A landmark clinical trial is challenging the standard treatment pathway for a subset of colorectal cancer patients, demonstrating that a short course of immunotherapy administered before surgery can eliminate recurrence entirely for nearly three years. The findings, presented at the American Association for Cancer Research (AACR) Annual Meeting 2026 in San Diego, mark one of the most encouraging outcomes yet in the push to simplify and improve colorectal cancer care.
The Trial: Key Results
Dr. Kai-Keen Shiu, Chief Investigator of the trial and a consultant medical oncologist at UCLH, called the results extremely encouraging. “Seeing that no patients have experienced a cancer recurrence after almost three years of follow-up strengthens our confidence that pembrolizumab is a safe and highly effective treatment to improve outcomes in patients with high-risk bowel cancers,” he said. “What is particularly exciting is that we now may be able to predict who will respond using personalized blood tests and immune profiling — tools that could help us tailor treatment, identifying patients who may need less therapy versus those at higher risk who need more.”
Professor Marnix Jansen of the UCL Cancer Institute offered additional perspective on the significance of the findings. “These results not only confirm the durability of responses we saw almost three years ago, but also provide crucial biological insights into why immunotherapy is so effective in this setting,” he said.
The findings carry important implications for how colorectal cancer is managed in a clinical context where diagnoses among younger adults have been rising steadily in recent years. Bowel cancer is the fourth most common cancer in the United Kingdom, with roughly 44,000 new cases diagnosed each year. Survival rates vary dramatically by stage: approximately 90% of patients with stage 1 disease survive at least five years, compared with 65% at stage 3 and just 10% at stage 4.
The trial’s results also arrive amid a broader shift in oncology toward de-escalating treatment — reducing the intensity and duration of therapy without sacrificing efficacy. For patients, the prospect of a nine-week immunotherapy “head start” instead of months of post-surgical chemotherapy represents a meaningful improvement in quality of life, with the potential for fewer side effects and faster recovery. Researchers acknowledged, however, that the approach is still investigational for this specific indication and will require validation in larger, randomized trials before becoming standard practice.
Why It Matters
The NEOPRISM-CRC trial was conducted across multiple UK hospitals, with UCL and UCLH serving as the primary research centers and Personalis, a biotechnology company, contributing analytical support. Funding came from the National Institute for Health and Care Research (NIHR), with pembrolizumab supplied by the manufacturer.
The full dataset was presented at AACR 2026 in San Diego. Study registration details and longer-term follow-up protocols are expected to be published in a peer-reviewed journal later this year.