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
Operating expenses:
Research and development	$ 13,885	$ 1,253	$ 23,908	$ 9,899
General and administrative	2,424	474	5,522	911
Total operating expenses	16,309	1,727	29,430	10,810
Loss from operations	(16,309)	(1,727)	(29,430)	(10,810)
Other income (expense), net:
Change in fair value of preferred stock tranche obligation		(8,400)		(8,400)
Change in fair value of anti-dilution right liability		(1,021)		(1,032)
Other income, net	755		1,286
Total other income (expense), net	755	(9,421)	1,286	(9,432)
Net loss and comprehensive loss	(15,554)	(11,148)	(28,144)	(20,242)
Accretion of redeemable convertible preferred stock to redemption value		(251)		(321)
Net loss attributable to common stockholders	$ (15,554)	$ (11,399)	$ (28,144)	$ (20,563)
Net loss per share attributable to common stockholders - basic and diluted	$ (0.56)	$ (89.66)	$ (2.66)	$ (236.67)
Weighted-average number of shares used in computing net loss per share attributable to common stockholders, basic and diluted	28,024,779	127,141	10,589,119	86,884