On March 12, 2018, the board of directors adopted the 2018 Equity Incentive Plan (the “2018 Plan”). The 2018 Plan became effective on April 20, 2018 upon approval by the stockholders of the Company with the outstanding options and shares available for future grant under any prior plans being assumed by the 2018 Plan. During September 2025, the board of directors approved to reset the number of shares of common stock reserved under the 2018 Plan to be 1,818,181 shares. In April 2026, stockholders of the Company ratified and approved this amendment and approved an amendment and restatement of the 2018 Plan in order to extend the period of time during which the Company may grant incentive stock options under the 2018 Plan for ten years. As of June 30, 2026, there were 685,613 shares remaining and available for issuance under the 2018 Plan.

Stock options granted have a ten-year contractual life and, upon termination of service, vested options are generally exercisable between one and three months following the termination date, while unvested options are forfeited immediately.

Transactions related to stock options awarded to employees and directors during the six months ended June 30, 2026 were as follows:


	Shares			Weighted average exercise price		Weighted average remaining contractual life (years)		Aggregate intrinsic value
Options outstanding at December 31, 2025		903,096		$	11.99		9.62	$	893
Granted		169,300			11.00		9.95		—
Exercised		(23,723	)		1.65		—		39
Forfeited		(266	)		—		—		238
Options outstanding at June 30, 2026		1,048,407		$	11.98		9.31	$	8,136
Options exercisable at June 30, 2026		1,048,407		$	11.98		9.31	$	8,136

The aggregate intrinsic value represents the total intrinsic value (the difference between the fair value of the common stock as of June 30, 2026 and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had all option holders exercised their options on June 30, 2026.

Activity related to restricted stock units awarded to employees during the six months ended June 30, 2026 was as follows:


	Shares			Weighted average grant date fair value per share
Unvested at December 31, 2025		4,316		$	0.0011
Granted		—			—
Vested		(2,249	)		0.0011
Forfeited		—			—
Unvested at June 30, 2026		2,067		$	0.0011

Activity related to restricted stock awards awarded to employees during the six months ended June 30, 2026 was as follows:


	Shares			Weighted average grant date fair value per share
Unvested at December 31, 2025		15,683		$	0.0011
Granted		—			—
Vested		(2,616	)		0.0011
Repurchased		—			—
Unvested at June 30, 2026		13,067		$	0.0011

Stock-based compensation relates to employees, non-employee directors and non-employee consultants, time-based stock options, performance-based stock options, restricted stock awards, and restricted stock units granted. Total stock-based compensation expense related to all of the Company’s stock-based awards was recognized as follows (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2026		2025		2026		2025
Research and development	$	34	$	13	$	50	$	28
General and administrative		61		3		91		8
Total stock-based compensation expense	$	95	$	16	$	141	$	36