Pre-Surgery Immunotherapy Keeps Bowel Cancer From Returning in Small Trial
In the NEOPRISM-CRC trial, 32 patients with a specific genetic form of stage two or three bowel cancer received pembrolizumab for up to nine weeks before surgery instead of standard post-surgery chemotherapy. After 33 months, none had a recurrence, including patients with small traces of disease remaining after treatment. The results extend earlier findings of major tumor shrinkage and are due to be presented at AACR 2026.
The NEOPRISM-CRC study enrolled 32 people whose stage two or three bowel cancer had a particular genetic profile. They received pembrolizumab for no more than nine weeks before their planned operation, rather than chemotherapy afterward. Earlier trial data showed 59% had no detectable disease following immunotherapy and surgery.
After 33 months, no participant's cancer had returned, even among those with residual traces that neither grew nor spread. For comparison, about a quarter of patients given standard surgery plus chemotherapy typically relapse within three years. Bowel cancer is the UK's fourth most common cancer, with around 44,000 diagnoses annually; younger adult cases have increased recently.
If confirmed, this approach could change treatment sequencing for eligible bowel cancer patients, potentially sparing some from post-surgery chemotherapy and its burdens. It may also encourage wider use of blood-based monitoring and immune profiling to tailor care. Because the trial is small and the findings are due to be presented at a conference, broader access and cost implications remain uncertain; benefits may initially reach only those treated at research centers.