Phase 2 botensilimab Fc‑enhanced anti‑CTLA‑4 + balstilimab PD‑1 antibody in MSS colon cancer

City of Hope Medical Center is running this Phase 2 neoadjuvant study (NEST3) testing whether short-course dual checkpoint blockade—botensilimab (a next‑generation, Fc‑enhanced anti‑CTLA‑4 monoclonal antibody) plus balstilimab (an anti‑PD‑1 monoclonal antibody)—can induce meaningful pathologic tumor regression before standard colon resection in resectable stage IIB–IIIC, first-line MSS/pMMR colon cancer. Treatment is botensilimab IV on day 1 plus balstilimab IV on days 1, 15, 29, and 43, followed by surgery 5–16 weeks later, with imaging (CT/MRI) and blood/biospecimen collection to correlate immune effects with response. The scientific/commercial angle is bringing an immunotherapy backbone that has shown signals in “cold” MSS colorectal cancer into the curative-intent window, where even modest increases in deep response could translate into fewer recurrences. Today’s care for resectable stage II–III colon cancer is upfront surgery followed by risk-adapted adjuvant chemotherapy (commonly fluoropyrimidine + oxaliplatin), while immunotherapy is largely reserved for dMMR/MSI‑H disease rather than MSS/pMMR.