Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenue:
Product revenue	$ 151		$ 588	$ 10
Research revenue	839	$ 564	1,498	743
Total revenue	990	564	2,086	753
Costs and expenses:
Cost of product revenue	1,781		2,807	3
Research and development	6,369	6,651	12,958	12,520
Selling, general and administrative	6,143	4,437	12,347	8,905
Total costs and expenses	14,293	11,088	28,112	21,428
Loss from operations	(13,303)	(10,524)	(26,026)	(20,675)
Interest expense, net	(805)	(477)	(1,540)	(954)
Other income, net	62	6	94	15
Net loss and comprehensive loss	$ (14,046)	$ (10,995)	$ (27,472)	$ (21,614)
Net loss per share — basic and diluted	$ (0.58)	$ (0.54)	$ (1.13)	$ (1.07)
Weighted-average number of common shares used in computing net loss per share — basic and diluted	24,321,310	20,260,591	24,270,041	20,171,051