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Stock-based Compensation (Tables) | 12 Months Ended
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Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Summary of Stock Option Activity | A summary of the Company’s stock option activity under the 2021 Plan and 2018 Plan is as follows (in thousands, except share and per share data and years):
|  |  |  |  |  |  |  | Weighted- |  |  |  |
|  |  |  |  | Weighted- |  |  | average remaining |  |  | Aggregate |
|  |  |  |  | average |  |  | contractual |  |  | intrinsic |
|  | Shares |  |  | exercise price |  |  | term (years) |  |  | value |
Outstanding at December 31, 2020 |  |  | 6,541,422 |  |  | $ | 0.98 |  |  |  | 9.23 |  |  | $ | 15,571 |
Granted |  |  | 8,320,187 |  |  |  | 5.93 |  |  |  |  |  |  |
Exercised |  |  | (736,200 | ) |  |  | 1.88 |  |  |  |  |  |  |
Canceled |  |  | (307,197 | ) |  |  | 2.97 |  |  |  |  |  |  |
Outstanding at December 31, 2021 |  |  | 13,818,212 |  |  | $ | 3.87 |  |  |  | 8.82 |  |  | $ | 163,264 |
Options exercisable at December 31, 2021 |  |  | 3,161,831 |  |  | $ | 1.63 |  |  |  | 8.29 |  |  | $ | 44,119 |
Summary of Restricted Stock Activity | The summary of the Company’s restricted stock activity during the year ended December 31, 2021 is as follows:
|  | Number of |  |  | Weighted- |
|  | restricted |  |  | average |
|  | stock shares |  |  | grant date |
|  | outstanding |  |  | fair Value |
Nonvested at December 31, 2020 |  |  | 557,731 |  |  | $ | 0.001 |
Vested |  |  | (344,790 | ) |  |  | 0.001 |
Nonvested at December 31, 2021 |  |  | 212,941 |  |  | $ | 0.001 |
Schedule of Stock-based Compensation Expense | The allocation of stock-based compensation for all stock awards was as follows (in thousands):
|  | Year Ended December 31, |
|  | 2021 |  |  | 2020 |
Research and development |  | $ | 4,957 |  |  | $ | 348 |
General and administrative |  |  | 3,374 |  |  |  | 449 |
Total |  | $ | 8,331 |  |  | $ | 797 |
Summary of Common Stock Reserved for Future Issuance | Common stock reserved for future issuance consisted of the following as of December 31, 2021 and 2020:
|  | December 31, |  |  | December 31, |
|  | 2021 |  |  | 2020 |
Conversion of preferred stock outstanding |  |  | — |  |  |  | 57,987,216 |
Conversion of preferred stock in future issuance (B-2) |  |  | — |  |  |  | 10,979,319 |
Stock options issued and outstanding |  |  | 13,818,212 |  |  |  | 6,541,422 |
Awards available for future grant |  |  | 14,699,430 |  |  |  | 2,314,746 |
Shares available for purchase under the ESPP |  |  | 1,168,013 |  |  |  | — |
Total |  |  | 29,685,655 |  |  |  | 77,822,703 |
Stock Options |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Assumptions used to Determine Fair Value of Stock Option Grants and Stock to be Purchased under ESPP | The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee and nonemployee stock option grants were as follows:
|  | Year Ended December 31,
|  | 2021 |  | 2020
Risk-free interest rate |  | 0.59%-1.34% |  | 0.37%-1.22%
Expected volatility |  | 81.93%-85.35% |  | 74.72%-77.81%
Expected term (in years) |  | 6.08 |  | 6.02-6.25
Expected dividend yield |  | --% |  | --%
ESPP |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Assumptions used to Determine Fair Value of Stock Option Grants and Stock to be Purchased under ESPP | The assumptions used in the Black-Scholes option pricing model to determine the fair value of the stock to be purchased under the ESPP were as follows:
|  | Year Ended December 31,
|  | 2021 |  | 2020(1)
Risk-free interest rate |  | 0.05%-0.64% |  | --%
Expected volatility |  | 70.99%-91.69% |  | --%
Expected term (in years) |  | 0.39-2.00 |  | --
Expected dividend yield |  | --% |  | --%
The ESPP was not in effect until 2021

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- Definition Tabular disclosure of allocation of amount expensed and capitalized for award under share-based payment arrangement to statement of income or comprehensive income and statement of financial position. Includes, but is not limited to, corresponding line item in financial statement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -URI http://asc.fasb.org/extlink&oid=122041274&loc=d3e301413-122809 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901 + Details
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- Definition Tabular disclosure of the number and weighted-average grant date fair value for restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock units that were granted, vested, or forfeited during the year. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Tabular disclosure for stock option plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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