CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating expenses:
Research and development	$ 59,718	$ 60,425
General and administrative	21,420	18,276
Total operating expenses	81,138	78,701
Loss from operations	(81,138)	(78,701)
Other income (expense), net
Interest income	1,401	1,792
Other expense	(39)	(25)
Total other income (expense), net	1,362	1,767
Net loss	(79,776)	(76,934)
Accretion of redeemable convertible preferred stock to redemption value	0	(6,371)
Net loss attributable to common stockholders	$ (79,776)	$ (83,305)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (2.86)	$ (5.54)
Weighted average common shares outstanding, basic and diluted (in shares)	27,878,701	15,036,397
Comprehensive loss:
Net loss	$ (79,776)	$ (76,934)
Other comprehensive loss:
Unrealized gains (losses) on marketable securities	75	(62)
Total other comprehensive income (loss)	75	(62)
Comprehensive loss	$ (79,701)	$ (76,996)