Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating expenses:
Research and development	$ 11,591	$ 10,137
General and administrative	4,544	3,365
Total operating expenses	16,135	13,502
Loss from operations	(16,135)	(13,502)
Other income (expense), net:
Changes in fair value of warrant liabilities	(16,240)
Other income, net	541	325
Total other income (expense), net	(15,699)
Loss before provision for (benefit from) income taxes, net	(31,834)	(13,177)
Provision for (benefit from) income taxes, net	78	(145)
Net loss and comprehensive loss	$ (31,912)	$ (13,032)
Net loss per common share, basic and diluted	$ (3.14)	$ (7.00)
Weighted-average shares used in computing net loss per common share, basic and diluted	10,156,628	1,862,132