Phase 2 Study of Botensilimab and Balstilimab as Additional Treatment for Colorectal Cancer or Liver Metastases with Residual Tumor DNA After Surgery and Chemotherapy

What this Trial Is About

Researchers are evaluating whether the combination of botensilimab and balstilimab BOTBAL, followed by balstilimab alone, can be an effective treatment for people with microsatellite stable MSS colorectal cancer or colorectal liver metastases CRLM who have measurable residual disease MRD after standard surgery and chemotherapy or total neoadjuvant therapy TNT. This phase II study includes patients with persistent circulating tumor DNA ctDNA after treatment, aiming to understand treatment impact on disease recurrence. The study has two parts, each with two cohorts. Part 1 is a non-randomized study of 54 subjects assessing ctDNA clearance in patients with stage III non-MSI-HpMMR colorectal cancer or MSS CRLM after surgery and chemotherapy. Part 2 is a randomized, placebo-controlled, double-blind study of 230 patients assessing recurrence-free survival RFS. All patients receive botensilimab intravenously on day 1 of a 42-day cycle for 4 doses, and balstilimab intravenously on days 1, 15, and 29 of the same cycle. After these cycles, balstilimab alone continues for two more cycles on the same schedule. In Part 2, some patients may receive a placebo instead of balstilimab alone during the later cycles. Participants will be monitored through blood tests for ctDNA clearance and recurrence-free survival over 6 months to 1 year, depending on their cohort. The study includes assessments of disease status and safety monitoring during treatment cycles. Patients must consent to tissue and blood sample use for research and undergo genetic testing if not previously done. The total duration of participation varies by cohort and study part, with close follow-up for treatment effects and disease recurrence.

A Study of Botensilimab and Balstilimab for Colorectal Cancer With ctDNA+ After Surgery and Chemotherapy