Data reflect an additional year of follow-up from the 123-patient cohort in the Phase 1b study

Agenus Inc. (NASDAQ:AGEN), a leader in immuno-oncology innovation, today announced that three-year survival data from the Phase 1b C-800-01 study of botensilimab (BOT), an Fc-enhanced multifunctional anti–CTLA-4 antibody, plus balstilimab (BAL), an anti–PD-1 antibody, in patients with microsatellite stable (MSS) metastatic colorectal cancer (mCRC) without active liver metastases will be presented at the European Society for Medical Oncology Gastrointestinal Cancers Congress 2026, taking place July 1–4, 2026, in Munich, Germany.

The poster presentation, delivered by Benjamin L. Schlechter, M.D., of Dana-Farber Cancer Institute, will provide updated findings from the fully enrolled cohort of 123 patients, including longer-term follow-up of durability of response and overall survival. The presentation follows the two-year overall survival data presented by Dr. Schlechter at ESMO-GI 2025 and reflects an additional year of follow-up from the Phase 1b study.

Presentation Details:

Abstract Title: Botensilimab + Balstilimab (BOT+BAL) in Microsatellite-Stable Metastatic Colorectal Cancer Without Active Liver Metastases: Extended Follow-Up and 3-Year Survival

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

Final publication number: 91P

Session Title: Poster Display Session

Location: Foyer

Date/Time: 2 July 2026 | 15:30 –16:30 CEST, 9:30-10:30AM EST

About Agenus

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.

About Botensilimab (BOT)

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.

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.

About Balstilimab (BAL)

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.

Forward-Looking Statements

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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Agenus Announces Three-Year Survival Data from Phase 1b BOT+BAL Study in MSS Metastatic Colorectal Cancer to be Presented at ESMO GI 2026