Stockholders' Equity and Stock-Based Compensation | 8. Stockholders’ Equity and Stock-Based Compensation As of March 31, 2024, there were 2,485,870 shares available for future issuance under the 2020 Equity Incentive Plan and 770,371 shares available for future issuance under the 2022 Inducement Equity Incentive Plan. The 2020 Equity Incentive Plan provides for the grants of stock options and other equity-based awards to employees, non-employee directors and consultants of the Company. The 2022 Inducement Equity Incentive Plan provides for the grants of equity-based awards to individuals not previously employees or non-employee directors of the Company. The table below summarizes the total stock-based compensation expense included in the Company’s statements of operations and comprehensive loss for the periods presented (in thousands): Three Months Ended 2024 2023 Research and development $ 2,145 $ 1,475 General and administrative 2,813 2,139 Total stock-based compensation expense $ 4,958 $ 3,614 Stock Options On June 21, 2022, the Company filed with the SEC a Tender Offer Statement on Schedule TO defining the terms and conditions of a one-time voluntary stock option exchange of certain eligible options for its employees (the Option Exchange). On July 20, 2022, the completion date of the Option Exchange, stock options covering an aggregate of 4,406,732 sh ares of common stock were tendered by eligible employees, and the Company granted new options at an exercise price of $ 4.36 , the Company’s closing stock price on July 20, 2022, covering an aggregate of 4,406,732 shares of common stock under the 2020 Equity Incentive Plan in exchange for the tendered options. As a result of the Option Exchange, the Company will recognize incremental stock-based compensation expense of $ 3.7 million over the requisite service period of the new stock options, which is three or four years. The Company will recognize the sum of the incremental stock-based compensation expense and the remaining unrecognized compensation expense for the original awards on the modification date, over the requisite service period of the new stock options. The following table summarizes the stock option activity for the three months ended March 31, 2024: Options Weighted- Weighted- Aggregate Outstanding at December 31, 2023 8,715,529 $ 4.70 Granted 2,274,990 $ 9.20 Exercised ( 51,540 ) $ 3.86 Forfeited and cancelled ( 123,025 ) $ 6.21 Outstanding at March 31, 2024 10,815,954 $ 5.63 8.1 $ 89,201 Exercisable at March 31, 2024 4,521,533 $ 4.42 6.9 $ 43,542 The fair value of stock option awards to employees, executives, directors, and other service providers was estimated at the date of grant using the Black-Scholes-Merton option pricing model with the following assumptions: Three Months Ended 2024 2023 Risk-free interest rate 3.82 % - 4.19 % 3.45 % Expected volatility 85.97 % - 86.31 % 87.68 % Expected term (in years) 6.08 6.08 Expected dividend yield 0 % 0 % The Company recognized stock-based compensation expense related to the vesting of stock options of $ 4.1 million and $ 3.1 million during the three months ended March 31, 2024 and 2023, respectively. Total unrecognized compensation expense related to outstanding unvested stock-option awards as of March 31, 2024, was $ 40.3 million, which is expected to be recognized over a weighted-average remaining service period of 2.8 years. Restricted Stock Units The following table summarizes the restricted stock unit activity for the three months ended March 31, 2024: Number of Shares Weighted- Outstanding at December 31, 2023 330,631 $ 6.55 Granted 379,267 $ 9.20 Vested ( 3,245 ) $ 7.01 Forfeited ( 11,407 ) $ 8.27 Outstanding at March 31, 2024 695,246 $ 7.97 The Company recognized stock-based compensation expense related to the vesting of restricted stock units of $ 0.6 million and $ 0.3 million during the three months ended March 31, 2024 and 2023, respectively. Total unrecognized compensation expense related to restricted stock units as of March 31, 2024, was $ 4.8 million, which is expected to be recognized over a weighted-average remaining service period of 2.2 years. Employee Stock Purchase Plan The Company recognized stock-based compensation expense related to the Employee Stock Purchase Plan (ESPP) of $ 0.3 million and $ 0.2 million during the three months ended March 31, 2024 and 2023, respectively. Pre-funded Warrants In June 2023, the Company completed a private placement, in which it sold 9,285,710 shares of common stock together with pre-funded warrants to purchase 2,857,142 shares of common stock with an exercise price of $ 0.0001 per share. Each pre-funded warrant was immediately exercisable and will remain exercisable until exercised in full. The Company performed an assessment upon issuance of the pre-funded warrants to determine proper classification in the financial statements based on the specific terms of the pre-funded warrants. The Company determined the pre-funded warrants met all the criteria for equity classification and recorded them in additional paid-in capital. All pre-funded warrants remained outstanding as of March 31, 2024 . Net Loss per Share The following outstanding shares of potentially dilutive securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been anti-dilutive: Three Months Ended March 31, 2024 2023 Options to purchase common stock 10,815,954 8,474,399 Non-vested restricted stock units 695,246 485,942 Total 11,511,200 8,960,341 |