Agenus Releases New Data From Its botensilimab And balstilimab Combination Showing Durable Survival Benefits Across Multiple Late-Stage, Treatment-Resistant Cancers And That ~40% Of Patients With Very Limited Survival Expectation Are Alive At Two Years

Author: Benzinga Newsdesk | October 17, 2025 08:10am

• Durable survival in heavily pretreated patients, including those who failed prior immunotherapy and with active liver metastases
• Signals of tumor agnostic benefit observed
• Tumor types included CRC, sarcoma, ovarian, NSCLC, and liver

Agenus Inc. (NASDAQ:AGEN), a leader in immuno-oncology innovation, today announced new data from its botensilimab (BOT), a multifunctional, Fc-enhanced CTLA-4 antibody and balstilimab (BAL), a PD-1 inhibitor, combination demonstrating durable survival across multiple cancer types in late-stage patients who have limited treatment options. The results, featured in an oral session at the European Society for Medical Oncology (ESMO) Congress 2025 in Berlin, Germany presented by Dr. Michael Gordon of HonorHealth Research Institute, include emerging two-year survival plateaus indicating a strong clinical signal that BOT/BAL's benefit may be agnostic to tumor type.

"With longer follow up, we're finding that approximately 40% of patients with very limited survival expectation are alive at two years," said Michael S. Gordon, MD, HonorHealth Research Institute. "These results are in patients with cancers that historically have been resistant to earlier immunotherapy approaches or have progressed following prior immunotherapy treatment, and they support advancing randomized trials like the phase 3 BATTMAN trial to create an immunotherapy option for patients who have historically had none."

Highlights from the Oral Presentation (Abstract #1517MO):

New data from expansion cohorts of 411 patients (339 evaluable for efficacy) enrolled in the Phase 1b C-800-01 study evaluating BOT/BAL in patients with advanced, refractory disease across more than 5 cancer types.

• 61% of patients enrolled received three or more prior lines of therapy
• Objective response rates (ORR): 17% across both BOT 1 mg/kg and 2 mg/kg doses
• Signals of benefit across tumor types, including those historically unresponsive to immunotherapy, had prior treatment with checkpoint inhibitors, and/or with active liver metastases.
• 2-year median overall survival (OS): 39%
• Median OS (mOS): 17.2 months
• Combination was well tolerated with most immune‑related side effects were reversible and gastrointestinal in nature; no treatment‑related deaths occurred
• Immune activation correlated with improved survival

These findings build on previously reported 2-year overall survival of 42% and median OS of 20.9 months with BOT/BAL in refractory MSS mCRC with non-liver metastasesi and complement emerging data in the neoadjuvant setting, where BOT/BAL has also shown activity across multiple tumor typesii, further underscoring the platform potential of Agenus' next-generation Fc-enhanced CTLA-4.

In a further validation of its clinical impact, the French National Authority for Health (HAS) recently authorized BOT in combination with BAL under France's Compassionate Access(AAC) early access program. This marks the first government-funded access pathway in France, for patients with refractory microsatellite‑stable (MSS) metastatic colorectal cancer (mCRC) who have exhausted all available treatment options.

"BOT/BAL's immune activation profile is truly differentiated," said Steven J. O'Day, MD, Chief Medical Officer, Agenus. "We are seeing consistent signals that this combination can convert ‘cold,' IO‑resistant tumors into responsive ones, not only in late-line settings but potentially in earlier lines where immunotherapy may deliver even greater benefit."

Posted In: AGEN