Agenus Reports Landmark BOT+BAL Data Showing 33% Three-Year Overall Survival in Refractory MSS Metastatic Colorectal Cancer Without Active Liver Metastases at ESMO GI 2026

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Treatment-related immune-mediated diarrhea/colitis was the most common immune-mediated adverse event (42%; grade ≥3, 15%). The selected Phase 3 regimen of BOT 1 mg/kg plus BAL demonstrated improved tolerability, with lower rates of immune-mediated diarrhea/colitis (27%; grade ≥3, 10%) than the 2 mg/kg regimen.

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Together, the mature efficacy, treatment-free survival, and extended safety findings support continued evaluation of BOT+BAL in MSS mCRC and provide rationale for the ongoing randomized Phase 3 BATTMAN trial evaluating BOT+BAL in refractory MSS/proficient mismatch repair (pMMR) metastatic colorectal cancer.

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Presentation Details

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Abstract Title:

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Botensilimab + Balstilimab in Microsatellite-Stable Metastatic Colorectal Cancer Without Active Liver Metastases: Extended Follow-Up and 3-Year Survival

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Presenter:

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Benjamin L. Schlechter, M.D.; Dana-Farber Cancer Institute, Boston, MA, USA

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Final Publication Number:

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91P

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Congress:

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European Society for Medical Oncology Gastrointestinal Cancers Congress 2026

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Location:

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ESMO GI, 2026 | Munich, Germany

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Poster Availability:

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The poster is available on the Agenus publications

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About the C-800-01 Study (NCT03860272)

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C-800-01 is a first-in-human Phase 1b clinical trial evaluating botensilimab with or without balstilimab in patients with advanced solid tumors. The MSS mCRC without active liver metastases cohort enrolled 123 patients who received BOT 1 mg/kg or 2 mg/kg every six weeks plus BAL 3 mg/kg every two weeks. The primary endpoint was safety and tolerability. Secondary endpoints included objective response rate, duration of response, disease control rate, and progression-free survival. Exploratory endpoints included overall survival and clinical benefit rate.

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About Agenus

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Agenus is a leading immuno-oncology company targeting cancer with a comprehensive pipeline of immunological agents. The company was founded in 1994 with a mission to expand patient populations benefiting from cancer immunotherapy through combination approaches, using a broad repertoire of antibody therapeutics, adoptive cell therapies (through MiNK Therapeutics) and adjuvants. Agenus has robust end-to-end development capabilities, across commercial and clinical cGMP manufacturing facilities, research and discovery, and a global clinical operations footprint. Agenus is headquartered in Lexington, MA. For more information, visit www.agenusbio.com or @agenus_bio. Information that may be important to investors will be routinely posted on our website and social media channels.

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About Botensilimab (BOT)

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Botensilimab (BOT) is a human Fc enhanced multifunctional anti-CTLA-4 antibody designed to boost both innate and adaptive anti-tumor immune responses. Its novel design leverages mechanisms of action to extend immunotherapy benefits to “cold” tumors which generally respond poorly to standard of care or are refractory to conventional PD-1/CTLA-4 therapies and investigational therapies. Botensilimab augments immune responses across a wide range of tumor types by priming and activating T cells, downregulating intratumoral regulatory T cells, activating myeloid cells and inducing long-term memory responses.

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Approximately 1,300 patients have been treated with botensilimab and/or balstilimab in phase 1 and phase 2 clinical trials. Botensilimab alone, or in combination with Agenus’ investigational PD-1 antibody, balstilimab, has shown clinical responses across nine metastatic, late-line cancers. For more information about botensilimab trials, visit www.clinicaltrials.gov.

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About Balstilimab (BAL)

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Balstilimab is a novel, fully human monoclonal immunoglobulin G4 (IgG4) designed to block PD-1 (programmed cell death protein 1) from interacting with its ligands PD-L1 and PD-L2. It has been evaluated in more than 900 patients to date and has demonstrated clinical activity and a favorable tolerability profile in several tumor types.

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Forward-Looking Statements

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This press release contains forward-looking statements that are made pursuant to the safe harbor provisions of the federal securities laws, including statements regarding its botensilimab and balstilimab programs, expected regulatory timelines and filings, and any other statements containing the words “may,” “believes,” “expects,” “anticipates,” “hopes,” “intends,” “plans,” “forecasts,” “estimates,” “will,” “establish,” “potential,” “superiority,” “best in class,” and similar expressions are intended to identify forward-looking statements. These forward-looking statements are subject to risks and uncertainties that could cause actual results to differ materially. These risks and uncertainties include, among others, the factors described under the Risk Factors section of our most recent Annual Report on Form 10-K for 2025, and subsequent Quarterly Reports on Form 10-Q filed with the Securities and Exchange Commission. Agenus cautions investors not to place considerable reliance on the forward-looking statements contained in this release. These statements speak only as of the date of this press release, and Agenus undertakes no obligation to update or revise the statements, other than to the extent required by law. All forward-looking statements are expressly qualified in their entirety by this cautionary statement.

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Contacts

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Investors

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917-362-1370 |

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Media

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781-674-4422 |

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