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v3.26.1

License and Collaborations (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2026 | Dec. 31, 2025 | Mar. 31, 2025 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2020 | Dec. 31, 2017
License And Collaboration Agreements [Line Items] |  |  |  |  |  |  |
Total revenues | $ 7 |  | $ 8 |  |  |  |
Receivable from collaboration partners | 3 | $ 11 |  |  |  |  |
Other current liabilities | 136 | 154 |  |  |  |  |
Other noncurrent liabilities | 119 | 135 |  |  |  |  |
Taiho Collaboration Agreement |  |  |  |  |  |  |
License And Collaboration Agreements [Line Items] |  |  |  |  |  |  |
Milestone payments |  |  | 19 |  |  |  |
Receivable from collaboration partners | 3 | 10 |  |  |  |  |
Other liabilities | 23 | 44 |  |  |  |  |
AstraZeneca Agreement |  |  |  |  |  |  |
License And Collaboration Agreements [Line Items] |  |  |  |  |  |  |
Milestone payments |  |  |  |  |  | $ 24 |
Development cost recorded within research and development expenses | 5 |  | 4 |  |  |  |
Other current liabilities | 17 |  |  |  |  |  |
Other noncurrent liabilities |  | 12 |  |  |  |  |
Taiho Pharmaceutical Co., Ltd | Taiho Agreement |  |  |  |  |  |  |
License And Collaboration Agreements [Line Items] |  |  |  |  |  |  |
Option period |  |  |  |  |  |  | 5 years
Non refundable and non creditable cash payments |  |  |  |  |  |  | $ 35
Payment for option exercise |  | 15 |  |  |  |  |
Royalties payable term |  |  |  |  |  |  | 10 years
Total revenues | 2 |  |  |  |  |  |
Reimbursement of research and development expense | 5 |  | 9 |  |  |  |
Taiho Pharmaceutical Co., Ltd | Taiho Agreement | Minimum |  |  |  |  |  |  |
License And Collaboration Agreements [Line Items] |  |  |  |  |  |  |
Payment for option exercise |  |  |  |  |  |  | $ 3
Taiho Pharmaceutical Co., Ltd | Taiho Agreement | Maximum |  |  |  |  |  |  |
License And Collaboration Agreements [Line Items] |  |  |  |  |  |  |
Payment for option exercise |  |  |  |  |  |  | 15
Additional clinical and regulatory milestone payments receivable |  | 172 |  |  |  |  | 130
Contingent milestone payments receivable |  | $ 145 |  |  |  |  | $ 145
STAR-221 Development Activities | Taiho Collaboration Agreement |  |  |  |  |  |  |
License And Collaboration Agreements [Line Items] |  |  |  |  |  |  |
Milestone payments |  |  |  |  | $ 28 |  |
STAR-121 Development Activities | Taiho Collaboration Agreement |  |  |  |  |  |  |
License And Collaboration Agreements [Line Items] |  |  |  |  |  |  |
Milestone payments |  |  |  | $ 26 |  |  |
Abmuno License Agreement |  |  |  |  |  |  |
License And Collaboration Agreements [Line Items] |  |  |  |  |  |  |
Additional clinical, regulatory and commercialization milestone payments | 88 |  |  |  |  |  |
Development milestone expense | 0 |  | 0 |  |  |  |
WuXi Biologics License Agreement | anti-PD-1 |  |  |  |  |  |  |
License And Collaboration Agreements [Line Items] |  |  |  |  |  |  |
Development milestone expense | 0 |  | 0 |  |  |  |
WuXi Biologics License Agreement | anti-CD39 |  |  |  |  |  |  |
License And Collaboration Agreements [Line Items] |  |  |  |  |  |  |
Development milestone expense | 0 |  | $ 0 |  |  |  |
WuXi Biologics License Agreement | Maximum | anti-PD-1 |  |  |  |  |  |  |
License And Collaboration Agreements [Line Items] |  |  |  |  |  |  |
Clinical regulatory milestone payments | 50 |  |  |  |  |  |
Clinical, regulatory and commercialization milestone payments | 375 |  |  |  |  |  |
WuXi Biologics License Agreement | Maximum | anti-CD39 |  |  |  |  |  |  |
License And Collaboration Agreements [Line Items] |  |  |  |  |  |  |
Additional clinical, regulatory and commercialization milestone payments | $ 14 |  |  |  |  |  |

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