CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenues:
Grant revenue	$ 924	$ 2,356	$ 3,843	$ 12,698
Collaboration revenue	$ 1,082	$ 708	$ 2,225	$ 2,814
Type of Revenue [Extensible List]	us-gaap:LicenseMember	us-gaap:LicenseMember	us-gaap:LicenseMember	us-gaap:LicenseMember
Total revenues	$ 2,006	$ 3,064	$ 6,068	$ 15,512
Operating expenses:
Research and development	7,360	14,436	32,504	47,301
General and administrative	6,632	11,152	29,988	28,680
Restructuring	(152)	0	11,697	0
Total operating expenses	13,840	25,588	74,189	75,981
Loss from operations	(11,834)	(22,524)	(68,121)	(60,469)
Other income (expense):
Interest income	208	90	391	270
Other income (expense), net	(23)	(87)	(46)	(317)
Interest expense related to the sale of future royalties	(0)	0	(2,605)	0
Loss on extinguishment of liability related to the sale of future royalties	0	0	(3,581)	0
Change in fair value of derivative liability	(26)	0	776	0
Total other income (expense), net	159	3	(5,065)	(47)
Net loss	$ (11,675)	$ (22,521)	$ (73,186)	$ (60,516)
Net loss per share, basic and diluted	$ (0.33)	$ (0.70)	$ (2.16)	$ (1.99)
Net loss per share, basic and diluted	$ (0.33)	$ (0.70)	$ (2.16)	$ (1.99)
Weighted average common shares outstanding, basic and diluted	35,882,076	32,132,500	33,834,198	30,417,305
Weighted average common shares outstanding, basic and diluted:	35,882,076	32,132,500	33,834,198	30,417,305
Comprehensive loss:
Net loss	$ (11,675)	$ (22,521)	$ (73,186)	$ (60,516)
Other comprehensive gain (loss):
Unrealized gain (loss) on marketable securities	0	0	2	5
Net unrealized gains (losses) on securities	0	0	2	5
Total comprehensive loss	$ (11,675)	$ 22,521	$ (73,184)	$ (60,511)