A new clinical trial has revealed promising results for colorectal cancer patients, showing that a short course of immunotherapy before surgery may dramatically reduce the risk of cancer recurrence.
Researchers from reported that patients with a specific genetic subtype of colorectal cancer experienced no cancer recurrence even after nearly three years of follow-up.
The study, called NEOPRISM-CRC, was presented at the American Association for Cancer Research (AACR) Annual Meeting 2026. It focused on patients with stage 2 and stage 3 colorectal cancer carrying the MMR-deficient/MSI-high genetic profile — a subtype known to respond poorly to traditional chemotherapy.
Immunotherapy Delivered Before Surgery
Instead of the conventional treatment pathway involving surgery followed by several months of chemotherapy, patients in the trial received nine weeks of immunotherapy using pembrolizumab before surgery.
The results were highly encouraging:
- 59% of patients showed no detectable signs of cancer after treatment and surgery.
- None of the patients experienced cancer recurrence during a median follow-up period of 33 months.
- Even patients with minimal remaining cancer showed no disease progression.
Researchers believe these findings could reshape the future treatment strategy for certain colorectal cancer patients and potentially reduce the need for chemotherapy.
Why the Treatment Worked
MMR-deficient/MSI-high tumors contain a large number of genetic mutations that produce abnormal proteins, making them easier for the immune system to recognize.
Pembrolizumab, an immune checkpoint inhibitor, helps the immune system identify and attack cancer cells more effectively. Administering immunotherapy before surgery may strengthen the body's immune response while the tumor is still present.
The study also used advanced blood-based tumor DNA testing to monitor patient response. Researchers found that patients whose tumor DNA disappeared from the bloodstream after immunotherapy were far more likely to achieve complete remission.
This personalized monitoring approach could help doctors identify which patients may require less treatment and which individuals need closer follow-up or additional therapy.
A Potential Shift in Colon Cancer Care
Colorectal cancer remains one of the most common cancers worldwide and is currently the second leading cause of cancer-related deaths globally. While surgery and chemotherapy remain standard treatments, this study highlights how immunotherapy could offer longer-lasting protection for selected patients.
Experts believe the findings may lead to significant changes in future colorectal cancer treatment guidelines, especially for patients with MMR-deficient/MSI-high tumors.
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