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Stock-based Compensation -Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022
Options |  |
Outstanding as of December 31, 2022 (in shares) | 3,356,937 |
Sesen Bio options assumed in the Merger (in shares) | 765,223 |
Exercised (in shares) | (128,716) |
Granted (in shares) | 2,984,152 |
Forfeited (in shares) | (114,454) |
Expired (in shares) | (839,772) |
Outstanding as of September 30, 2023 (in shares) | 6,023,370 | 3,356,937
Exercisable as of September 30, 2023 (in shares) | 2,516,594 |
Vested and expected to vest at September 30, 2023 (in shares) | 6,023,370 |
Weighted average exercise price |  |
Outstanding as of December 31, 2022 (in USD per share) | $ 1.01 |
Sesen Bio options assumed in the Merger (in USD per share) | 27.94 |
Exercised (in USD per share) | 1.29 |
Granted (in USD per share) | 6.93 |
Forfeited (in USD per share) | 5.80 |
Expired (in USD per share) | 29.48 |
Outstanding as of September 30, 2023 (in USD per share) | 3.94 | $ 1.01
Exercisable as of September 30, 2023 (in USD per share) | 1.16 |
Vested and expected to vest at September 30, 2023 (in USD per share) | 3.94 |
Share based compensation arrangement by share based payment award options grants in period weighted average grant date fair value (in USD per share) | $ 4.29 | $ 1.46
Weighted average remaining contractual term (years) |  |
Outstanding as of September 30, 2023 | 7 years 9 months 18 days |
Exercisable as of September 30, 2023 | 6 years |
Vested and expected to vest at September 30, 2023 | 7 years 9 months 18 days |
Aggregate Intrinsic Value |  |
Exercised | $ 134 |
Outstanding as of September 30, 2023 | 5,929 |
Exercisable as of September 30, 2023 | 4,950 |
Vested and expected to vest at September 30, 2023 | $ 5,929 |

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- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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- Definition The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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- Definition Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(04) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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- Definition Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (e)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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