CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenue:
Collaboration revenue	$ 0	$ 229
License revenue	425	0
Total revenue	425	229
Operating expenses:
Research and development	2,874	4,632
General and administrative	2,213	2,147
Loss from change in fair value of contingent consideration	1,500	0
Total operating expenses	6,587	6,779
Loss from operations	(6,162)	(6,550)
Other income (expense):
Other income, net	101	138
Loss on extinguishment of debt	0	(915)
Interest expense	0	(247)
Total other income (expense), net	101	(1,024)
Net loss and comprehensive loss	$ (6,061)	$ (7,574)
Net loss per share — basic and diluted (in dollars per share)	$ (0.25)	$ (0.39)
Weighted-average number of common shares used in net loss per share — basic and diluted	24,610	19,639