Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Revenues:
Revenue from license agreement	$ 0	$ 3,000	$ 0	$ 3,000
Revenue from development agreement	72	0	297	62
Revenue from grants	234	0	720	0
Total revenues	306	3,000	1,017	3,062
Cost and expenses:
Research and development	10,218	12,054	19,961	20,146
General and administrative	3,521	6,241	7,473	11,606
Loss on lease termination	0	881	0	881
Total cost and expenses	13,739	19,176	27,434	32,633
Loss from operations	(13,433)	(16,176)	(26,417)	(29,571)
Interest and other income (expenses), net	45	(6)	51	(10)
Net loss	$ (13,388)	$ (16,182)	$ (26,366)	$ (29,581)
Net loss per share:
Net loss per share - basic	$ (0.31)	$ (0.45)	$ (0.61)	$ (0.85)
Net loss per share - diluted	$ (0.31)	$ (0.45)	$ (0.61)	$ (0.85)
Weighted average shares used in calculating:
Weighted Average Number of Shares Outstanding, Basic	43,459	35,707	43,442	34,899
Weighted Average Number of Shares Outstanding, Diluted	43,459	35,707	43,442	34,899
Other comprehensive loss:
Net loss	$ (13,388)	$ (16,182)	$ (26,366)	$ (29,581)
Other comprehensive loss:
Foreign currency translation adjustment (loss) gain	(1)	1	(2)	1
Comprehensive loss	$ (13,389)	$ (16,181)	$ (26,368)	$ (29,580)