CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue:
License revenue	$ 0	$ 425
Total revenue	0	425
Operating expenses:
Research and development	3,255	2,874
General and administrative	1,952	2,213
(Gain) Loss from change in fair value of contingent consideration	(1,200)	1,500
Total operating expenses	4,007	6,587
Loss from operations	(4,007)	(6,162)
Other income:
Other income, net	44	101
Total other income, net	44	101
Net loss and comprehensive loss	$ (3,963)	$ (6,061)
Net loss per share — basic and diluted (in dollars per share)	$ (0.11)	$ (0.25)
Weighted-average number of common shares used in net loss per share- basic and diluted (in shares)	35,674	24,610