Note 10 - Equity Incentive Plans (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2026

Dec. 31, 2025

Notes Tables

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

										*Weighted*								*Weighted*
		*Shares*				*Number of*				*Option Average*				*Unvested*				*RSU Average*
		*Available*				*Options*				*Exercise*				*RSU Shares*				*Grant Date*
		*For Grant*				*Outstanding*				*Price*				*Outstanding*				*Fair Value*

Balance as of January 1, 2026			10,875,110				25,407,299			$	1.96				5,733,306			$	0.70
Granted			(7,990,020	)			5,280,640			$	0.68				2,709,380			$	0.68
Exercised			—				—			$	—				—			$	—
Released			—				—			$	—				(1,426,449	)		$	0.77
Forfeited			743,521				(418,889	)		$	0.88				(324,632	)		$	0.93
Canceled			2,491,495				(2,501,431	)		$	3.19				—			$	—

Balance as of March 31, 2026			6,120,106				27,767,619			$	1.62				6,691,605			$	0.67

										*Weighted*								*Weighted*
		*Shares*				*Number of*				*Option Average*				*Number of*				*RSU Average*
		*Available*				*Options*				*Exercise*				*RSUs*				*Grant Date*
		*For Grant*				*Outstanding*				*Price*				*Outstanding*				*Fair Value*

Balance at January 1, 2024			5,685,806				17,938,726			$	2.90				2,126,373			$	1.37

Authorized under 2024 Inducement Plan			3,000,000				—			$	—				—			$	—
Authorized under 2019 Plan Amendment			15,000,000				—			$	—				—			$	—
Granted			(7,258,980	)			5,309,437			$	1.12				1,949,543			$	1.13
Exercised			—				(38,030	)		$	0.78				—			$	—
Released			—				—			$	—				(599,260	)		$	1.48
Forfeited			1,944,001				(1,483,826	)		$	2.29				(460,175	)		$	1.41
Canceled			1,279,297				(1,321,068	)		$	2.87				—			$	—
Balance at December 31, 2024			19,650,124				20,405,239			$	2.49				3,016,481			$	1.19

Granted			(12,969,746	)			8,281,792			$	0.53				4,687,954			$	0.51
Exercised			—				(3,625	)		$	0.78				—			$	—
Released			—				—			$	—				(1,041,423	)		$	1.13
Forfeited			2,781,683				(1,851,977	)		$	0.94				(929,706	)		$	0.83
Canceled			1,413,049				(1,424,130	)		$	2.47				—			$	—
Balance at December 31, 2025			10,875,110				25,407,299			$	1.96				5,733,306			$	0.70

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

		*Three Months Ended March 31,*
		*2026*				*2025*

Risk-free interest rate			3.9	%			4.1% - 4.4%
Expected term (in years)			6.0				6.0
Expected volatility			118.4	%			126.5	%
Dividend yield			—	%			—	%

		*Year Ended December 31,*
		*2025*				*2024*

Risk-free interest rate			3.8% - 4.4%				3.7% - 4.4%
Expected term (in years)			5.50 - 6.00				5.50 - 6.00
Expected volatility			125.6% - 128.6%				128.9% - 130.8%
Dividend yield			—	%			—%

Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

		*Three Months Ended March 31,*
		*2026*				*2025*

Research and development		$	812			$	1,702
General and administrative			670				757
Total stock-based compensation		$	1,482			$	2,459

		*Year Ended December 31,*
		*2025*				*2024*

Research and development		$	5,554			$	7,246
General and administrative			2,760				4,255
Total stock-based compensation		$	8,314			$	11,501