A phase 1 clinical trial tested the combination of the immunotherapy drugs botensilimab and balstilimab in patients with the most common form of colorectal cancer, also known as colon cancer.[1] These monoclonal antibodies activate the body's immune system to attack the cancer.[1] Of the 101 patients who completed the six-month follow-up, 61% had tumor shrinkage or a stable condition after treatment.[1] These are the first reported consistent and durable responses to immunotherapy in patients with difficult-to-treat forms, including MSS colorectal cancer.[1] The most common side effects were diarrhea and fatigue.[1] The study was published in Nature Medicine and provides evidence for the effectiveness of immunotherapy in all forms of colorectal tumors.[1]