Note 6 - Stockholders' Equity and Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2025

Notes Tables

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

	Three Months Ended June 30,				Six Months Ended June 30,
	2025		2024		2025		2024
Research and development	$	2,335	$	1,001		5,097		1,950
General and administrative		2,854		1,051		5,773		1,861
Total stock-based compensation expense	$	5,189	$	2,052	$	10,870	$	3,811

	Three Months Ended June 30,				Six Months Ended June 30,
	2025		2024		2025		2024
Time-based options	$	3,579	$	1,315	$	7,686	$	2,478
Performance-based options		—		14		—		22
Market-based options		1,535		683		3,004		1,190
ESPP		75		40		180		121
Total stock-based compensation expense	$	5,189	$	2,052	$	10,870	$	3,811

The 2015 Plan, 2017 Plan and Inducement Plan [Member]

Notes Tables

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

	Stock Options Outstanding
	Number of shares			Weighted average exercise price		Weighted average remaining life (in years)
Balances — December 31, 2024		10,979,332		$	9.59		7.11
Options granted		2,632,900			18.92
Options exercised		(54,750	)		7.16
Options canceled		(46,000	)		15.10
Options expired		—			—
Balances — June 30, 2025		13,511,482		$	11.40		7.23
Exercisable — June 30, 2025		4,988,292		$	12.81		4.92

The 2017 Employee Stock Purchase Plan [Member]

Notes Tables

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

	Three Months Ended June 30,				Six Months Ended June 30,
	2025		2024		2025		2024
Expected term in years		0.5 - 1.0		0.5 - 1.0		0.5 - 1.0		0.5 - 1.0
Expected volatility		98%		98%		98%		98%
Risk-free interest rate		4.1% - 4.3%		4.9% - 5.3%		4.1% - 4.3%		4.9% - 5.3%
Dividend yield		—		—		—		—

Performance-based and Market-based Options [Member]

Notes Tables

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

	Stock Options Outstanding
	Number of shares		Weighted average exercise price		Weighted average remaining life (in years)
Balances — December 31, 2024		—	$	—		—
Options granted		1,200,000		18.74
Options exercised		—		—
Options canceled		—		—
Options expired		—		—
Balances — June 30, 2025		1,200,000	$	18.74		9.54
Exercisable — June 30, 2025		—	$	—		—

Market-based Options [Member]

Notes Tables

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

	Stock Options Outstanding
	Number of shares		Weighted average exercise price		Weighted average remaining life (in years)
Balances — December 31, 2024		2,461,389	$	6.95		8.43
Options granted		232,500		19.44
Options exercised		—		—
Options canceled		—		—
Options expired		—		—
Balances — June 30, 2025		2,693,889	$	8.03		8.08
Exercisable — June 30, 2025		—	$	—		—

Share-Based Payment Arrangement, Option [Member]

Notes Tables

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

	Three Months Ended June 30,				Six Months Ended June 30,
	2025		2024		2025		2024
Expected term in years		6.3		5.3 - 6.3		5.0 - 6.9		5.3 - 6.3
Expected volatility		94%		91% - 95%		93% - 100%		91% - 95%
Risk-free interest rate		4.2% - 4.3%		4.1%		4.1% - 4.6%		4.0% - 4.5%
Dividend yield		—		—		—		—

	Three Months Ended June 30,				Six Months Ended June 30,
	2025		2024		2025		2024
Expected term in years		—		3.7 - 5.8		5.5 - 7.0		3.7 - 5.8
Expected volatility		—		90%		90%		90%
Risk-free interest rate		—		4.4%		4.5% - 4.6%		4.2% - 4.4%
Dividend yield		—		—		—		—

	Three Months Ended June 30,				Six Months Ended June 30,
	2025		2024		2025		2024
Expected term in years		—		—		6.1 - 8.9		—
Expected volatility		—		—		90%		—
Risk-free interest rate		—		—		4.4% - 4.6%		—
Dividend yield		—		—		—		—

Performance Options [Member]

Notes Tables

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

	Stock Options Outstanding
	Number of shares		Weighted average exercise price		Weighted average remaining life (in years)
Balances — December 31, 2024		442,678	$	7.71		6.79
Options granted		—		—
Options exercised		—		—
Options canceled		—		—
Options expired		—		—
Balances — June 30, 2025		442,678	$	7.71		6.29
Exercisable — June 30, 2025		437,678	$	7.70		6.27

Time-based Options [Member]

Notes Tables

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

	Stock Options Outstanding
	Number of shares			Weighted average exercise price		Weighted average remaining life (in years)
Balances — December 31, 2024		8,075,265		$	10.49		6.72
Options granted		1,200,400			19.00
Options exercised		(54,750	)		7.16
Options canceled		(46,000	)		15.10
Options expired		—			—
Balances — June 30, 2025		9,174,915		$	11.60		6.72
Exercisable — June 30, 2025		4,550,614		$	13.30		4.79