Note 6 - Stock Based Compensation (Tables)

12 Months Ended

Dec. 31, 2024

Notes Tables

Share-based Payment Arrangement, Expensed, Amount [Table Text Block]

	Year Ended December 31,
	2024		2023
General and administrative	$	1,310	$	1,439
Research and development		416		545
Total stock-based compensation	$	1,726	$	1,984

Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Year Ended December 31,
	2024		2023
Risk-free interest rate		4.0% to 4.5%		3.9% to 4.6%
Volatility		89.1% to 98.9%		96.0% to 101.2%
Expected life (years)		5.1 to 6.3		5.5 to 6.3
Expected dividend yield		—%		—%

Share-Based Payment Arrangement, Option, Activity [Table Text Block]

	Number of Shares			Weighted Average Grant Date Fair Value		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Outstanding, December 31, 2023		249,492		$	43.35	$	56.70		7.9	$	378,606
Granted		542,667		$	2.01	$	2.52
Forfeited		(6,664	)	$	13.90	$	16.50
Expired		(967	)	$	15.44	$	18.30
Outstanding, December 31, 2024		784,528		$	15.03	$	19.60		8.9	$	—
Exercisable, December 31, 2024		156,413		$	60.35	$	80.04		6.2	$	—

Schedule of Nonvested Restricted Stock Units Activity [Table Text Block]

	Number of Shares			Weighted Average Grant Date Fair Value		Weighted Average Remaining Contractual Term (years)
Unvested Shares, December 31, 2023		93,895		$	15.49		7.3
Granted		340,834		$	2.48
Vested		(27,348	)	$	19.65
Unvested Shares, December 31, 2024		407,381		$	4.32		2.9