Condensed Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Research and development (includes related party expense (benefit) of $(129) and $(30) for the three months ended June 30, 2020 and 2019, respectively, and $(371) and $64 for the six months ended June 30, 2020 and 2019, respectively)	$ 17,924	$ 12,497	$ 35,499	$ 21,046
General and administrative (includes related party expense of $372 and $74 for the three months ended June 30, 2020 and 2019, respectively and $658 and $153 for the six months ended June 30, 2020 and 2019, respectively)	10,317	2,297	15,628	6,332
Total operating expenses	28,241	14,794	51,127	27,378
Loss from operations	(28,241)	(14,794)	(51,127)	(27,378)
Interest expense	(604)		(1,122)
Other income (expense), net	(4)	741	576	1,592
Net and comprehensive loss	$ (28,849)	$ (14,053)	$ (51,673)	$ (25,786)
Net loss per share - basic and diluted	$ (0.75)	$ (0.39)	$ (1.35)	$ (0.71)
Weighted-average shares used in computing net loss per share - basic and diluted	38,291,414	36,309,740	38,150,520	36,242,814