Zero Relapses in Landmark Bowel Cancer Immunotherapy Trial

A groundbreaking trial shows that a short course of immunotherapy before surgery eliminated cancer relapses in bowel cancer patients for nearly three years.

The NEOPRISM-CRC trial, presented at the American Association for Cancer Research Annual Meeting 2026, involved 32 patients with stage two or three MMR-deficient bowel cancer from five UK hospitals.

Patients received up to nine weeks of pembrolizumab before surgery, instead of standard post-operative chemotherapy. Initial results showed 59% had no detectable cancer after treatment. New data reveal zero relapses after 33 months of follow-up.

Dr Kai-Keen Shiu, chief investigator from UCL Cancer Institute, said the results strengthen the case for pembrolizumab as a safe, highly effective treatment for high-risk bowel cancer. Typically, 25% of patients receiving standard therapy relapse within three years.