CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Statement [Abstract]
License revenue	$ 214	$ 0	$ 645	$ 12,000
Revenue from Contract with Customer, Product and Service [Extensible List]	License revenue	License revenue	License revenue	License revenue
Operating expenses:
Research and development	$ 4,162	$ 3,447	$ 6,885	$ 8,809
General and administrative	5,173	7,284	10,291	13,861
Total operating expenses	9,335	10,731	17,176	22,670
Loss from operations	(9,121)	(10,731)	(16,531)	(10,670)
Other income (expense):
Interest income	20	33	42	65
Interest expense	(1,066)	(1,077)	(2,094)	(2,106)
Other expense	(1)	0	(55)	0
Total other expense	(1,047)	(1,044)	(2,107)	(2,041)
Net loss	$ (10,168)	$ (11,775)	$ (18,638)	$ (12,711)
Net loss per share, basic	$ (0.37)	$ (0.43)	$ (0.68)	$ (0.46)
Net loss per share, diluted	$ (0.37)	$ (0.43)	$ (0.68)	$ (0.46)
Weighted average common shares outstanding, basic	27,519,053	27,513,665	27,519,053	27,697,985
Weighted average common shares outstanding, diluted	27,519,053	27,513,665	27,519,053	27,697,985
Net loss	$ (10,168)	$ (11,775)	$ (18,638)	$ (12,711)
Other comprehensive gain:
Unrealized loss on marketable securities	(2)	(4)	(35)	(2)
Comprehensive loss	$ (10,170)	$ (11,779)	$ (18,673)	$ (12,713)