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
Income Statement [Abstract]
License revenue	$ 0	$ 0	$ 3,000	$ 0
Operating expenses:
Research and development	11,381	8,589	29,634	23,098
General and administrative	5,599	4,383	15,585	13,726
Loss on transfer of non-financial assets	0	4,004	0	4,004
Total operating expenses	16,980	16,976	45,219	40,828
Loss from operations	(16,980)	(16,976)	(42,219)	(40,828)
Other income (expense):
Interest income	0	464	272	927
Interest expense	(697)	(688)	(1,968)	(1,599)
Change in fair value of preferred stock warrant liability	0	0	0	(288)
Change in fair value of derivative liability	0	0	0	183
Other income	228	52	494	201
Loss on extinguishment of debt	0	(566)	(162)	(566)
Total other expense, net	(469)	(738)	(1,364)	(1,142)
Loss before provision for income taxes	(17,449)	(17,714)	(43,583)	(41,970)
Provision for income taxes	0	0	148	0
Net loss	(17,449)	(17,714)	(43,731)	(41,970)
Accruing dividends on Series A convertible preferred stock	0	0	0	(592)
Net loss attributable to common stockholders	$ (17,449)	$ (17,714)	$ (43,731)	$ (42,562)
Net loss per share attributable to common stock holders—basic and diluted (usd per share)	$ (0.87)	$ (1.22)	$ (2.18)	$ (4.31)
Weighted average common shares outstanding—basic and diluted (in shares)	20,085,000	14,562,000	20,035,000	9,866,000
Net loss	$ (17,449)	$ (17,714)	$ (43,731)	$ (41,970)
Currency translation adjustments	0	(77)	0	(119)
Total comprehensive loss	$ (17,449)	$ (17,791)	$ (43,731)	$ (42,089)