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
Operating expenses:
Research and development	$ 7,877	$ 3,489	$ 14,283	$ 7,623
General and administrative	1,671	1,064	3,171	2,094
Total operating expenses	9,548	4,553	17,454	9,717
Loss from operations	(9,548)	(4,553)	(17,454)	(9,717)
Other income (expense):
Interest income	71	394	242	604
Other income (expense), net	4	(14)	1	(31)
Other income (expense), net	75	380	243	573
Net loss	(9,473)	(4,173)	(17,211)	(9,144)
Other comprehensive (loss) income:
Unrealized (losses) gains on available-for-sale securities	(15)	10	8	12
Total other comprehensive (loss) income	(15)	10	8	12
Comprehensive loss	(9,488)	(4,163)	(17,203)	(9,132)
Net loss attributable to common stockholders—basic and diluted	$ (9,473)	$ (4,173)	$ (17,211)	$ (9,144)
Net loss per share attributable to common stockholders—basic and diluted	$ (7.57)	$ (3.57)	$ (14.01)	$ (7.83)
Weighted-average common shares outstanding—basic and diluted	1,251,244	1,170,480	1,228,296	1,167,346