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Commitments and Contingencies - Additional Information (Detail) |  |  |  | 3 Months Ended | 6 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 04, 2024 ft² | Apr. 19, 2024 USD ($) ft² | Aug. 12, 2022 | Jun. 30, 2025 USD ($) | Jun. 30, 2024 USD ($) | Jun. 30, 2025 USD ($) Milestone | Jun. 30, 2024 USD ($) Milestone | Dec. 31, 2024 USD ($) | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) ft² | Dec. 31, 2021 USD ($) | Nov. 21, 2024 USD ($) | May 31, 2015 USD ($)
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Non-cancelable purchase obligations related to manufacturing |  |  |  | $ 6,600,000 |  | $ 6,600,000 |  |  |  |  |  |  |
Rental expense |  |  |  | 100,000 | $ 100,000 | 200,000 | $ 200,000 |  |  |  |  |  |
Lease liabilities |  |  |  | 803,000 |  | 803,000 |  | $ 954,000 |  |  |  |  |
ROU assets |  |  |  | 773,000 |  | $ 773,000 |  | 926,000 |  |  |  |  |
Remaining term of office lease |  |  |  |  |  | 3 years |  |  |  |  |  |  |
Debt outstanding |  |  |  | 0 |  | $ 0 |  |  |  |  |  |  |
Indemnification obligations amount |  |  |  | 0 |  | 0 |  |  |  |  |  |  |
Contingent liabilities |  |  |  | 0 |  | $ 0 |  |  |  |  |  |  |
ALS Therapy Development Foundation, Inc. License Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Fee due for milestones achieved |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,000,000
Number of Milestones Achieved | Milestone |  |  |  |  |  | 0 | 0 |  |  |  |  |  |
Remaining milestone payments for first licensed product |  |  |  | 6,000,000.0 |  | $ 6,000,000.0 |  |  |  |  |  |  |
Annual License Maintenance Fee |  |  |  |  |  |  |  | $ 100,000 | $ 100,000 | $ 100,000 | $ 100,000 |  |
ALS Therapy Development Foundation, Inc. License Agreement [Member] | Achievement of 500 Million Aggregate Sales [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Reaching of aggregate net sales |  |  |  |  |  | 500,000,000.0 |  |  |  |  |  |  |
Amount of one-time milestone payment |  |  |  | 15,000,000.0 |  | 15,000,000.0 |  |  |  |  |  |  |
ALS Therapy Development Foundation, Inc. License Agreement [Member] | Achievement of 1 Billion Aggregate Sales [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Reaching of aggregate net sales |  |  |  |  |  | 1,000,000,000.0 |  |  |  |  |  |  |
Amount of one-time milestone payment |  |  |  | 30,000,000.0 |  | 30,000,000.0 |  |  |  |  |  |  |
eGenesis, Inc. Collaboration Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Manufacturing expenses offset |  |  |  |  |  | 100,000 |  |  |  |  |  |  |
Lonza Sales AG Inc. License Agreement |  |  |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Royalties paid |  |  |  |  |  | 0 |  |  |  |  |  |  |
Maximum [Member] | ALS Therapy Development Foundation, Inc. License Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Development and regulatory milestone payments |  |  |  | $ 2,500,000 |  | $ 2,500,000 |  |  |  |  |  |  |
Irvine, California [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Area of office space | ft² |  | 5,817 |  |  |  |  |  |  |  | 5,197 |  |  |
Operating lease, term of contract |  | 38 months |  |  |  |  |  |  |  |  |  |  |
Lease expiration date |  | Jun. 30, 2027 | Dec. 31, 2024 |  |  |  |  |  |  |  |  |  |
ROU assets |  | $ 500,000 |  |  |  |  |  |  |  |  |  |  |
Burlington, Massachusetts [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Area of office space | ft² | 6,138 |  |  |  |  |  |  |  |  |  |  |  |
Operating lease, term of contract | 36 months |  |  |  |  |  |  |  |  |  |  |  |
Lease expiration date | Nov. 21, 2027 |  |  |  |  |  |  |  |  |  |  |  |
Lease liabilities |  |  |  |  |  |  |  |  |  |  |  | $ 500,000 |
ROU assets |  |  |  |  |  |  |  |  |  |  |  | $ 500,000 |

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