Pre-surgery pembrolizumab stops recurrence in high-risk bowel cancer patients for three years
A nine-week neoadjuvant pembrolizumab regimen prevented any cancer recurrence over nearly three years in 32 stage II/III bowel-cancer patients, even those with residual disease.
Researchers at University College London and UCLH conducted the NEOPRISM-CRC study, giving a short course of the checkpoint inhibitor pembrolizumab to 32 patients with stage II or III MMR-deficient/MSI-high bowel cancer before their planned surgeries. This pre-operative approach replaced the standard regimen of surgery followed by three to six months of chemotherapy. After a median follow-up of 33 months, none of the patients showed any cancer recurrence, a result that held true even for those with tiny amounts of residual disease.
Analyses of blood samples revealed that loss of circulating tumor DNA matched complete pathological response, and immune profiling of initial tumor tissue may help identify likely responders. The data, presented at the AACR 2026 meeting, suggest that brief neoadjuvant immunotherapy could provide more durable control and reduce the need for extensive chemotherapy in this genetic subgroup, which accounts for roughly 10-15 % of UK stage II/III cases.
Why it matters
The trial shows a potentially safer, more effective pre-surgery treatment that could change standard care for a common genetic type of bowel cancer.
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