Condensed Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue:
Total revenue		$ 5,634	$ 1,935	$ 13,727
Operating expenses:
Research and development	$ 25,225	26,108	44,356	59,644
General and administrative	5,651	5,410	12,016	9,968
Total operating expenses	30,876	31,518	56,372	69,612
Operating loss	(30,876)	(25,884)	(54,437)	(55,885)
Other income, net	131	634	391	1,591
Loss before benefit from income taxes	(30,745)	(25,250)	(54,046)	(54,294)
Benefit from income taxes	0	182	0	304
Net Loss	$ (30,745)	$ (25,068)	$ (54,046)	$ (53,990)
Net Loss per share:
Basic and Diluted	$ (0.61)	$ (0.54)	$ (1.08)	$ (1.15)
Weighted average shares:
Basic and Diluted	50,059,984	46,799,703	49,989,379	46,762,327
Other comprehensive income (loss), net of tax of $0:
Change in unrealized gains (losses) on available-for-sale marketable securities	$ (17)	$ 703	$ (78)	$ 465
Total comprehensive loss	$ (30,762)	(24,365)	(54,124)	(53,525)
License and Milestone Fees
Revenue:
Total revenue		5,099	1,192	13,120
Collaborative Revenue
Revenue:
Total revenue			706
Clinical Compound Revenue
Revenue:
Total revenue		$ 535	$ 37	$ 607