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Stock-Based Compensation | 6 Months Ended
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Jun. 30, 2026
Share-Based Payment Arrangement [Abstract] |
Stock-Based Compensation | 8. Stock-Based Compensation 2019 and 2021 Equity Incentive Plans The Company has outstanding awards under its 2019 Equity Incentive Plan (the 2019 Plan), but is no longer granting awards under this plan. The Company’s 2021 Equity Incentive Plan (the 2021 Plan and, together with the 2019 Plan, the Plans) provides for the grant of incentive stock options, non-statutory stock options, restricted stock awards, restricted stock units (RSUs), stock appreciation rights and other stock-based awards to the Company’s employees, officers, directors and consultants. Any shares that are returned under the 2019 Plan as a result of cancellation or forfeiture become available for grant under the 2021 Plan. Further, the number of shares of common stock reserved for issuance under the 2021 Plan automatically increases on January 1 of each year continuing through and including January 1, 2031, by 5% of the total number of shares of common stock outstanding on December 31 of the immediately preceding calendar year, or a lesser number of shares determined by the Company’s board of directors. The number of shares reserved for issuance under the 2021 Plan was increased by 2,388,316 shares effective as of January 1, 2026 in accordance with the provisions of the 2021 Plan described abov e. On June 5, 2026, the Company’s shareholders approved an amendment to the 2021 Plan to amend the provision providing for an automatic share pool increase to include pre-funded warrants in the calculation of the annual increase. As a result of the amendment, the next automatic annual share pool increase will come into effect on January 1, 2027 and it will be equal to the lesser of (I) 5% of the sum of (1) the number of outstanding shares of common stock and (2) the number of shares of the Company's common stock subject to pre-funded warrants, each as of the immediately preceding December 31, and (II) an amount determined by the board of directors. As of June 30, 2026, 3,225,667 shares remained available for future grant under the 2021 Plan. Under the terms of the 2021 Plan, options are granted at an exercise price no less than fair value of the Company’s common stock on the grant date, except in certain cases related to significant corporate transactions. Options expire no later than ten years from the date of the grant. 2025 Inducement Plan In March 2025, the Company’s board of directors adopted the 2025 Inducement Plan (the Inducement Plan), pursuant to which the Company may grant nonstatutory stock options, stock appreciation rights, restricted stock, RSUs and other stock-based awards with respect to an aggregate of 1,250,000 shares of its common stock. Awards under the Inducement Plan may only be granted to new employees who were not previously an employee or director of the Company or are commencing employment with the Company following a bona fide period of non-employment, in either case, as an inducement material to the individual’s entering into employment with the Company in accordance with the requirements of Nasdaq Stock Market Rule 5635(c)(4). On September 30, 2025, the Company’s board of directors approved an amendment to the Inducement Plan to increase the number of shares of common stock authorized for issuance under the Inducement Plan by 750,000 shares. As of June 30, 2026, 145,834 shares were available for issuance under the Inducement Plan. Employee Stock Purchase Plan The Company’s 2021 Employee Stock Purchase Plan (the ESPP) allows employees, including executive officers, to contribute up to 15% of their earnings, subject to certain limitations, for the purchase of the Company’s common stock at a price per share equal to the lower of (a) 85% of the fair market value of a share of common stock on the first day of the offering period, or (b) 85% of the fair market value of a share of common stock on the last day of the offering period. The number of shares of common stock reserved for issuance under the ESPP automatically increases on January 1 of each calendar year through and including January 1, 2031, by the lesser of (1) 1% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year or (2) a number of shares determined by the Company’s board of directors. Shares subject to purchase rights granted under the ESPP that terminate without having been exercised in full will not reduce the number of shares available for issuance under the ESPP. The number of shares reserved for issuance under the ESPP was increased by 477,663 shares effective as of January 1, 2026 in accordance with the provisions of the ESPP described above. As of June 30, 2026, 20,359 shares had been purchased under the ESPP and 2,194,083 shares remained available for issuance under the ESPP. Stock Option Valuation The fair value of stock option grants is estimated on the date of grant using the Black Scholes option pricing model. Volatility is estimated based on the historical and implied volatilities of comparable publicly traded companies as the Company does not have sufficient history of trading in its common stock. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. The relevant data used to determine the fair value of the stock options during the three and six months ended June 30, 2026 and 2025 is as follows:
|  | Three Months Ended June 30, |  |  | Six Months Ended June 30, |
|  | 2026 |  |  | 2025 |  |  | 2026 |  |  | 2025 |
Expected term (in years) |  |  | 5.9 |  |  |  | 6.0 |  |  |  | 6.0 |  |  |  | 6.0 |
Expected volatility |  |  | 93.1 | % |  |  | 100.7 | % |  |  | 97.5 | % |  |  | 104.3 | %
Risk-free interest rate |  |  | 4.2 | % |  |  | 4.1 | % |  |  | 3.9 | % |  |  | 4.4 | %
Expected dividend yield |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |
Stock Option Activity Outstanding stock options consist of option grants with service-based vesting conditions, typically 25% on the first anniversary of the grant date with the remainder vesting monthly over the following three years. The activity for the stock options is as follows:
|  |  |  |  | Weighted |  |  | Weighted |  |  |  |
|  |  |  |  | Average |  |  | Average |  |  | Aggregate |
|  | Number of |  |  | Exercise |  |  | Contractual |  |  | Intrinsic |
|  | Shares |  |  | Price |  |  | Term |  |  | Value |
|  |  |  |  |  |  |  | (in years) |  |  | (in thousands) |
Outstanding as of December 31, 2025 |  |  | 6,427,777 |  |  | $ | 2.81 |  |  |  | 9.05 |  |  | $ | 11,727 |
Options granted |  |  | 2,926,074 |  |  |  | 5.83 |  |  |  |  |  |  |
Options exercised |  |  | (97,720 | ) |  |  | 2.66 |  |  |  |  |  |  |
Options forfeited |  |  | (784,866 | ) |  |  | 4.14 |  |  |  |  |  |  |
Outstanding as of June 30, 2026 |  |  | 8,471,265 |  |  | $ | 3.73 |  |  |  | 8.70 |  |  | $ | 78,899 |
Vested and expected to vest as of June 30, 2026 |  |  | 8,471,265 |  |  | $ | 3.73 |  |  |  | 8.70 |  |  | $ | 78,899 |
Options exercisable as of June 30, 2026 |  |  | 1,925,199 |  |  | $ | 3.42 |  |  |  | 7.08 |  |  | $ | 18,512 |
The aggregate intrinsic value disclosed in the above table is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had strike prices lower than the fair value of the Company’s common stock. The weighted-average grant date fair value of stock options granted during the six months ended June 30, 2026 and 2025 was $4.58 and $1.35 per share, respectively. Restricted Stock Units The Company has outstanding RSUs with service-based vesting conditions and RSUs with performance-based vesting conditions. The activity for RSUs is as follows:
|  | Shares |  |  | Weighted Average Grant Date Fair Value |
Unvested at December 31, 2025 |  |  | 207,897 |  |  | $ | 7.50 |
Granted |  |  | 441 |  |  |  | 5.67 |
Vested |  |  | (70,838 | ) |  |  | 7.44 |
Unvested at June 30, 2026 |  |  | 137,500 |  |  | $ | 7.53 |
Stock-Based Compensation The following table sets forth stock-based compensation expense included in the Company’s unaudited condensed consolidated statements of operations and comprehensive loss (in thousands):
|  | Three Months Ended June 30, |  |  | Six Months Ended June 30, |
|  | 2026 |  |  | 2025 |  |  | 2026 |  |  | 2025 |
Research and development expenses |  | $ | 333 |  |  | $ | 521 |  |  | $ | 905 |  |  | $ | 1,427 |
General and administrative expenses |  |  | 1,148 |  |  |  | 492 |  |  |  | 2,181 |  |  |  | 1,608 |
Total stock-based compensation expense |  | $ | 1,481 |  |  | $ | 1,013 |  |  | $ | 3,086 |  |  | $ | 3,035 |
As of June 30, 2026, ther e was $19.5 million of total unrecognized compensation cost related to unvested awards expected to vest, which is expected to be recognized over a weighted average period of 2.9 years.

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