CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating expenses:
Research and development	$ 23,818	$ 17,976
General and administrative	6,361	5,468
Total operating expenses	30,179	23,444
Total operating loss	(30,179)	(23,444)
Other income (expense):
Interest income	3	66
Interest expense	(489)	(87)
Change in fair value of derivative	138	0
Total other income (expense)	(348)	(21)
Net loss	(30,527)	(23,465)
Preferred stock dividends	(171)	(137)
Net loss applicable to common stockholders	$ (30,698)	$ (23,602)
Net loss per share - basic (in dollars per share)	$ (0.52)	$ (0.41)
Net loss per share - diluted (in dollars per share)	$ (0.52)	$ (0.41)
Weighted average common and potential common shares outstanding - basic (in shares)	58,527	57,029
Weighted average common and potential common shares outstanding - diluted (in shares)	58,527	57,029