Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Revenue
Total revenue	$ 5,685	$ 4,753
Operating expenses
Research and development	17,620	12,836
General and administrative	13,065	13,691
Loss on impairment of long-lived assets	5,784
Total operating expenses	36,469	26,527
Loss from operations	(30,784)	(21,774)
Interest income	255	1,022
Other income (expense), net	(14)	2,534
Net loss	$ (30,543)	$ (18,218)
Net loss per share- basic and diluted	$ (1.93)	$ (1.57)
Weighted-average common shares used to compute net loss per share- basic and diluted	15,790	11,589
Grant Revenue [Member]
Revenue
Total revenue		$ 4,753
Collaboration Revenue [Member]
Revenue
Total revenue	$ 5,685