Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Total revenues	$ 172		$ 2,522
Cost of revenue	2		466
Gross profit	170		2,056
Operating expenses:
Research and development	17,941	$ 15,365	47,337	$ 58,325
General and administrative	5,961	5,860	18,290	17,752
Total operating expenses	23,902	21,225	65,627	76,077
Loss from operations	(23,732)	(21,225)	(63,571)	(76,077)
Other (expense) income, net	(394)	501	141	1,624
Loss before provision for income taxes	(24,126)	(20,724)	(63,430)	(74,453)
Provision for income taxes			6
Net loss	$ (24,126)	$ (20,724)	$ (63,436)	$ (74,453)
Net loss per common share, basic and diluted	$ (0.39)	$ (0.44)	$ (1.17)	$ (1.57)
Shares used in computing net loss per share - basic and diluted	62,071,397	47,464,310	54,204,907	47,404,039
Comprehensive loss:
Net loss	$ (24,126)	$ (20,724)	$ (63,436)	$ (74,453)
Unrealized (loss) gain on available-for-sale securities, net of tax	19	30	30	61
Comprehensive loss	(24,107)	$ (20,694)	(63,406)	$ (74,392)
Licensing
Revenues:
Total revenues			2,320
Other
Revenues:
Total revenues	$ 172		$ 202