Researchers at University College London (UCL) and University College London Hospitals (UCLH) have discovered that an immunotherapy drug, pembrolizumab, significantly increases the number of patients who are cancer-free after surgery for bowel cancer, according to interim results from the NEOPRISM-CRC phase II clinical trial presented at the American Society of Clinical Oncology (ASCO) Annual Meeting 2024.
The study investigated whether pembrolizumab could improve outcomes for patients with stage two or stage three MMR deficient/MSI-High bowel cancer. This genetic profile, present in 10–15 percent of stage two or three bowel cancer patients, represents about 2,000–3,000 cases annually in the U.K. The trial included 32 patients from five U.K. hospitals who were treated with pembrolizumab for nine weeks before surgery instead of the usual combination of surgery and chemotherapy.
The results were remarkable: over 50 percent of the patients treated with pembrolizumab showed no signs of cancer after surgery, a significant improvement compared to just four percent in similar studies involving preoperative chemotherapy. All patients remained cancer-free for many months post-surgery, with the median cancer-free period being 9.7 months, ranging from 5.3 to 19 months.
Kai-Keen Shiu, MD, PhD, the chief investigator of the trial from UCL Cancer Institute and a consultant medical oncologist at UCLH, highlighted the potential of pembrolizumab as a safe and highly effective treatment for improving outcomes in high-risk bowel cancer patients.
“We need to wait to see whether the patients in our trial remain cancer-free over a longer period of time, but initial indications are extremely positive,” Shiu said in a press statement.
Professor Mark Saunders from The Christie NHS Foundation Trust, a co-investigator in the study, described the treatment as a potential “game-changer” for patients with the appropriate genetic make-up. He emphasized that immunotherapy before surgery could significantly improve outcomes and reduce the need for conventional postoperative chemotherapy, improving patient quality of life.
The research also explored whether tumor mutation burden could serve as a useful biomarker for predicting individual risk, potentially guiding more personalized treatment strategies in the future.
“More work needs to be done to assess pembrolizumab before it could be considered standard treatment, but given the quality of the outcomes in this trial I think it’s possible that we could see it in the clinic within a couple of years if subsequent trials are similarly successful,” said Marnix Jansen, who leads the translational research on the trial.
The investigators believe that the NEOPRISM-CRC trial, funded by Merck Sharp and Dohme and conducted by the CR UK & UCL Cancer Trials Center, represents a significant step forward in the treatment of bowel cancer. The study’s success underscores the potential of immunotherapy to transform cancer care, particularly for patients with specific genetic profiles, offering new hope for more effective and less invasive treatment options.
