Short course of immunotherapy keeps bowel cancer patients free from recurrence for nearly three years

New results from the NEOPRISM-CRC trial show that 32 patients remained free of cancer for almost three years. None of the patients experienced a recurrence after nearly 33 months of follow-up. This includes people who had small traces of disease remaining after their treatment.

Participants received up to nine weeks of immunotherapy drug pembrolizumab before having surgery. This approach replaces the standard plan of surgery followed by three to six months of chemotherapy. The results suggest this timing may offer more durable control for a specific group of patients.

The trial enrolled people with stage two or three bowel cancer who had a particular genetic profile known as MMR deficient or MSI-high. This genetic make-up affects around 10 to 15 percent of cases in this category. It is equivalent to roughly 2,000 to 3,000 cases diagnosed each year in the UK.

In contrast to the trial results, around 25 percent of patients on the standard approach are expected to relapse within three years. The initial data showed that 59 percent of the immunotherapy group had no detectable signs of disease after treatment and surgery. Researchers say the new findings strengthen confidence in this treatment method for high-risk cases.

Scientists studied blood samples to understand why the treatment worked so well. They found that when tumor DNA disappeared from the blood, patients were much more likely to have no cancer remaining. This discovery could help guide treatment decisions in a practical and timely way.

One participant was Christopher Burston, 73, who had his diagnosis through routine screening in February 2023. He traveled to London for the trial and received three doses of immunotherapy across nine weeks before surgery in May 2023. His doctor told him the cancer had melted away during the procedure.

Dr. Kai-Keen Shiu, the Chief Investigator from UCL Cancer Institute, described the lack of recurrence as extremely encouraging. The team also believes personalized blood tests can predict who will respond to treatment before therapy starts. Professor Marnix Jansen noted these results provide crucial biological insights into why immunotherapy is effective in this setting.

Bowel cancer is the fourth most common cancer in the UK with roughly 44,000 new cases diagnosed each year. Outcomes are generally better when the disease is detected early. Five-year survival drops to 65 percent for stage three bowel cancer and 10 percent for stage four disease.