Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Statement [Abstract]
Revenue-supply agreement	$ 0	$ 0	$ 8,000	$ 0
Operating expenses
Research and development	4,808,000	5,089,000	12,024,000	9,575,000
General and administrative	2,259,000	1,448,000	3,696,000	2,901,000
Total operating expenses	7,067,000	6,537,000	15,720,000	12,476,000
Loss from operations	(7,067,000)	(6,537,000)	(15,712,000)	(12,476,000)
Other income (expense):
Interest income	3,000	13,000	8,000	27,000
Change in fair value of warrant derivative liability	(288,000)	2,523,000	286,000	886,000
Total other income (expense)	(285,000)	2,536,000	294,000	913,000
Net loss	(7,352,000)	(4,001,000)	(15,418,000)	(11,563,000)
Net loss attributable to common stockholders	(7,352,000)	(4,001,000)	(15,418,000)	(11,563,000)
Net loss attributable to common stockholders	$ (7,352,000)	$ (4,001,000)	$ (15,418,000)	$ (11,563,000)
Net loss per common share attributable to common stockholders, basic (in dollars per share)	$ (0.24)	$ (0.13)	$ (0.50)	$ (0.38)
Net loss per common share attributable to common stockholders, diluted (in dollars per share)	$ (0.24)	$ (0.13)	$ (0.50)	$ (0.38)
Weighted-average shares outstanding, basic (in shares)	30,835,261	30,829,184	30,834,911	30,824,407
Weighted-average shares outstanding, diluted (in shares)	30,835,261	30,829,184	30,834,911	30,824,407
Net loss	$ (7,352,000)	$ (4,001,000)	$ (15,418,000)	$ (11,563,000)
Other comprehensive loss:
Foreign currency translation adjustment	0	(2,000)	0	(5,000)
Comprehensive loss	$ (7,352,000)	$ (4,003,000)	$ (15,418,000)	$ (11,568,000)