Consolidated Statements of Operations and Comprehensive Loss - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating expenses:
Research and development	$ 34,972,000	$ 20,383,000	$ 37,244,000
General and administrative	12,677,000	11,603,000	9,676,000
Restructuring charges	0	0	605,000
Total operating expenses	47,649,000	31,986,000	47,525,000
Other income (expense):
Interest income (expense), net	(976,000)	(510,000)	270,000
Other expense, net	(38,000)	(349,000)	(84,000)
Other income (expense), net	(1,014,000)	(859,000)	186,000
Net loss	$ (48,663,000)	$ (32,845,000)	$ (47,339,000)
Net loss per share attributable to common stockholders — basic and diluted	$ (0.72)	$ (1.01)	$ (2.13)
Weighted-average common shares outstanding — basic and diluted	67,956,739	32,506,679	22,180,868
Comprehensive loss	$ (48,663,000)	$ (32,845,000)	$ (47,339,000)