On May 7, 2018, the Company established and adopted the 2018 Equity Incentive Plan (the "2018 Plan") providing for the granting of stock awards for employees, directors and consultants to purchase shares of the Company’s common stock. Upon the effectiveness of the 2020 Plan (as defined below), the 2018 Plan was terminated and no further issuances were made under the 2018 Plan, although it continues to govern the terms of any equity grants that remain outstanding under the 2018 Plan.

The 2020 Equity Incentive Plan (the "2020 Plan") was approved by the Company's Board of Directors and the Company’s stockholders and became effective on July 29, 2021. Upon the effectiveness of the 2023 Plan (as defined below), the 2020 Plan was terminated and no further issuances were made under the 2020 Plan, although it continues to govern the terms of any equity grants that remain outstanding under the 2020 Plan.

The Amended and Restated 2023 Equity Incentive Plan (the "2023 Plan") was approved by the Company's Board of Directors and the Company’s stockholders and became effective on June 15, 2023. Upon the effectiveness of the 2026 Plan (as defined below), the 2023 Plan was terminated and no further issuances were made under the 2023 Plan, although it continues to govern the terms of any equity grants that remain outstanding under the 2023 Plan.

The Amended and Restated 2026 Equity Incentive Plan (the "2026 Plan") was approved by the Company's Board of Directors and the Company’s stockholders and became effective on May 7, 2026. The Board of Directors, or a committee thereof, is authorized to administer the 2026 Plan. The 2026 Plan provides for the grant of Incentive Stock Options ("ISO") within the meaning of Section 422 of the Internal Revenue Code of 1986 as amended, to employees, and for the grant of non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance awards and other forms of awards to the Company’s employees, directors and consultants and any Company affiliates’ employees and consultants. The number of shares initially reserved for issuance under the 2026 Plan was 4,054,937, which automatically increases on January 1 of each year for a period of 10 years commencing on January 1, 2027 and ending on (and including) January 1, 2037, in an amount equal to 5% of the total number of shares of common stock, plus the total number of shares of common stock issuable upon settlement of pre-funded warrants (if any), in each case, outstanding on December 31 of the preceding year, or a lesser number of shares determined by the Board of Directors no later than the last day of the immediately preceding year. The maximum number of shares of common stock that may be issued upon the exercise of ISOs under the 2026 Plan is 20,000,000 shares. As of June 30, 2026, 2,474,975 shares were available for grant pursuant to the 2026 Plan.

The 2020 Employee Stock Purchase Plan (the "2020 ESPP") was approved by the Board of Directors and the Company’s stockholders and became effective on July 29, 2021. A total of 6,666 shares of common stock were initially reserved for issuance under this plan, which automatically increases on January 1 of each year by the lesser of (i) 1% of the outstanding number of shares of common stock on the immediately preceding December 31; and (ii) 13,333, or such lesser number of shares as determined by the Board of Directors. As of June 30, 2026, no shares of common stock had been issued under the ESPP and 26,260 shares remained available for

future issuance under the ESPP. The Board of Directors or designated committee has not set an offering period and the Board of Directors elected not to increase the number of shares of common stock reserved for future issuance under the ESPP as of January 1, 2026.

The following is a summary of the stock option award activity during the six months ended June 30, 2026:


	Number of Stock Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2025		502,027		$	50.42		8.05	$	41
Granted		1,083,658			1.75
Exercised		—			—
Forfeited		(5,723	)		8.01
Outstanding at June 30, 2026		1,579,962		$	17.19		8.85	$	—
Exercisable at June 30, 2026		415,044		$	56.48		6.72	$	—
Options expected to vest as of June 30, 2026		1,164,918		$	3.19		9.60	$	—

The weighted-average grant date fair value of options granted during the six months ended June 30, 2026 and 2025 was $1.41 and $6.70, respectively. The aggregate intrinsic value is calculated as the difference between the exercise price and the market price of the Company’s common stock at June 30, 2026 and December 31, 2025.

For the six months ended June 30, 2026 and 2025, the Company utilized the Black-Scholes option-pricing model for estimating the fair value of the stock options. The following table presents the assumptions and the Company’s methodology for developing each of the assumptions used:


	June 30, 2026	June 30, 2025
Volatility	101.73% - 102.98%	96.66% - 99.24%
Expected life (years)	5.27 - 6.08	5.27 - 6.08
Risk-free interest rate	3.83% - 4.07%	4.00% - 4.24%
Dividend rate	—	—

Stock-based compensation expense was recorded in the following line items in the condensed statements of operations for the three and six months ended June 30, 2026 and 2025 (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2026		2025		2026		2025
Research and development	$	131	$	298	$	298	$	584
General and administrative		221		657		455		1,202
Total stock-based compensation expense	$	352	$	955	$	753	$	1,786

No related tax benefits from stock-based compensation expense were recognized for the three and six months ended June 30, 2026 and 2025. As of June 30, 2026, there was $2.7 million in unrecognized stock-based compensation expense, which is expected to be recognized over a weighted-average period of 2.27 years.