Agenus Inc. (AGEN) shares traded at $7.67, down 1.79%, as newly published BOT+BAL colorectal cancer data drew attention. The company reported mature Phase 1b results from 123 heavily pretreated patients with microsatellite-stable metastatic colorectal cancer. The study showed median overall survival of 21.2 months and a three-year overall survival rate of 33%.
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C-800-01 enrolled patients receiving BOT at 1 mg/kg or 2 mg/kg every six weeks alongside BAL. BAL was administered at 3 mg/kg every two weeks, while safety and tolerability served as the primary endpoint. Secondary endpoints included response, response duration, disease control, and progression-free survival, while overall survival remained exploratory.
Agenus tested botensilimab with balstilimab in patients without active liver metastases and limited remaining treatment options. Participants had received a median of three prior treatment lines before entering the fully enrolled C-800-01 cohort. Clinical Cancer Research published the findings after three-year efficacy data were presented at the ESMO GI Congress 2026.
MSS tumors represent most metastatic colorectal cancer cases and usually respond poorly to conventional checkpoint immunotherapy. Available later-line treatments have reported median overall survival near 10 to 14 months in comparable refractory patients. Against that historical range, BOT+BAL produced median overall survival of 21.2 months across the Phase 1b cohort.
The confirmed objective response rate reached 21%, including three complete responses and 23 partial responses. Median response duration was not reached, while reported responses continued for at least 37.4 months during follow-up. Disease control reached 69% at six weeks, while the 24-week clinical benefit rate stood at 28%.
The study also examined 37 patients who had already exhausted available later-line therapies before receiving BOT+BAL. These patients had received a median of five earlier treatment lines, reflecting a particularly refractory disease setting. Even there, the confirmed objective response rate reached 22%, while median overall survival reached 16.2 months.
The subgroup posted a three-year overall survival rate of 30%, showing continued activity after several earlier treatments. Median response duration reached 16.6 months, while disease control reached 70% during the exploratory subgroup analysis. The clinical benefit rate reached 27% at 24 weeks, indicating preserved activity despite extensive prior therapy.
Across the broader cohort, 17% of patients remained alive without any systemic anticancer therapy at last follow-up. That treatment-free group included 13 responders, showing that several patients maintained clinical benefit after study treatment ended. Patients received a median of only two BOT doses and six BAL doses, despite the durable activity reported.
Exploratory biomarker work showed responses in tumors with low tumor mutational burden and no detectable PD-L1 expression. Neither biomarker showed an association with response across the evaluable population included in the publication. Therefore, BOT+BAL activity was not confined to tumors carrying conventional biological markers linked with checkpoint sensitivity.
Agenus designed botensilimab as an Fc-enhanced anti-CTLA-4 antibody supporting both innate and adaptive immune responses. Its mechanism aims to activate Fc-gamma receptors, promote T-cell priming, reduce regulatory T cells, and reshape the tumor environment. Balstilimab blocks PD-1 interactions, while the combined evidence supports planned Phase 3 ROBBIN testing alongside neoadjuvant NEST data.
Extended follow-up identified no new safety signals, and researchers reported no treatment-related deaths across the cohort. Immune-mediated diarrhea or colitis resolved in 98% of affected patients, with median resolution taking 14 days. Both BOT dose levels produced 21% response rates, while the 1 mg/kg regimen showed fewer immune-mediated adverse events.
The post Agenus Inc. (AGEN) Stock: BOT+BAL Delivers 21.2-Month Survival in Colorectal Cancer Trial appeared first on Blockonomi.
