Agenus Secures $340M to Advance ROBBIN Trial of Botensilimab + Balstilimab in High‑Risk MSS Colon Cancer

Agenus is advancing its registrational Phase 3 ROBBIN trial evaluating the investigational combination of botensilimab and balstilimab as neoadjuvant treatment for high-risk Stage II and Stage III microsatellite-stable (MSS) colon cancer after securing up to $340 million through a private placement. The financing supports completion of the global study, which could establish the first new curative-intent treatment approach for this patient population in more than two decades.

MSS Colon Cancer Remains a Major Unmet Clinical Need

Microsatellite-stable colorectal cancer accounts for the majority of colorectal cancer cases but has remained largely resistant to conventional immune checkpoint inhibitors. Patients with high-risk Stage II and Stage III disease continue to rely on surgery with perioperative chemotherapy, while no new therapies with curative intent have been approved for this setting in more than 20 years. Agenus estimates that approximately 38,000 patients in the United States and more than 200,000 worldwide are diagnosed with high-risk MSS colon cancer annually.

Botensilimab is an investigational multifunctional CTLA-4 antibody developed to enhance anti-tumor immune responses, while balstilimab is an investigational PD-1 inhibitor. The combination is administered before surgery to stimulate a broader immune response while the primary tumor remains intact, potentially reducing recurrence risk and improving long-term outcomes.

Phase 2 NEST and UNICORN Studies Support Phase 3 Development

The Phase 3 ROBBIN study builds on encouraging results from the Phase 2 NEST (NCT05571293) and UNICORN trials (NCT05845450), where neoadjuvant botensilimab plus balstilimab produced pathologic responses in approximately 60% to 70% of patients, major pathologic responses in 35% to 40%, and pathologic complete responses in around 30%. With a median follow-up ranging from approximately 9 to 18 months, all treated patients remained disease free. The studies also demonstrated circulating tumor DNA (ctDNA) clearance during treatment, further supporting the combination’s advancement into registrational testing.

ROBBIN Phase 3 Trial to Evaluate Neoadjuvant BOT+BAL

ROBBIN is a randomized global Phase 3 trial that will enroll approximately 850 previously untreated patients with high-risk Stage II and Stage III MSS colon cancer. Participants will be randomized 1:1 to receive neoadjuvant botensilimab plus balstilimab followed by standard of care or standard of care alone. The study’s primary endpoint is event-free survival (EFS). Agenus said it has aligned with the U.S. Food and Drug Administration on key aspects of the study, including the patient population, treatment regimen, control arm, primary endpoint, and interim analysis plan.

Chief Medical Officer Steven O’Day, M.D., said the combination has shown deep pathologic responses in a tumor type historically resistant to checkpoint inhibition. He noted that administering immunotherapy before surgery may provide the greatest opportunity to generate durable anti-tumor immunity and improve long-term patient outcomes.

Founder and CEO Garo H. Armen, Ph.D., added that prioritizing the neoadjuvant program reflects the strength of the emerging clinical evidence and the potential to improve cure rates in earlier-stage MSS colon cancer.

Agenus Secures Up to $340 Million to Advance ROBBIN Program

To support this clinical strategy, Agenus entered into a private placement expected to provide approximately $85 million in upfront gross proceeds, with the potential to receive an additional $255 million through the exercise of purchase warrants, bringing the total financing to up to $340 million. Led by Commodore Capital with participation from RA Capital Management, TCGX, Invus, and Ligand Pharmaceuticals, the financing is expected to fund completion of the ROBBIN program and extend the company’s operational runway through year-end 2031, assuming full warrant exercise. The transaction is expected to close on or about July 15, 2026, subject to customary closing conditions.

As part of its strategic reprioritization, Agenus will discontinue financial support for the ongoing BATTMAN Phase 3 study evaluating botensilimab plus balstilimab in late-line metastatic MSS colorectal cancer. The company said it will continue to meet its obligations to patients currently receiving treatment while working with investigators and the Canadian Cancer Trials Group to manage the transition responsibly.

Looking ahead, Agenus expects to dose the first patient in the ROBBIN trial during the first quarter of 2027. Interim pathologic response data are anticipated in the second half of 2027, followed by an interim event-free survival analysis in the second half of 2029 and the final EFS analysis in the second half of 2030. If successful, the trial could expand the role of immunotherapy into earlier-stage MSS colon cancer, an area where treatment options have remained largely unchanged for decades.

Reference

Agenus Inc. – Agenus Announces Oversubscribed Private Placement of Up to $340 Million to Advance Registrational ROBBIN Trial of Neoadjuvant BOT+BAL in MSS Colon Cancer