	Name:	Samuel D. Isaly
	Title:	Managing Member
OrbiMed Capital GP V LLC a Delaware Limited Liability Company
By:	OrbiMed Advisors LLC A Delaware Limited Liability Company and its Managing Member
By:	/s/ Samuel D. Isaly
	Name:	Samuel D. Isaly
	Title:	Managing Member
Samuel D. Isaly
By:	/s/ Samuel D. Isaly
	Samuel D. Isaly