CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
License revenue	$ 0	$ 0	$ 0	$ 3,000
Operating expenses:
Research and development	13,188	11,381	38,485	29,634
General and administrative	5,931	5,599	17,567	15,585
Total operating expenses	19,119	16,980	56,052	45,219
Loss from operations	(19,119)	(16,980)	(56,052)	(42,219)
Other income (expense):
Interest income	2	0	7	272
Interest expense	(920)	(697)	(2,717)	(1,968)
Change in fair value of derivative liability	(62)	0	(36)	0
Other income, net	(74)	228	323	494
Loss on extinguishment of debt	0	0	0	(162)
Total other expense, net	(1,054)	(469)	(2,423)	(1,364)
Loss before provision for income taxes	(20,173)	(17,449)	(58,475)	(43,583)
Provision for income taxes	2	0	14	148
Net loss and comprehensive loss	(20,175)	(17,449)	(58,489)	(43,731)
Deemed dividend on Class B Warrant price reset	0	0	(8,239)	0
Net loss attributable to common stockholders	$ (20,175)	$ (17,449)	$ (66,728)	$ (43,731)
Net loss per share attributable to common stockholders—basic and diluted	$ (0.76)	$ (0.87)	$ (2.71)	$ (2.18)
Weighted average common shares outstanding—basic and diluted (in shares)	26,609,000	20,085,000	24,667,000	20,035,000