Stock-based Compensation -Schedule of Stock Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended
Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2022 $ / shares
Options
Outstanding as of December 31, 2022 (in shares) \| shares	3,356,937
Sesen Bio options assumed in the Merger (in shares) \| shares	765,223
Exercised (in shares) \| shares	(49,770)
Granted (in shares) \| shares	2,805,152
Forfeited (in shares) \| shares	(87,275)
Expired (in shares) \| shares	(274,922)
Outstanding as of September 30, 2023 (in shares) \| shares	6,515,345
Exercisable as of September 30, 2023 (in shares) \| shares	3,038,911
Vested and expected to vest at September 30, 2023 (in shares) \| shares	6,515,345
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)	1.72
Granted (in USD per share)	7.14
Forfeited (in USD per share)	4.70
Expired (in USD per share)	23.52
Outstanding as of September 30, 2023 (in USD per share)	6.28
Exercisable as of September 30, 2023 (in USD per share)	6.71
Vested and expected to vest at September 30, 2023 (in USD per share)	6.28
Share based compensation arrangement by share based payment award options grants in period weighted average grant date fair value (in USD per share)	$ 4.42	$ 1.46
Weighted average remaining contractual term (years)
Outstanding as of September 30, 2023	7 years 3 months 18 days
Exercisable as of September 30, 2023	5 years 21 days
Vested and expected to vest at September 30, 2023	7 years 3 months 18 days
Aggregate Intrinsic Value
Exercised \| $	$ 190
Outstanding as of September 30, 2023 \| $	10,191
Exercisable as of September 30, 2023 \| $	8,068
Vested and expected to vest at September 30, 2023 \| $	$ 10,191

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Gross number of share options (or share units) assumed in a merger during the period.

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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.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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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.

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Number of fully vested and expected to vest exercisable options that may be converted into shares under option plan. 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.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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