Exhibit 1
Joint Filing Agreement
The undersigned hereby agree that a single Schedule 13G (or any amendment thereto) relating to the common stock of the Issuer shall be filed on behalf of each of the undersigned and that this Agreement shall be filed as an exhibit to such Schedule 13G.
Dated: April 1, 2015
| AMGEN INC. | ||
| By: | /s/ David J. Scott | |
| Name: | David J. Scott | |
| Title: | Senior Vice President, General Counsel and Secretary | |
| AMGEN INVESTMENTS LTD. | ||
| By: | /s/ David J. Scott | |
| Name: | David J. Scott | |
| Title: | Senior Vice President and Assistant Secretary | |