Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues, net:
Total revenues, net	$ 10,649	$ 10,835	$ 10,004
Costs and expenses:
Cost of royalties	533	534	503
Research and development	34,884	23,068	22,302
General and administrative	17,297	12,131	11,555
Total costs and expenses	52,714	35,733	34,360
Loss from operations	(42,065)	(24,898)	(24,356)
Other expense:
Loss on debt extinguishment	0	0	(3,495)
Interest income	211	63	614
Imputed interest expense related to the sale of future royalties	(4,472)	(5,095)	(4,055)
Interest expense, debt	0	0	(791)
Other income (expense), net	890	22	(58)
Total other expense	(3,371)	(5,010)	(7,785)
Net loss	$ (45,436)	$ (29,908)	$ (32,141)
Net loss per common share, basic (in dollars per share)	$ (0.50)	$ (0.61)	$ (0.97)
Net loss per common share, diluted (in dollars per share)	$ (0.50)	$ (0.61)	$ (0.97)
Weighted average common shares, basic (in shares)	91,569,154	48,670,381	33,180,516
Weighted average common shares, diluted (in shares)	91,569,154	48,670,381	33,180,516
Unrealized net loss on marketable securities	$ (106)	$ (3)	$ 0
Total comprehensive loss	(45,542)	(29,911)	(32,141)
Royalties
Revenues, net:
Total revenues, net	10,749	10,724	10,418
Other revenue
Revenues, net:
Total revenues, net	1	214	0
Contra revenue, net
Revenues, net:
Total revenues, net	$ (101)	$ (103)	$ (414)