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	$ 6,466	$ 5,981	$ 14,006	$ 12,185
General and administrative	4,138	4,179	8,733	8,632
Loss from operations	10,604	10,160	22,739	20,817
Other expenses (income):
Interest income, net	(5)	(313)	(167)	(628)
Other loss	73	24	98	48
Net loss	$ (10,672)	$ (9,871)	$ (22,670)	$ (20,237)
Net loss per share of common stock, basic and diluted (in USD per share)	$ (0.56)	$ (0.74)	$ (1.21)	$ (1.51)
Weighted-average shares of common stock outstanding, basic and diluted (in shares)	18,999,223	13,379,842	18,723,865	13,368,981
Other comprehensive income (loss):
Foreign currency translation adjustment	$ (5)	$ 1	$ (47)	$ (8)
Comprehensive loss	$ (10,677)	$ (9,870)	$ (22,717)	$ (20,245)