Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating expenses:
Research and development	$ 6,450	$ 4,681	$ 11,349	$ 6,825
General and administrative	1,743	1,421	3,161	2,861
Total operating expenses	8,193	6,102	14,510	9,686
Total operating loss	(8,193)	(6,102)	(14,510)	(9,686)
Other income (expense):
Interest income	1	9	2	59
Interest expense	(85)	(21)	(107)	(43)
Change in fair value of derivative	(172)		(172)	0
Total other income (expense)	(256)	(12)	(277)	16
Net loss	(8,449)	(6,114)	(14,787)	(9,670)
Preferred stock dividends	(65)	(66)	(67)	(60)
Net loss applicable to common stockholders	$ (8,514)	$ (6,180)	$ (14,854)	$ (9,730)
Net loss per common share — basic and diluted	$ (0.15)	$ (0.11)	$ (0.26)	$ (0.17)
Weighted average common shares outstanding — basic and diluted	58,312	57,035	57,725	56,995