A groundbreaking clinical trial, NEOPRISM-CRC, led by researchers at University College London (UCL) and University College London Hospitals (UCLH), has demonstrated remarkable efficacy of pre-surgical immunotherapy in patients with stage II or III MMR-deficient/MSI-high colorectal cancer. This genetic subtype, accounting for 10-15% of non-metastatic cases (approximately 2,000-3,000 annually in the UK, with similar prevalence in India where colorectal cancer incidence is rising), responds poorly to traditional therapies. In the study, 32 participants received a nine-week course of pembrolizumab, a PD-1 inhibitor, prior to surgery, bypassing the conventional approach of surgery followed by adjuvant chemotherapy. Initial results revealed that 59% of patients achieved pathological complete response, with no detectable cancer post-treatment. Strikingly, after a median follow-up of 33 months, none experienced recurrence, including those with residual microscopic disease that remained stable without progression. This contrasts sharply with standard care, where about 25% of similar patients relapse within three years. The findings, presented at the American Association for Cancer Research (AACR) Annual Meeting 2026, underscore immunotherapy’s potential to elicit durable immune responses, potentially reducing the need for prolonged chemotherapy and its associated toxicities.

Researchers also advanced personalized medicine through innovative blood-based assays detecting circulating tumor DNA (ctDNA) and immune profiling from pre-treatment tumor tissue. These tools accurately predicted treatment response, enabling early identification of high-responders who might require minimal post-surgical intervention versus those at risk of progression needing intensified therapy. Dr. Kai-Keen Shiu, the trial’s chief investigator, highlighted the safety and efficacy of pembrolizumab, noting its role in tailoring regimens for high-risk bowel cancers. Professor Marnix Jansen emphasized biological insights into immunotherapy’s mechanisms, while first author Yanrong Jiang stressed ctDNA clearance as a strong prognostic marker for long-term remission. In India, where colorectal cancer is the seventh most common malignancy with over 65,000 new cases yearly (often diagnosed at advanced stages due to limited screening), this approach could transform outcomes, especially for younger patients under 50 facing rising incidence. A patient case, like 73-year-old Christopher Burston, illustrates real-world impact: after three doses, his stage III tumor “melted away,” leading to cancer-free status nearly three years later with minimal side effects. As Indian oncologists grapple with resource constraints, integrating such neoadjuvant strategies and biomarker-driven monitoring could optimize care, potentially improving five-year survival rates that drop from 90% in stage I to 10% in stage IV.