Unaudited Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating expenses:
Research and development	$ 6,217	$ 7,647	$ 19,973	$ 19,497
General and administrative	2,693	1,069	6,087	3,057
Total operating expenses	8,910	8,716	26,060	22,554
Loss from operations	(8,910)	(8,716)	(26,060)	(22,554)
Other income (expense):
Interest income	82	344	445	1,111
Interest expense	(258)	(93)	(765)	(93)
Change in fair value of warrant liability	45		(75)
Other income (expense)	(13)		(33)
Total other income (expense)	(144)	251	(428)	1,018
Net loss	(9,054)	(8,465)	(26,488)	(21,536)
Other comprehensive loss:
Unrealized gain (loss) on available-for-sale securities, net	(65)		(27)	115
Comprehensive loss	$ (9,119)	$ (8,465)	$ (26,515)	$ (21,421)
Net loss per share, basic and diluted	$ (1.41)	$ (3.51)	$ (6.89)	$ (9.17)
Weighted average shares of common stock outstanding, basic and diluted	6,436,546	2,409,227	3,845,793	2,349,635