CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Operating expenses:
Research and development	$ 7,371	$ 8,074	$ 16,170	$ 16,132
General and administrative	1,632	1,588	3,175	3,465
Total operating expenses	9,003	9,662	19,345	19,597
Total operating loss	(9,003)	(9,662)	(19,345)	(19,597)
Other income (expense):
Interest income	50	3	93	4
Interest expense	(650)	(229)	(1,110)	(456)
Change in fair value of derivative	489	275	(279)	504
Total other income (expense)	(111)	49	(1,296)	52
Net loss	(9,114)	(9,613)	(20,641)	(19,545)
Preferred stock dividends	(63)	(64)	(63)	(48)
Net loss applicable to common stockholders	$ (9,177)	$ (9,677)	$ (20,704)	$ (19,593)
Net loss per common share - basic (in dollars per share)	$ (0.15)	$ (0.16)	$ (0.35)	$ (0.33)
Net loss per common share - diluted (in dollars per share)	$ (0.15)	$ (0.16)	$ (0.35)	$ (0.33)
Weighted average common shares outstanding - basic (in shares)	59,582	59,389	59,531	59,372
Weighted average common shares outstanding - diluted (in shares)	59,582	59,389	59,531	59,372