Unaudited Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ 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	$ 12,720	$ 10,009	$ 26,470	$ 17,694
General and administrative	6,289	5,198	11,287	10,679
Total operating expenses	19,009	15,207	37,757	28,373
Loss from operations	(19,009)	(15,207)	(37,757)	(28,373)
Interest income	46	617	404	1,287
Other income (expense)	(12)	151	(7)	151
Loss before income tax provision (benefit)	(18,975)	(14,439)	(37,360)	(26,935)
Income tax provision (benefit)	(386)	4	(3,695)	9
Net loss	(18,589)	(14,443)	(33,665)	(26,944)
Comprehensive loss	$ (18,589)	$ (14,443)	$ (33,665)	$ (26,944)
Net loss per common share:
Basic and diluted (in dollars per share)	$ (0.32)	$ (0.35)	$ (0.61)	$ (0.65)
Weighted average common shares outstanding:
Basic and diluted (in shares)	57,421	41,477	55,424	41,452