Agenus' Immunotherapy Combo Shows 33% Three-Year Survival in Refractory Colorectal Cancer — Agenus Inc.

Event summary

Agenus reported three-year Phase 1b data showing 33% overall survival in refractory MSS metastatic colorectal cancer without active liver metastases using botensilimab plus balstilimab.
Median overall survival was 21.2 months, with a plateau in the Kaplan-Meier curve beyond two years.
The study included 123 patients who had received a median of three prior lines of therapy.
No new safety signals were observed, and treatment-related immune-mediated diarrhea/colitis resolved in 98% of affected patients.

The big picture

Agenus' data challenges the historical limitations of immunotherapy in refractory microsatellite-stable (MSS) colorectal cancer, a subset with few durable treatment options. The results suggest potential for BOT+BAL to redefine expectations for long-term survival in heavily pretreated patients. This positions Agenus in a competitive immuno-oncology landscape where combination therapies are increasingly critical.

What we're watching

Clinical Validation: Whether the durable survival and treatment-free intervals observed can position BOT+BAL as a differentiated immunotherapy regimen in refractory MSS mCRC.
Regulatory Pathway: The pace at which Agenus advances the ongoing Phase 3 BATTMAN trial, given the mature efficacy and safety data from the Phase 1b study.
Market Differentiation: How Agenus will leverage these results to compete against existing later-line standards like regorafenib and trifluridine/tipiracil in the refractory MSS mCRC space.