CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Revenue	$ 1,222	$ 935
Operating expenses:
Research and development	13,771	10,683
General and administrative	4,012	3,289
Total operating expenses	17,783	13,972
Loss from operations	(16,561)	(13,037)
Other income, net	47	135
Net loss before taxes	(16,514)	(12,902)
Provision for income taxes		237
Net loss	(16,514)	(13,139)
Other comprehensive income (loss):
Foreign currency translation adjustment	38	204
Unrealized gain (loss) on marketable securities	(50)	(217)
Total comprehensive loss	$ (16,526)	$ (13,152)
Net loss per share, basic and diluted	$ (0.66)	$ (0.56)
Weighted average number of shares used in computing net loss per share, basic and diluted	24,844,946	23,266,063