Researchers report first effective use of immunotherapy for most common subtype of colorectal cancer

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Study Title: Botensilimab plus balstilimab in relapsed/refractory microsatellite stable metastatic colorectal cancer: a phase 1 trial

Publication: Nature Medicine, June 13, 2024

Dana-Farber Cancer Institute author: Benjamin L. Schlechter, MD, co-first author


Despite significant advances in immunotherapy for various cancers, immune based treatments for microsatellite stable (MSS) colorectal cancer, the most common subtype, have remained ineffective. In this study, researchers report the first safe and effective use of immunotherapy for MSS colorectal cancer that is resistant to chemotherapy. In a phase I clinical trial, 73% of patients whose cancer benefited from the combination therapy of immune checkpoint inhibitors botensilimab and balstilimab, but the benefit was limited to patients without active liver metastases. Nearly a quarter of patients had a major response to treatment. 


These clinical trial results point to the first safe and effective use of immunotherapy for patients with MSS colorectal cancer, the most common subtype of the disease. The encouraging results of this phase I trial have prompted investigators to move forward with a phase III trial of this immunotherapy combination. Schlechter and Dana-Farber investigators will have a leading role in the upcoming phase III trial.


The trial was supported with funding from Agenus, Inc.

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A colorectal cancer cell. Credit: Getty Images.