• A novel, chemo-sparing strategy (BBoPCO): introducing BOT+BAL in 1L MSS mCRC to extend survival and reduce use of cytotoxic chemotherapy

Agenus Inc. (Nasdaq: AGEN), a leader in immuno-oncology, today announced that preliminary results from an investigator-sponsored study evaluating botensilimab (BOT) in combination with balstilimab (BAL) in first-line microsatellite stable colorectal cancer (MSS CRC) will be presented at the American Association for Cancer Research (AACR) Annual Meeting 2026, taking place April 18–23 in San Diego, CA.

The BBoPCO study (Botensilimab and Balstilimab Optimization in Colorectal Cancer; NCT06268015) is the first trial of its kind to advance a combination immunotherapy approach in the first-line setting for MSS mCRC, evaluating BOT+BAL in patients without liver, bone, or brain metastases—a population historically resistant to immunotherapy. This investigator-sponsored study was expanded to a Phase 2 and reflects a growing shift toward introducing immunotherapy earlier in the disease course, with the goal of harnessing the immune system to reduce reliance on chemotherapy and improve durability of response.

Colorectal cancer remains a leading cause of cancer-related death worldwide, with rising incidence in younger populations, and treatment continues to rely heavily on intensive, toxic chemotherapy regimens that can significantly impact quality of life, with neuropathy, organ toxicity, decrease fertility, among others. Despite advances, patients with MSS mCRC, which accounts for approximately 95% of metastatic cases, have seen limited benefit from conventional immunotherapy, underscoring a critical unmet need.

Botensilimab, an Fc-enhanced multifunctional anti-CTLA-4 antibody, is designed to activate both innate and adaptive immune responses, while balstilimab (anti–PD-1) is designed to sustain immune activity. Together, the combination is intended to target complementary immune pathways and expand the potential of immunotherapy in traditionally “cold” tumors.

The BBOpCo study adds to a growing body of research evaluating BOT+BAL across earlier lines of therapy and in settings where immune activation may have greater impact.

Presentation Details:

Poster Presentation Title: Preliminary results of first-line botensilimab (BOT) and balstilimab (BAL) optimization in microsatellite stable colorectal cancer (MSS CRC) without liver, bone, or brain metastasis (BBOpCo)

Presenting Author: Nicholas C. DeVito MD, Duke University, Assistant Professor of Medicine, Duke University, Division of Medical Oncology
Abstract No.: CT184
Session Title: Phase I Clinical Trials
Session Date: Tuesday, April 21, 2026
Session Time: 9:00AM – 12:00 PM PT / 12:00-3:00 PM ET
Location: Poster Section 50
Board No: 6

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 1,200 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 2024, 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.

Source: Agenus Bio

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