TL;DR
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In the UK NEOPRISM-CRC trial, none of 32 patients with a specific genetic subtype of stage two or three bowel cancer had a recurrence during almost three years of follow-up after pembrolizumab before surgery. Researchers say the results extend earlier findings, but the small trial does not establish that the approach should replace standard care for all patients.
None of the 32 patients in a UK clinical trial of pembrolizumab before surgery for a specific form of stage two or three bowel cancer had a recurrence during 33 months of follow-up, researchers from UCL and UCLH reported. The result extends earlier evidence that a short course of immunotherapy can shrink these tumors, but the small trial does not show that the approach works for every bowel cancer type or should replace standard treatment.
The NEOPRISM-CRC trial enrolled patients whose tumors were mismatch repair deficient or microsatellite instability-high (MMR-deficient/MSI-high), a genetic profile found in an estimated 10% to 15% of people with stage two or three bowel cancer. Participants received up to nine weeks of pembrolizumab before their planned bowel surgery. The trial involved five UK hospitals.
Earlier trial results found that 59% of participants had no detectable disease after immunotherapy and surgery. In the latest follow-up, none of the participants had a reported cancer recurrence, including people who had small amounts of disease remaining after treatment. Researchers said that residual cancer did not grow or spread during the follow-up period.
The researchers also examined blood and tumor samples. They reported that the disappearance of tumor DNA from the bloodstream was strongly associated with no cancer being found after treatment. Immune profiling of tumor tissue collected before treatment may also help predict response, though these tests are being studied and are not established here as routine clinical decision tools.
What the Three-Year Follow-Up Shows
The findings matter because they suggest that, for patients with this specific genetic subtype, immunotherapy given before surgery may be followed by durable disease control. The source report says around 25% of patients receiving the usual approach of surgery followed by chemotherapy are expected to relapse within three years. That is a comparison with an expected outcome, not a randomized comparison within this trial, so it cannot establish that pembrolizumab caused a better result than standard treatment.
If further research supports the approach, it could change how some patients are treated and help clinicians identify who may need additional therapy. Personalized blood tests could potentially offer an earlier indication of response and help guide decisions. For now, the trial’s small size and selected patient group limit how broadly its results can be applied. The report does not establish that patients can safely forgo surgery or other treatment based on these findings.
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How NEOPRISM-CRC Treated Patients
The trial focused on stage two and three bowel cancers with MMR deficiency or MSI-high status. Rather than beginning with surgery and then giving three to six months of chemotherapy, participants were given pembrolizumab before their planned operation. The study was led by researchers at UCL and UCLH, with recruitment and sample contributions from hospitals in Southampton, Leeds and Manchester.
The new results build on earlier trial findings showing substantial tumor shrinkage after the short immunotherapy course. The latest analysis, described in an abstract for the American Association for Cancer Research annual meeting, adds longer follow-up and investigation of possible biological markers of response. The source report says the results are due to be presented at the meeting in April 2026; it does not provide a peer-reviewed full trial publication or a detailed account of the analysis methods.
“Seeing that no patients have experienced a cancer recurrence after almost three years of follow-up is extremely encouraging.”
— Dr. Kai-Keen Shiu, trial chief investigator at UCL and consultant medical oncologist at UCLH
Limits of the Trial Evidence
The reported result comes from 32 participants, all with a particular tumor profile, and the source material does not give a randomized control group or detailed patient-by-patient outcomes. It is not clear from the report whether all participants completed the full follow-up period, how recurrence was defined, or whether there were treatment-related harms that affected care. Those details matter when judging both the strength of the findings and the balance of benefits and risks.
The comparison with an expected relapse rate after standard care is not the same as a direct, controlled comparison. Researchers have not established from this report whether the blood tests can reliably guide treatment outside a research setting, or which patients might safely receive less additional therapy. The results should not be taken to mean that immunotherapy has made surgery or chemotherapy unnecessary for bowel cancer generally.
Further Follow-Up and Test Validation
The research team is continuing to monitor trial participants and study blood and tumor markers. The next evidence needed includes fuller reporting of the trial methods and outcomes, longer follow-up, and validation of the proposed personalized tests in larger groups. Those steps can help establish whether the findings hold beyond this small, selected cohort.
Researchers also need to determine how the treatment compares with standard care and how it should fit into clinical decisions for eligible patients. Until that evidence is available and guidance is updated, treatment choices remain matters for patients and their cancer teams, based on the individual’s diagnosis and clinical circumstances.
Key Questions
What did the bowel cancer trial report?
Researchers reported that none of 32 participants with MMR-deficient or MSI-high stage two or three bowel cancer had a recurrence during 33 months of follow-up after receiving pembrolizumab before surgery.
Does this mean immunotherapy cured the participants?
The report describes no recurrence during the follow-up period; it does not establish a cure. Longer monitoring is needed, and the trial was small and limited to a particular tumor subtype.
Was surgery still part of the treatment?
Yes. Participants received up to nine weeks of pembrolizumab before their planned bowel surgery. The findings do not show that surgery can be skipped.
Can a blood test show whether the treatment worked?
Researchers found that tumor DNA disappearing from the blood was strongly associated with no cancer remaining after treatment. The personalized tests are still under study; the report does not establish them as routine tests for treatment decisions.
Does the result apply to all bowel cancer patients?
No. The trial studied stage two or three bowel cancer with an MMR-deficient/MSI-high profile, which the report estimates affects 10% to 15% of patients at those stages. The findings cannot be assumed to apply to other bowel cancer types.
Source: rss
