On October 17, 2025 Agenus Inc. (Nasdaq: AGEN), a leader in immuno-oncology innovation, reported 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) (Free ESMO Whitepaper) 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.
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"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."
Broader Presence at ESMO (Free ESMO Whitepaper) 2025
In addition to the pan-tumor dataset, three additional posters will be presented highlighting clinical activity across hard-to-treat cancers:
Cervical cancer: Results from the global Phase 2 RaPiDs trial (Abstract #2952)
MSS mCRC: A Phase 1 trial of BOT/BAL + regorafenib (Abstract #6197)
Non-melanoma skin cancer: Data from the AGENONMELA study (Abstract #7273)
These presentations further support the breadth and versatility of Agenus’ immunotherapy pipeline across diverse cancer types and clinical settings.
(Press release, Agenus, OCT 17, 2025, View Source [SID1234656742])