Note 10 - Equity Incentive Plans

3 Months Ended

Mar. 31, 2026

Notes to Financial Statements

Share-Based Payment Arrangement [Text Block]

NOTE 10. Equity Incentive Plans

The Company has maintained the 2019 Equity Incentive Plan and the 2024 Inducement Award Plan for the issuance of stock options, stock appreciation rights, restricted stock awards, restricted stock units (“RSUs”), other stock awards and performance awards that may be settled in cash, stock, or other property to employees, directors and consultants. The terms of the 2024 Inducement Award Plan are substantially similar to the terms of the 2019 Equity Incentive Plan, with the exception that incentive stock options may not be issued under the 2024 Inducement Plan and equity awards under the 2024 Inducement Plan (including nonqualified stock options, restricted stock, restricted stock units, and other stock-based awards) may be issued only to an employee who is commencing employment with the Company or any subsidiary or who is being rehired following a bona fide interruption of employment by the Company or any subsidiary, in either case if he or she is granted such award in connection with his or her commencement of employment and such grant is an inducement material to his or her entering into employment with the Company or such subsidiary. The Company also maintains the 2022 Employee Stock Purchase Plan (“ESPP”) for its employees.

A summary of stock option and RSU transactions during the three months ended March 31, 2026 is as follows:

							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

As of March 31, 2026, there were 27,767,619 options outstanding with a weighted average exercise price of $1.62, a weighted average remaining term of 7.40 years, and an aggregate intrinsic value of $667,000. Of these options, 13,614,279 were vested, with a weighted average exercise price of $2.59, a weighted average remaining term of 6.04 years, and an aggregate intrinsic value of $161,000.

No options were exercised during the three months ended March 31, 2026. The Company received $3,000 for the 3,625 options exercised during the three months ended March 31, 2025, which had an intrinsic value of $0. The aggregate intrinsic value represents the total pre-tax value (i.e., the difference between the Company’s stock price and the exercise price) of stock options outstanding as of March 31, 2026 and 2025, respectively, based on the Company’s common stock closing price of $0.61 on March 31, 2026 and $0.85 on March 31, 2025, which would have been received by the option holders had all their in-the-money options been exercised as of that date.

The weighted average grant date fair value of options awarded in the three months ended March 31, 2026 and 2025, was $0.59 and $0.46, respectively. Their fair values were estimated using the following assumptions:

	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		—	%		—	%

The Company measures the fair value of all stock-based awards on the grant date and records the fair value of these awards, net of estimated forfeitures, to compensation expense over the service period. Total stock-based compensation recognized for options, RSUs and ESPP was as follows (in thousands):

	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

As of March 31, 2026, the unrecognized stock-based compensation cost related to outstanding unvested stock options and RSUs expected to vest was $12.1 million, which the Company expects to recognize over an estimated weighted average period of 3.0 years.