Equity Incentive Plan

In March 2024, the Company’s board of directors adopted, and the Company’s stockholders approved, the 2024 Incentive Award Plan (the Plan), which became effective in connection with the IPO and has a term of ten years. As of June 30, 2026, a total of 5,068,078 shares of common stock were authorized for issuance under the Plan, which includes a January 1, 2026 increase of 1,120,362 shares, pursuant to the evergreen provision of the Plan. See Note 10 to the audited financial statements included in the Company’s 2025 10-K for a description of the evergreen provision of the Plan. On June 30, 2026, 2,724,148 of these shares were available for grant under the Plan.

Prior to the adoption of the Plan, the Company had awarded common stock options under the 2018 Equity Incentive Plan (as amended, the Predecessor Plan). Under the provisions of the Plan, the shares subject to awards issued under the Predecessor Plan that were outstanding as of March 27, 2024, the effective date of the Plan, and that are subsequently cancelled or forfeited, will become available for issuance under, and will increase the number of shares that may be issued under, the Plan.

Repricing of Outstanding Options

In August 2024, the compensation committee of the Company’s board of directors, as administrator of the Plan and the Predecessor Plan, approved an option repricing (2024 Repricing), which was effective on August 19, 2024 (the Repricing Effective Date). The repricing applied to options to purchase up to an aggregate of 3,484,346 shares of the Company’s common stock with an exercise price per share in excess of the closing price per share of the Company’s common stock on the Repricing Effective Date, held by eligible employees of the Company that were granted under the Plan or the Predecessor Plan and were outstanding as of the Repricing Effective Date (the Repriced Options). As of June 30, 2026, Repriced Options to purchase up to an aggregate of 2,208,476 shares of the Company’s common stock remained outstanding. See Note 10 to the audited financial statements included in the Company’s 2025 10-K for a description of the 2024 Repricing.

Option Modifications in Connection with the Merger

On June 22, 2026, in connection with the entry into the Merger Agreement (see Note 1 — Organization and Basis of Presentation), the Company amended all outstanding stock options granted under the Plan and the Predecessor Plan. The amendment (i) accelerated the vesting of all unvested options such that they became fully vested and exercisable as of June 22, 2026, (ii) extended the post-termination exercise period of the options until the later of (A) March 31, 2027 or, if the closing of the Merger occurs prior to that date, the date three months following the closing of the Merger, and (B) such later date provided in the applicable option agreement, and (iii) accelerated the premium end date applicable to the Repriced Options under the 2024 Repricing to June 22, 2026. The amendment affected options to purchase 5,945,008 shares of common stock held by 48 holders.

The Company accounted for the amendment as a modification under ASC 718 and recognized $2.0 million of stock-based compensation expense in connection with the amendment during the three and six months ended June 30, 2026, of which $1.5 million was recorded in general and administrative expense and $0.5 million was recorded in research and development expense. Total incremental compensation cost resulting from the modification was $0.4 million. The remainder consists of previously unrecognized compensation cost accelerated by the amendment, net of compensation cost previously recognized for options that were not expected to vest under their original terms, and of compensation cost measured at the modification-date fair value of those options. Fair values were estimated using a Black-Scholes option-pricing model with the following weighted-average assumptions as of the modification date: expected term of 0.8 years, expected volatility of 98.8%, risk-free interest rate of 4.0%, and expected dividend yield of 0%.

Stock Options

Aggregate intrinsic value in the above table is the difference between the estimated fair value of the Company’s common stock as of either June 30, 2026 or December 31, 2025, and the exercise price of stock options that had exercise prices below that value.

For the Repriced Options, the weighted-average prices and intrinsic value information in the table above is calculated based on the exercise price per share that applied immediately prior to the Repricing Effective Date.

During the six months ended June 30, 2026, the total intrinsic value of stock options exercised was approximately $14,000. No options were exercised during the six months ended June 30, 2025.

Employee Stock Purchase Plan

The Company maintains the 2024 Employee Stock Purchase Plan (the ESPP). As of June 30, 2026, 492,641 shares of common stock were available for issuance under the ESPP. The Company issued and sold 34,610 and 85,568 shares under the ESPP during the six months ended June 30, 2026 and 2025, respectively.

As of June 30, 2026, unrecognized compensation cost related to the ESPP was approximately $0.3 million. In connection with the Merger, the Company has suspended the ESPP and halted participant payroll deductions, and expects that a substantial portion of this cost will not be recognized.

Stock-Based Compensation Expense

As of June 30, 2026, there was no unrecognized compensation cost related to outstanding stock options, as the vesting of all outstanding options was accelerated in full on June 22, 2026 in connection with the Merger.

The weighted-average grant date per share fair value of options granted during the three months ended June 30, 2026 and 2025 were $1.12 and $0.89, respectively, and the weighted-average grant date per share fair value of options granted during the six months ended June 30, 2026 and 2025 were $1.05 and $1.89, respectively.