Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues:
Total revenues	$ 3,013	$ 172	$ 3,031	$ 2,522
Cost of revenue	600	2	600	466
Gross profit	2,413	170	2,431	2,056
Operating expenses:
Research and development	17,580	17,941	57,436	47,337
General and administrative	6,922	5,961	17,410	18,290
Total operating expenses	24,502	23,902	74,846	65,627
Loss from operations	(22,089)	(23,732)	(72,415)	(63,571)
Interest expense	(1,443)	(1,404)	(4,328)	(2,096)
Other income (expense), net	294	1,010	1,896	2,237
Loss before provision for income taxes	(23,238)	(24,126)	(74,847)	(63,430)
Provision for income taxes	301		303	6
Net loss	$ (23,539)	$ (24,126)	$ (75,150)	$ (63,436)
Net loss per common share, basic and diluted	$ (0.37)	$ (0.39)	$ (1.20)	$ (1.17)
Shares used in computing net loss per share - basic and diluted	62,828,513	62,071,397	62,676,591	54,204,907
Comprehensive loss:
Net loss	$ (23,539)	$ (24,126)	$ (75,150)	$ (63,436)
Unrealized (loss) gain on available-for-sale securities, net of tax	(12)	19	42	30
Comprehensive loss	(23,551)	(24,107)	(75,108)	(63,406)
Licensing
Revenues:
Total revenues	3,000		3,000	2,320
Other
Revenues:
Total revenue	$ 13	$ 172	$ 31	$ 202