Condensed Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue:
Total revenue	$ 4,382
Operating expenses:
Research and development	23,608	$ 13,427
General and administrative	3,908	3,697
Total operating expenses	27,516	17,124
Operating loss	(23,134)	(17,124)
Other income	1,089	311
Loss before benefit from income taxes	(22,045)	(16,813)
Benefit from income taxes	85	46
Net loss	$ (21,960)	$ (16,767)
Net loss per share:
Basic and Diluted	$ (0.56)	$ (0.51)
Weighted average shares:
Basic and Diluted	39,552,277	32,681,661
Other comprehensive income (loss), net of tax of $0:
Change in unrealized gains (losses) on available-for- sale marketable securities	$ 187	$ (44)
Total comprehensive loss	(21,773)	$ (16,811)
License and Milestone Fees [Member]
Revenue:
Total revenue	4,242
Clinical Compound Revenue [Member]
Revenue:
Total revenue	$ 140