CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
License revenue	$ 3,000	$ 0
Operating expenses:
Research and development	8,911	5,655
General and administrative	4,670	4,783
Total operating expenses	13,581	10,438
Loss from operations	(10,581)	(10,438)
Other expense:
Interest income	296	69
Interest expense	(584)	(399)
Change in fair value of preferred stock warrant liability	0	(288)
Change in fair value of derivative liability	0	183
Other income	41	0
Loss on extinguishment of debt	(162)	0
Total other expense, net	(409)	(435)
Loss before provision for income taxes	(10,990)	(10,873)
Provision for income taxes	148	0
Net loss	(11,138)	(10,873)
Accruing dividends on Series A convertible preferred stock	0	(592)
Net loss attributable to common stockholders	$ (11,138)	$ (11,465)
Net loss per share attributable to common stock holders—basic and diluted (usd per share)	$ (0.56)	$ (6.67)
Weighted average common shares outstanding—basic and diluted (in shares)	20,014,000	1,718,000
Net loss	$ (11,138)	$ (10,873)
Currency translation adjustments	0	23
Total comprehensive loss	$ (11,138)	$ (10,850)