Zero Relapse Rate Reported in UCL Trial Using Pre-Operative Immunotherapy for High-Risk Bowel Cancer

UCL trial shows 100% cancer-free rate for bowel cancer patients after three years using pre-op immunotherapy. A major breakthrough in MMR-deficient cancer care.

By: AXL Media

Published: Apr 21, 2026, 4:47 AM EDT

Source: Information for this report was sourced from University College London (UCL)

A Paradigm Shift in Neoadjuvant Oncology

A revolutionary approach to treating stage two and three bowel cancer is yielding unprecedented results in a clinical setting. Findings from the NEOPRISM-CRC trial, presented at the American Association for Cancer Research (AACR) Annual Meeting 2026, reveal that patients treated with immunotherapy prior to surgery have remained entirely cancer-free for nearly three years. This neoadjuvant—or pre-operative—strategy represents a major departure from the traditional standard of care, which involves primary surgery followed by three to six months of systemic chemotherapy. By shifting the timing of the intervention, clinicians have successfully triggered "major tumor shrinkage" and sustained remission in a patient group previously vulnerable to early relapse.

Targeting the MMR-Deficient Genetic Profile

The study specifically focused on a subset of bowel cancer characterized by a "mismatch repair deficient" (dMMR) or "microsatellite instability-high" (MSI-high) genetic profile. This particular makeup, found in approximately 10 to 15 percent of stage two and three cases, is often less responsive to traditional chemotherapy. The trial recruited 32 patients from across the UK, providing them with up to nine weeks of pembrolizumab. For patients like 73-year-old Christopher Burston, the results were transformative; his stage three tumor was described as having "melted away" prior to his surgical procedure in May 2023, leaving him cancer-free and active years later.

The Role of Personalized Liquid Biopsies

Beyond the survival data, the UCL and UCLH team utilized cutting-edge translational research to monitor the efficacy of the treatment in real-time. In collaboration with the biotechnology firm Personalis, researchers developed personalized blood tests—often referred to as liquid biopsies—to track circulating tumor DNA (ctDNA). These tests showed that when tumor DNA disappeared from the bloodstream early in the treatment cycle, it accurately predicted a complete pathological response. This ability to "see" the cancer’s disappearance before surgery offers a new level of precision in determining which patients require aggressive follow-up and which may eventually be spared more toxic therapies.