Short immunotherapy course before surgery keeps bowel cancer patients recurrence-free for nearly three years
In the NEOPRISM-CRC trial, nine weeks of pembrolizumab before surgery left all 32 patients with a specific bowel cancer recurrence-free after 33 months.
Summary
A small clinical trial suggests a brief course of immunotherapy before surgery may give lasting protection against one genetic form of bowel cancer. In the NEOPRISM-CRC trial, 32 patients with stage two or three disease received the drug pembrolizumab for up to nine weeks before surgery, instead of the usual chemotherapy afterward. After 33 months of follow-up, none had a recurrence. That included patients who still had small traces of disease after treatment, and those traces did not grow or spread. Earlier results showed 59% had no detectable disease after treatment and surgery. By comparison, about 25% of patients on the standard surgery-plus-chemotherapy path are expected to relapse within three years. Researchers also developed personalized blood tests to show early whether treatment worked, which could help doctors give less treatment to some patients and more to others. The trial is small and has no control group, so larger studies are needed. Even so, the results point toward more precise, less burdensome cancer care.
Detailed Summary
Bowel cancer mostly affects older adults, though rates in people under 50 have been climbing. Standard care for stage two or three disease is surgery followed by chemotherapy, yet roughly one in four patients still relapse within three years. Chemotherapy also carries real costs to health and function. A treatment that prevents recurrence with less exposure would matter for long-term healthspan after cancer.
The NEOPRISM-CRC trial, led by researchers at UCL and UCLH, tested a different sequence. Thirty-two patients with a specific genetic form of bowel cancer received the immunotherapy drug pembrolizumab for up to nine weeks before surgery, instead of post-surgery chemotherapy. Earlier results showed major tumor shrinkage, and 59% of patients had no detectable disease after treatment and planned surgery.
The new follow-up, due at the AACR Annual Meeting 2026, reports that after 33 months none of the patients had a recurrence. This held for patients with no disease remaining and for those with small residual traces, which did not grow or spread. Against an expected relapse rate of about 25% with standard care, this is striking.
The team also analyzed blood samples to understand why the therapy worked. They built personalized blood tests that show early whether treatment has succeeded and whether cancer traces still circulate. Together with immune profiling, these tools might one day identify patients who need less therapy and those at higher risk who need more. Dr. Kai-Keen Shiu called the results extremely encouraging.
There are important caveats. The trial is small, with only 32 patients, and has no randomized comparison group, so the comparison with standard care relies on expected rates. The benefit applies to a specific genetic subtype of bowel cancer, not all cases. Follow-up of under three years cannot confirm lasting cure, and the blood tests still need validation. Patients should not expect this approach for other bowel cancers, and treatment decisions belong with an oncology team. Larger trials will show whether the early promise holds.
Key Findings
- None of 32 patients had a cancer recurrence after 33 months of follow-up following pre-surgery pembrolizumab.
- Earlier data showed 59% of patients had no detectable disease after nine weeks of treatment and surgery.
- Patients with residual traces of disease also stayed recurrence-free, and the remaining cancer did not grow or spread.
- Standard surgery plus chemotherapy is expected to leave about 25% of patients relapsing within three years.
- Personalized blood tests and immune profiling may predict response and guide how much treatment each patient needs.
Methodology
This is a university news release summarizing results from the NEOPRISM-CRC clinical trial, to be presented at the AACR Annual Meeting 2026. The source, UCL, is credible, but the findings are not yet peer-reviewed in the article. The evidence is a small single-arm trial compared with expected historical relapse rates.
Study Limitations
The trial enrolled only 32 patients, had no randomized control arm, and followed them for under three years, so durability remains unproven. The article does not name the genetic subtype or detail side effects, and the blood tests are not yet validated. Check the full AACR presentation or publication for those details.
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