Condensed Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating expenses:
Research and development	$ 9,987	$ 6,460
General and administrative	3,388	3,017
Total operating expenses	13,375	9,477
Loss from operations	(13,375)	(9,477)
Other income (expense):
Change in fair value of warrants	781	(5,787)
Interest expense, net	(259)	(302)
Other income (expense)	0	(1)
Total other income (expense)	522	(6,090)
Net loss	(12,853)	(15,567)
Comprehensive loss	$ (12,853)	$ (15,567)
Net loss per share - basic and diluted	$ (0.46)	$ (1.22)
Weighted-average number of common shares used in computing net loss per share (in shares)		12,713