Equity Incentive Plans and Stock-Based Compensation | 7. Equity Incentive Plans and Stock-Based Compensation Equity Incentive Plans In September 2021, the Company's Board of Directors adopted, and its stockholders approved, the 2021 Incentive Award Plan (the 2021 Plan). Upon the adoption of the 2021 Plan, the Company restricted the grant of future equity awards under the 2020 Equity Incentive Plan (the 2020 Plan). The 2021 Plan provides for the grants of stock options and other equity-based awards to employees, non-employee directors, and consultants of the Company. A total of 5,570,000 shares of the Company’s common stock were initially reserved for issuance pursuant to the 2021 Plan, consisting of 4,537,850 shares reserved under the 2021 Plan and 1,032,150 shares of the Company’s common stock that remained available for issuance under the 2020 Plan. The 2021 Plan share reserve increased by the number of shares under the 2020 Plan that were repurchased, forfeited, expired or cancelled after the effective date of the 2021 Plan. In addition, the number of shares of the Company’s common stock available for issuance under the 2021 Plan automatically increases on the first day of each fiscal year, beginning with the Company’s 2022 fiscal year, in an amount equal to the lesser of (1) 5 % of the outstanding shares of the Company’s common stock on the last day of the immediately preceding fiscal year, or (2) such smaller amount as determined by the Company’s Board of Directors. On January 1, 2024, the shares available for grant under the 2021 Plan were increased by 2,154,952 . As of June 30, 2024, 5,169,104 shares were available for future grant under the 2021 Plan. A summary of the Company’s stock option activity for the period ended June 30, 2024 was as follows (in thousands, except share and per share data and years): Options Weighted-Average Weighted-Average Aggregate Outstanding at December 31, 2023 8,276,442 $ 10.07 8.3 $ 40,420 Granted 680,550 $ 17.52 Exercised ( 339,167 ) $ 2.33 Cancelled ( 17,389 ) $ 8.26 Outstanding at June 30, 2024 8,600,436 $ 10.97 8.1 $ 50,366 Exercisable at June 30, 2024 3,896,013 $ 9.19 7.3 $ 30,787 Vested and expected to vest as of June 30, 2024 8,600,436 $ 10.97 8.1 $ 50,366 Stock-Based Compensation Expense The Company estimated the fair value of stock options using the Black-Scholes valuation model. The Company accounts for forfeitures of options when they occur. Previously recognized compensation expense for an award is reversed in the period that the award is forfeited. The fair value of stock options was estimated using the following assumptions: Six Months Ended 2024 2023 Risk-free rate of interest 4.2 - 4.6 % 3.5 - 4.2 % Expected term (years) 5.3 - 6.1 5.2 - 6.1 Expected stock price volatility 87.8 - 93.5 % 88.6 - 89.7 % Dividend yield — — Stock-based compensation expense recognized for all equity awards has been reported in the condensed statements of operations and comprehensive loss as follows (in thousands): Three Months Ended Six Months Ended 2024 2023 2024 2023 Research and development expense $ 2,658 $ 1,478 $ 5,133 $ 2,937 General and administrative expense 1,753 1,051 3,393 2,025 Total $ 4,411 $ 2,529 $ 8,526 $ 4,962 The weighted-average grant date fair value of options granted for the six months ended June 30, 2024 and 2023 was $ 13.41 a nd $ 7.65 per share, respectively. For the six months ended June 30, 2024 and 2023, forfeitures resulting in the reversal of compensation expenses were immaterial. As of June 30, 2024, the unrecognized compensation cost related to outstanding employee and nonemployee options was $ 41.3 million, and is expected to be recognized as expense over a weighted-average period of approximately 2.1 years. Employee Stock Purchase Plan In September 2021, the Company’s Board of Directors and stockholders approved and adopted the 2021 Employee Stock Purchase Plan (ESPP). The ESPP became effective on the business day immediately prior to the effective date of the Company’s first registration statement. A total of 380,000 shares of the Company’s common stock were initially reserved for issuance pursuant to the ESPP. In addition, the number of shares of the Company’s common stock available for issuance under the ESPP will automatically increase on the first day of each fiscal year, beginning with the Company’s 2022 fiscal year, in an amount equal to the lesser of (1) 1 % of the outstanding shares of the Company’s common stock on the last day of the immediately preceding fiscal year, or (2) such smaller amount as determined by the Company’s Board of Directors. On January 1, 2024, the number of shares reserved for issuance under the ESPP was increased by 430,990 shares. The ESPP permits eligible employees who elect to participate in an offering under the ESPP to have up to 15 % of their eligible earnings withheld, subject to certain limitations, to purchase shares of common stock pursuant to the ESPP. The price of common stock purchased under the ESPP is equal to 85 % of the lower of the fair market value of the common stock at the commencement date of each offering period or the relevant date of purchase. Each offering period is 24 months, with new offering periods commencing every six months on or about the dates of March 15 and September 15 of each year. During the six months ended June 30, 2024 and 2023, the Company issued 43,692 and 32,442 shares, respectively, of common stock in connection with the ESPP . As of June 30, 2024, there were 1,516,697 shares available for future purchase under the ESPP. The Company recognized compensation expense of $ 0.1 million and $ 0.2 million for the three months ended June 30, 2024 and 2023 , respectively, and $ 0.2 million and $ 0.3 million for the six months ended June 30, 2024 and 2023, respectively, related to the ESPP. As of June 30, 2024, the remaining unrecognized compensation expense related to the ESPP was $ 0.2 million, and is expected to be recognized as expense over a weighted-average period of approximately 0.8 years. |