In 2017, the Company adopted the 2017 Equity Incentive Plan (the “2017 Plan”).

On November 10, 2021, the 2017 Plan terminated and was replaced by the 2021 Plan (defined below), and future issuances of incentive instruments will be governed by the 2021 Plan. To the extent that outstanding awards under the 2017 Plan are forfeited or lapse unexercised, the shares of common stock subject to such awards will no longer be available for future issuance.

2021 Equity Incentive Plan

In 2021, the Company adopted the 2021 Equity Incentive Plan (the “2021 Plan”). The plan allows for the issuance of incentive stock options, nonstatutory stock options, restricted stock awards, restricted stock units, stock bonus awards and performance-based awards. Awards granted under the 2021 Plan are determined by the Compensation Committee of the Company’s board of directors, who is responsible for administering the 2021 Plan. The term for stock options shall be no more than ten years from the date of grant. In the case of an Incentive Stock Option granted to an optionee who, at the time the option is granted, owns stock representing more than 10% of the voting power of all classes of stock of the Company or any Parent or Subsidiary, the term of the option shall be five years from the date of grant or such shorter term as may be provided in the option Agreement. To the extent outstanding awards under the 2021 Plan are forfeited or lapse unexercised, the shares of common stock subject to such awards will be available for future issuance under the 2021 Plan. The 2021 Plan provides that additional shares will automatically be added to the shares authorized for issuance under the 2021 Plan on January 1 of each year. The number of shares added each year will be equal to the lesser of: (i) 5.0% of the outstanding shares of the Company’s common stock on December 31st of the preceding calendar year or (ii) such number of shares determined by the board of directors, in its discretion. On January 1, 2024, 4,312 shares were automatically added to the number of shares authorized for issuance under 2021 Plan (an increase equal to 5% of the number of the outstanding shares of Company common stock as of December 31, 2023).

Amended and Restated 2021 Equity Incentive Plan

On August 9, 2024, the Company adopted its Amended and Restated 2021 Equity Incentive Plan (the "A&R2021 Plan”), which amended and restated the 2021 Plan in full to, amongst other things, increase the number of shares of common stock authorized for issuance thereunder from5,434 shares to 58,823 shares. The Company’s Board of Directors unanimously approved the adoption of the A&R2021 Plan, subject to stockholder approval, on June 15, 2024, and the Company’s stockholders approved the A&R2021 Plan at the Company’s 2024 Annual Meeting of Stockholders held on August 9, 2024. On January 1, 2025, 27,846 shares were automatically added to the number of shares authorized for issuance under A&R2021 Plan (an increase equal to 5% of the number of the outstanding shares of Company common stock as of December 31, 2024). On January 1, 2026, 126,289 shares were automatically added to the number of shares authorized for issuance under 2021 Plan (an increase equal to 5% of the number of the outstanding shares of Company common stock as of December 31, 2025).

On June 30, 2025, following stockholder approval, the Company further amended the A&R 2021 Plan to increase the number of shares of common stock authorized for issuance thereunder from 86,669 to 511,669 shares.

As of December 31, 2025, there were 101,105 shares of common stock available for issuance under the 2021 Plan.

Stock Options

In the case of an Incentive Stock Option, (i) granted to an employee who, at the time of grant of such option, owns stock representing more than 10% of the voting power of all classes of stock of the Company or any Parent or Subsidiary, the exercise price shall be no less than 110% of the Fair Market Value per Share on the date of grant; (ii) granted to any other employee, the per share exercise price shall be no less than 100% of the Fair Market Value per Share on the date of grant. In the case of a Non-statutory Stock Option, the per share exercise price shall be no less than 100% of the Fair Market Value per Share on the date of grant. Notwithstanding the foregoing, options may be granted with a per share exercise price other than as required above pursuant to a merger or other corporate transaction.

The options may include provisions permitting exercise of the option prior to full vesting. Any unvested shares upon termination shall be subject to repurchase by the Company at the original exercise price of the option. Stock options granted under the Company’s equity incentive plans generally vest over four years from the date of grant.

The following table summarizes the stock option award activity for the years ended December 31, 2025 and 2024:

The weighted-average grant date fair value per share of stock options granted in 2025 and 2024 was $2.82 and $8.33, respectively. The aggregate intrinsic value of options outstanding and options vested and exercisable as of December 31, 2025 is calculated based on the difference between the exercise price and the current fair value of our common stock. There was no intrinsic value as of December 31, 2025 as there were no awards with an exercise price lower than our closing stock price of $1.45 on December 31, 2025.

Stock-Based Compensation for Stock Options

Options generally vest over four years whereby 25% vest upon the first anniversary of the issuance date and either 1/36th per month thereafter or 1/12th per quarter thereafter. Stock-based compensation expense related to stock options during the years ended December 31, 2025 and 2024 was $332 thousand and $229 thousand, respectively. As of December 31, 2025, there was $974 thousand of remaining expense, which is expected to be amortized over 3.07 years.

The weighted-average exercise price as of December 31, 2025, for stock options outstanding and stock options exercisable was $8.00 and $114.62, respectively. The weighted average remaining contractual life as of December 31, 2025, for stock options outstanding and stock options exercisable was 9.60 and 8.46 years, respectively.

Prior to the IPO, the grant date fair market value of the shares of common stock underlying stock options had historically been determined by the Company’s Board of Directors. Because there had been no public market for the Company’s common stock, the Board of Directors exercised reasonable judgment and considered a number of objective and subjective factors to determine the best estimate of the fair market value, which included valuations performed by an independent third-party, important developments in the Company's operations, sales of the Company’s convertible preferred stock, actual operating results, financial performance, the conditions in the life sciences industry, the economy in general, the stock price performance and volatility of comparable public companies, and the lack of liquidity of the Company's common stock. Since 2022 the Company has used a comparative peer group for determining the expected volatility rate used in the calculation of fair value. Because the Company's stock has not been publicly traded for a sufficiently long period of time, the expected volatility rate is based on a review of the historical volatilities, over a period of time equivalent to the expected life of the instrument being valued, of similarly positioned public companies within the Company's industry.

The Company estimated the fair value of share-based payment awards using the Black-Scholes options valuation model. The fair value of share-based payment awards is being amortized on a straight-line basis over the requisite service period of the awards. The fair value of share-based payment awards was estimated on the date of grant using the following assumptions:

Expected Term: The Company uses the simplified method to calculate expected term described in the Securities and Exchange Commission’s Staff Accounting Bulletin No. 107, which takes into account vesting term and expiration date of the options.

Volatility: Volatility is based on an average of the historical volatilities of comparable publicly traded companies for the expected term.

Risk Free Interest Rate: The risk-free rate is based on the U.S. Treasury yields in effect at the time of grant for periods corresponding with the expected term of the option.

Dividend Yield: The Company has never declared or paid any cash dividends and does not plan to pay cash dividends in the foreseeable future, and therefore, used an expected dividend yield of zero in the valuation model.

No income tax benefits have been recognized relating to stock-based compensation expenses and no tax benefits have been realized from exercised stock options.

The weighted-average grant date fair value per share of stock options granted in 2025 and 2024 was $2.82 and $8.33, respectively. The aggregate intrinsic value of options outstanding and options vested and exercisable as of December 31, 2025 and 2024 is calculated based on the difference between the exercise price and the current fair value of our common stock. As of December 31, 2025 and 2024 the aggregate intrinsic value of options outstanding was $0 thousand and $10 thousand, respectively, and for vested and exercisable options was $0 thousand and $2 thousand. respectively.

Restricted Stock Awards

The following table summarizes the restricted stock award activity for the year ended December 31, 2025:

The fair value of restricted stock awards vested during the years ended December 31, 2025 and 2024, was $0 and $8 thousand. There is no remaining expense to be recognized in connection with restricted stock awards.

Restricted Stock Units

The following table sets forth the status of the Company's non-vested restricted common stock units issued to employees:

The fair value of restricted stock units granted during the years ended December 31, 2025 and 2024, was $406 thousand and $170 thousand, respectively. Stock-based compensation expense related to restricted stock units was $232 thousand and $2 thousand for the years ended December 31, 2025 and 2024, respectively. As of December 31, 2025, there was $316 thousand of remaining expense, which is expected to be amortized over 3.13 years.

In May 2025, the Company’s Board of Directors approved the award of certain bonus payments related to performance in 2024, to be paid in the form of restricted stock units once certain milestones have been achieved. The milestones were achieved, and the restricted stock units were issued and vested in the third quarter.

Total Stock-Based Compensation

Total stock-based compensation recorded in the condensed statements of operations is allocated as follows (in thousands):