Immunotherapy before surgery prolongs cancer-free survival among certain colon cancer patients

Patients with stage 2 and 3 colon cancer remained cancer free nearly three years after treatment with and immunotherapy drug pembrolizumab (KEYTRUDA®) Image generated by Wix AI

CANCER DIGEST – May 10, 2026 – Patients given a course of immunotherapy prior to surgery for colon cancer remain cancer-free nearly three years later, a new study shows.

The findings of the NEOPRISM-CRC clinical trial led by Chief Investigator Dr. Kai-Keen Shiu of the University College of London were presented at the American Association for Cancer Research (AACR) Annual meeting in San Diego that concluded April 22, 2026.

The trial involved 32 patients with stage two or three bowel cancer, who had a specific genetic profile. The genetic profile represents about 2,000 to 3,000 cases per year in the UK. Patients were given up to nine weeks of immunotherapy with pembrolizumab (KEYTRUDA®) prior to surgery, instead of the conventional three to six months of chemotherapy following surgery.

Initial results of the trial showed that 59 percent of patients had no signs of cancer after the immunotherapy and their planned bowel cancer surgery. With conventional surgery followed by chemotherapy, it is expected that 25 percent of patients will relapse after three years. In this trial, however, after 33 months, none of the patients had experienced a relapse. This includes both those who had no sign of cancer after the immunotherapy and those who still had cancer remaining that did not grow or spread.

“Seeing that no patients have experienced a cancer recurrence after almost three years of follow-up is extremely encouraging," Dr. Shiu said in a press release, "and strengthens our confidence that pembrolizumab is a safe and highly effective treatment to improve outcomes in patients with high-risk bowel cancers. 

In addition to the survival data, the researchers analyzed blood samples from patients to better understand why the treatment is so effective and to better identify those most likely to benefit. By using personalized blood tests, the researchers can both tell early on if a treatment is working, and whether cancer remains in the blood stream.

"These tools could help us tailor our approach, identifying patients who are doing well and may need less therapy before and after surgery versus patients at higher risk of disease progression or relapse who need additional treatment,” Dr. Shiu added.

Sources: University College of London press release