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Stock-Based Compensation (Tables) | 3 Months Ended
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Mar. 31, 2023
Stock-Based Compensation |
Schedule of stock option activity | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | Weighted | ​ | Weighted
​ | ​ | ​ | ​ | Average | ​ | Average
​ | ​ | ​ | ​ | Exercise | ​ | Remaining
​ | ​ | ​ | ​ | Price | ​ | Contractual
​ |  | Shares |  | Per Share |  | Term (In Years)
Options outstanding at December 31, 2022 |  | 5,085,662 | ​ | $ | 29.26 | ​ | 7.9
Granted |  | 26,900 | ​ | $ | 43.17 | ​ | ​
Exercised |  | (37,492) | ​ | $ | 15.18 | ​ | ​
Canceled |  | (107,306) | ​ | $ | 20.95 | ​ | ​
Options outstanding at March 31, 2023 |  | 4,967,764 | ​ | $ | 29.62 | ​ | 7.6
Options vested and expected to vest at March 31, 2023 |  | 4,884,568 | ​ | $ | 29.72 | ​ | 7.6
Options exercisable at March 31, 2023 |  | 2,273,841 | ​ | $ | 38.18 | ​ | 6.4
Shares available for grant under the 2021 Plan |  | 1,918,374 | ​ | ​ | ​ | ​ | ​
​
Schedule of stock-based compensation expense | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Three months ended March 31,
​ |  | 2023 |  | 2022
​ | ​ | (In thousands)
Research and development | ​ | $ | 2,162 | ​ | $ | 1,614
General and administrative | ​ |  | 2,178 | ​ |  | 1,539
Total stock-based compensation expense | ​ | $ | 4,340 | ​ | $ | 3,153
​
Schedule of assumptions used for the fair value of employee stock options granted | ​
​ | ​ | ​ | ​ | ​
​ | ​ | Three months ended March 31,
|  | 2023 |  | 2022
Expected stock price volatility |  | 92% | ​ | 91 - 97%
Expected option term |  | 6.0 Years | ​ | 6.0 Years
Risk-free interest rate |  | 3.7 - 4.0% | ​ | 1.7 - 1.9%
Expected dividend yield |  | None | ​ | None

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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 https://asc.fasb.org/extlink&oid=128089324&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 https://asc.fasb.org/extlink&oid=128089324&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 https://asc.fasb.org/extlink&oid=128089324&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 https://asc.fasb.org/extlink&oid=128089324&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 https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901 + Details
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