License and Collaboration Agreement with ImmuneOnco	3 Months Ended
Mar. 31, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]
License and Collaboration Agreement with ImmuneOnco	License and Collaboration Agreement with ImmuneOnco On August 1, 2024, Axion Bio entered into a license and collaboration agreement (the “IO Collaboration Agreement”) with ImmuneOnco Biopharmaceuticals (Shanghai) Inc. (“ImmuneOnco”), under which it in-licensed several bispecific antibodies, including AXN-2510 and AXN-27M. As part of the IO Collaboration Agreement, Axion Bio made a $10.0 million upfront payment to ImmuneOnco during the year ended December 31, 2024. This amount was fully expensed as in-process research and development (IPR&D) in the same year. During the year ended December 31, 2024, Axion Bio made a $5.0 million prepayment to ImmuneOnco for development costs, which was fully recognized as research and development expense by March 31, 2025. In April 2025, Axion Bio made a second $5.0 million prepayment to ImmuneOnco for development costs, which was fully recognized as research and development expense by September 30, 2025. In August 2025, Axion Bio made a third $5.0 million prepayment to ImmuneOnco for development costs, which was fully recognized as research and development expense by the three months ended March 31, 2026. In June 2025, Axion Bio achieved Investigational New Drug (IND) clearance in the United States for a Phase 1 trial of AXN-2510 in relapsed/refractory solid tumors. This milestone triggered a $10.0 million development payment to ImmuneOnco, which was paid in July 2025. This amount was fully expensed as IPR&D during the second quarter of 2025. The expenses recognized in connection with the IO Collaboration Agreement were $0.3 million and $4.3 million for the three months ended March 31, 2026 and 2025, respectively, and were recorded as a component of research and development expense on the condensed consolidated statements of operations and comprehensive loss. As of March 31, 2026, no additional milestones were accrued. On January 5, 2026, Axion Bio and ImmuneOnco entered into an agreement terminating the IO Collaboration Agreement. Under the termination agreement, Axion Bio agreed to transfer the rights, title, and interest related to AXN-2510 and AXN-27M to ImmuneOnco, and ImmuneOnco agreed to pay Axion Bio $1.8 million, of which $1.6 million was received during the quarter ended March 31, 2026 and recorded as other income as a gain on contract termination in the condensed consolidated statements of operations and comprehensive loss. Receipt of the remaining $0.2 million is contingent upon the completion of specified wind-down activities.

On August 1, 2024, Axion Bio entered into a license and collaboration agreement (the “IO Collaboration Agreement”) with ImmuneOnco Biopharmaceuticals (Shanghai) Inc. (“ImmuneOnco”), under which it in-licensed several bispecific antibodies, including AXN-2510 and AXN-27M. As part of the IO Collaboration Agreement, Axion Bio made a $10.0 million upfront payment to ImmuneOnco during the year ended December 31, 2024. This amount was fully expensed as in-process research and development (IPR&D) in the same year.

During the year ended December 31, 2024, Axion Bio made a $5.0 million prepayment to ImmuneOnco for development costs, which was fully recognized as research and development expense by March 31, 2025. In April 2025, Axion Bio made a second $5.0 million prepayment to ImmuneOnco for development costs, which was fully recognized as research and development expense by September 30, 2025. In August 2025, Axion Bio made a third $5.0 million prepayment to ImmuneOnco for development costs, which was fully recognized as research and development expense by the three months ended March 31, 2026.

In June 2025, Axion Bio achieved Investigational New Drug (IND) clearance in the United States for a Phase 1 trial of AXN-2510 in relapsed/refractory solid tumors. This milestone triggered a $10.0 million development payment to ImmuneOnco, which was paid in July 2025. This amount was fully expensed as IPR&D during the second quarter of 2025.

The expenses recognized in connection with the IO Collaboration Agreement were $0.3 million and $4.3 million for the three months ended March 31, 2026 and 2025, respectively, and were recorded as a component of

research and development expense on the condensed consolidated statements of operations and comprehensive loss. As of March 31, 2026, no additional milestones were accrued.

On January 5, 2026, Axion Bio and ImmuneOnco entered into an agreement terminating the IO Collaboration Agreement. Under the termination agreement, Axion Bio agreed to transfer the rights, title, and interest related to AXN-2510 and AXN-27M to ImmuneOnco, and ImmuneOnco agreed to pay Axion Bio $1.8 million, of which $1.6 million was received during the quarter ended March 31, 2026 and recorded as other income as a gain on contract termination in the condensed consolidated statements of operations and comprehensive loss. Receipt of the remaining $0.2 million is contingent upon the completion of specified wind-down activities.