Condensed Consolidated Statements of Operations and Comprehensive Loss (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Total revenue	$ 1,213	$ 1,100
Operating expenses:
Research and development	4,916	4,827
General and administrative	2,507	2,994
Total operating expenses	7,423	7,821
Operating loss	(6,210)	(6,721)
Other income, net:
Interest income	35	28
Other income, net	8	56
Total other income, net	43	84
Net loss	(6,167)	(6,637)
Comprehensive loss	$ (6,167)	$ (6,637)
Net loss per share, basic and diluted (in USD per share)	$ (0.17)	$ (0.25)
Weighted-average common shares outstanding, basic and diluted (in shares)	37,043,876	26,066,064
License and collaboration revenue
Total revenue	$ 1,024	$ 1,100
Government research contracts and grants revenue
Total revenue	$ 189	$ 0