CONDENSED CONSOLIDATED 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]
Revenue				$ 165
Operating expenses:
Research and development	$ 8,885	$ 2,755	$ 15,724	3,906
General and administrative	3,268	3,190	6,269	4,977
Total operating expenses	12,153	5,945	21,993	8,883
Loss from operations	(12,153)	(5,945)	(21,993)	(8,718)
Total other income, net:
Interest income	166	503	623	619
Other income, net	355	140	399	273
Net loss	$ (11,632)	$ (5,302)	$ (20,971)	$ (7,826)
Net loss per share — basic and diluted	$ (4.43)	$ (5.05)	$ (8.66)	$ (8.49)
Weighted-average common shares outstanding — basic and diluted	2,625,648	1,050,190	2,420,797	921,995
Comprehensive loss:
Net loss	$ (11,632)	$ (5,302)	$ (20,971)	$ (7,826)
Other comprehensive (loss) income, net of tax:
Unrealized (loss) gain on available-for-sale securities	(134)	129	42	129
Total other comprehensive (loss) income	(134)	129	42	129
Comprehensive loss	$ (11,766)	$ (5,173)	$ (20,929)	$ (7,697)