CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues:
Total revenues	$ 4,651	$ 7,418	$ 3,573
Operating expenses:
Research and development	53,311	42,534	42,672
General and administrative	20,488	14,456	15,426
Intangible asset impairment	3,500	18,000
Other asset impairment			1,800
Gain on fair value remeasurement of contingent consideration	(1,405)	(4,218)	(1,294)
Total operating expenses	75,894	70,772	58,604
Operating loss	(71,243)	(63,354)	(55,031)
Investment and other income, net	505	2,407	4,153
Net loss before income tax benefit	(70,738)	(60,947)	(50,878)
Income tax benefit	227	1,167
Net loss	$ (70,511)	$ (59,780)	$ (50,878)
Basic net loss per common share	$ (1.64)	$ (2.02)	$ (3.51)
Diluted net loss per common share	$ (1.64)	$ (2.02)	$ (3.51)
Shares used in calculating basic net loss per share	42,870	29,640	14,507
Shares used in calculating diluted net loss per share	42,870	29,640	14,507
Comprehensive loss:
Net loss	$ (70,511)	$ (59,780)	$ (50,878)
Other comprehensive income (loss):
Unrealized (loss) gain on marketable securities	(695)	(30)	36
Comprehensive loss	(71,206)	(59,810)	(50,842)
Product development and licensing agreements
Revenues:
Total revenues	31	2,301	473
Contracts and grants
Revenues:
Total revenues	$ 4,620	$ 5,117	$ 3,100