CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating expenses:
Research and development	$ 8,799	$ 8,058
General and administrative	1,543	1,877
Total operating expenses	10,342	9,935
Total operating loss	(10,342)	(9,935)
Other income (expense):
Interest income	44	1
Change in fair value of derivative	(769)	229
Interest expense	(460)	(227)
Total other income (expense)	(1,185)	3
Net loss	(11,527)	(9,932)
Preferred stock dividends	0	16
Net loss applicable to common stockholders	$ (11,527)	$ (9,916)
Net loss per common share - basic (in dollars per share)	$ (0.19)	$ (0.17)
Net loss per common share - diluted (in dollars per share)	$ (0.19)	$ (0.17)
Weighted average common shares outstanding - basic (in shares)	59,480	59,354
Weighted average common shares outstanding - diluted (in shares)	59,480	59,354