Note 10 - Equity Incentive Plans (Tables)

3 Months Ended

Mar. 31, 2024

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, 2024		5,685,806			17,938,726		$	2.90		2,126,373		$	1.37
Authorized under 2024 Inducement Plan		3,000,000
Granted		(6,555,730	)		4,734,937		$	1.16		1,820,793		$	1.16
Exercised					(8,865	)	$	0.78
Released										(429,960	)	$	1.27
Forfeited		981,822			(778,613	)	$	2.40		(203,209	)	$	1.75
Canceled		42,619			(42,619	)	$	3.35
Balance as of March 31, 2024		3,154,517			21,843,566		$	2.54		3,313,997		$	1.24

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

	Three Months Ended March 31,
	2024			2023
Risk-free interest rate		4.4	%		3.5% - 3.6	%
Expected term (in years)		6.00			6.00
Expected volatility		129.1	%		128.0	%
Dividend yield		—	%		—	%

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

	Three Months Ended March 31,
	2024		2023
Research and development	$	1,807	$	1,372
General and administrative		2,309		1,275
Total stock-based compensation	$	4,116	$	2,647

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

	Six-Month Offering Period Ending May 31, 2024			Six-Month Offering Period Ended May 31, 2023
Risk-free interest rate		5.3	%		4.6	%
Expected term (in years)		0.50			0.50
Expected volatility		75.2	%		84.7	%
Dividend yield		—	%		—	%