Stock-Based Compensation | . Stock-Based Compensation Equity Incentive Plan In February 2019, the Company adopted its 2019 Equity Incentive Plan (the “2019 Plan”). The 2019 Plan provided for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards and restricted stock units to employees, directors or consultants of the Company. The 2019 Plan provided that the maximum aggregate number of shares of the Company’s common stock reserved and available for issuance under the 2019 Plan was 6,198,493 . In October 2021, the 2019 Plan was terminated as to new awards and the Company’s board of directors adopted, and the Company’s stockholders approved, the 2021 Equity Incentive Plan (the “2021 Plan”), which became effective on October 19, 2021. The 2021 Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock, restricted stock units and performance awards to employees, directors or consultants of the Company. The number of common shares available for issuance under the 2021 Plan is 5,612,000 shares of common stock plus any common shares subject to stock options, restricted stock units or similar awards granted under the 2019 Plan that expire, are forfeited or otherwise terminate without having been exercised in full, are tendered to or withheld by the Company for payment of an exercise price or for tax withholding obligations or are forfeited to or repurchased by the Company due to failure to vest, with the maximum number of common shares to be added to the 2021 Plan equal to 4,978,561 common shares. Additionally, shares available for issuance under the 2021 Plan increase on the first day of each fiscal year, beginning with the Company’s 2023 fiscal year, equal to the lesser of 5,102,000 common shares, 5 % of the outstanding common shares on the last day of the immediately preceding fiscal year, or such number of common shares determined by the board of directors. Options granted under the 2019 Plan and 2021 Plan (the "Plans") generally vest over a period of between 2 and 4 years and expire 10 years from grant date. As of March 31, 2022 and December 31, 2021, the Company had 5,635,119 and 5,612,000 shares, respectively, authorized for issuance under the Plans, and 2,397,610 and 3,799,570 shares, respectively, remained available for grant. Total share-based compensation expense related to share-based awards was comprised of the following (in thousands): Three Months Ended March 31, 2022 2021 Research and development $ 1,195 $ 49 General and administrative 2,249 31 Total $ 3,444 $ 80 Stock Options The following table summarizes stock option activity for the three months ended March 31, 2022: Weighted Weighted Average Average Remaining Aggregate Number Exercise Contractual Intrinsic of Shares Price Term Value (in years) (in thousands) Outstanding as of December 31, 2021 6,010,490 $ 6.83 9.27 $ 78,630 Granted 1,463,350 13.15 Exercised ( 298,414 ) 0.29 Forfeited and cancelled ( 61,390 ) 9.43 Outstanding as of March 31, 2022 7,114,036 $ 8.38 9.25 $ 41,072 Options vested and expected to vest as of March 31, 2022 7,114,036 $ 8.38 9.25 $ 41,072 Options exercisable as of March 31, 2022 1,242,225 $ 3.00 8.21 $ 13,408 The weighted average grant date fair value of stock options granted during the three months ended March 31, 2022 and 2021 was $ 8.78 and $ 2.15 per share, respectively. The intrinsic value of a stock option or restricted award is the difference between the market price of the common stock at measurement date and the exercise price of the option. The total intrinsic value of stock options exercised during the three months ended March 31, 2022 was $ 3.6 million. There were no stock options exercised during the three months ended March 31, 2021. The fair value of each option award is estimated on the date of grant using the Black-Scholes model. The following assumptions were used in the Black-Scholes option pricing model to estimate the fair value of stock options granted to employees under the Company’s Plan during the periods presented: Three Months Ended March 31, 2022 2021 Risk-free interest rate 1.6 % - 2.3 % 0.9 % Expected volatility 75.0 % 80.0 % Expected term (in years) 6.0 - 10.0 3.1 - 4.9 Expected dividend yield — — Stock-based compensation expense related to stock options was $ 2.7 million for the three months ended March 31, 2022, and an immaterial amount for the three months ended March 31, 2021. As of March 31, 2022, unrecognized stock-based compensation was $ 34.7 million which is expected to be recognized over the weighted average period of 3.0 years. Restricted Stock Awards The Company grants restricted stock awards pursuant to the Plans. Restricted stock awards generally vest over a period of 3 years. Upon the termination of service of a restricted stockholder, the Company has the option to repurchase any unvested shares and based on this, restricted stock awards are not included in outstanding common stock until fully vested. During the three months ended March 31, 2022, no shares were repurchased. During the year ended December 31, 2021, the Company repurchased 9,079 shares. The following table summarizes restricted stock award activity for the three months ended March 31, 2022: Weighted Average Grant Date Number Fair Value of Shares Per Share Unvested balance as of December 31, 2021 117,872 $ 2.80 Vested ( 22,576 ) 0.10 Unvested balance as of March 31, 2022 95,296 $ 3.44 The Company records a liability for unvested restricted awards subject to repurchase and reduces the liability as the underlying shares vest. The liability was immaterial as of March 31, 2022 and December 31, 2021. The total fair value of restricted stock awards vested during the three months ended March 31, 2022 and 2021 was immaterial. As of March 31, 2022, there was approximately $ 0.2 million of unrecognized stock-based compensation cost pertaining restricted stock awards that will be recognized over a weighted average period of 2.1 years. Restricted Stock Units The Company grants restricted stock units pursuant to the Plans and satisfies such grants through the issuance of new shares as they vest. Restricted stock units generally vest over a period of 4 years. There were no changes to restricted stock units during the three months ended March 31, 2022. As of March 31, 2022, there was approximately $ 9.2 million of unrecognized stock-based compensation cost pertaining to restricted stock units that will be recognized over a weighted average period of 3.7 years. Employee Stock Purchase Plan In October 2021, the board of directors and stockholders approved the 2021 Employee Stock Purchase Plan (“ESPP”) which became effective on October 19, 2021. The maximum number of shares of common stock that will be made available for sale under the ESPP is equal to 510,000 shares of common stock. In addition, the number of shares of common stock available for issuance under the ESPP will be increased on the first day of each fiscal year, beginning with fiscal year 2023, in an amount equal to the lesser of 1,020,000 shares of common stock, 1 % of the outstanding shares of common stock on the last day of the immediately preceding fiscal year or such number of common shares determined by the board of directors. Participating employees purchase stock under the ESPP at a price equal to the lower of 85 % of the closing price on the applicable offering commencement date or 85 % of the closing price on the applicable offering termination date. The ESPP provides for two offering periods of six months ’ duration with purchase periods terminating on either May 15 or November 15. Contributions under the ESPP are limited to a maximum of 15 % of an employee’s eligible compensation and a maximum of 3,000 shares per year. Total stock-based compensation expense recognized related to the ESPP for the three months ended March 31, 2022 was approximately $ 0.1 million. |