TLDRBOT+BAL delivers 21.2-month median survival in refractory MSS colorectal cancer.Three-year overall survival reaches 33% in Agenus’ fully enrolled Phase 1b cohort.Confirmed response rate hits 21%, including three complete and 23 partial responses.BOT+BAL responses appear even in tumors with low TMB and no detectable PD-L1.Extended follow-up finds no new safety signals and no treatment-related deaths.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%.Agenus Inc., AGENC-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.BOT+BAL Shows Durable Survival in Refractory MSS Colorectal CancerAgenus 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%.Heavily Pretreated Patients Maintain Clinical BenefitThe 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.Biomarker Results and Safety Support Further BOT+BAL DevelopmentExploratory 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.