An immunotherapy ‘gamechanger’ drug that ‘melts away’ tumors dramatically increases the chances of a cure for colon cancer and could even replace the need for surgery, doctors say.
Pembrolizumab targets and blocks a specific protein on the surface of immune cells that then seek out and destroy cancer cells.
Giving the drug before surgery instead of chemotherapy led to a huge increase in the number of patients declared cancer-free, a clinical trial found. The results were presented at the annual meeting of the American Society of Clinical Oncology (ASCO), the world’s largest cancer conference.
The study was led by University College London, University College London Hospital, the Christie NHS Foundation Trust in Manchester, St James’s University Hospital in Leeds, University Hospital Southampton and the University of Glasgow.
Prof. Mark Saunders, a consultant clinical oncologist at Christie, said the study results were “really exciting”.
“Immunotherapy prior to surgery could well become a ‘game changer’ for these patients with this type of cancer. Not only is the outcome better, but it also spares patients the need for more conventional chemotherapy, which often has more side effects.
“In the future, immunotherapy could even replace the need for surgery.”
Colon cancer is the second leading cause of cancer-related deaths worldwide. According to the World Health Organization, there are more than 1.9 million new cases and more than 900,000 deaths every year.
In the trial, funded by Merck Sharp and Dohme and sponsored by University College London, researchers recruited 32 patients with stage two or three bowel cancer and a particular genetic profile (MMR-deficient/MSI-high bowel cancer) from five hospitals in the UK.
About 15% of patients with stage two or three colon cancer have this specific genetic makeup.
Patients received pembrolizumab, also known as Keytruda, for nine weeks before surgery, instead of the usual treatment of chemotherapy and surgery, and were then followed over time.
The results show that 59% of patients showed no signs of cancer after treatment with pembrolizumab, while the remaining 41% of patients had any cancer removed during surgery.
All patients in the study were cancer-free after treatment. When standard chemotherapy was given to patients with this genetic profile, less than 5% had no signs of cancer after surgery, UCL said.
In coming years, the study will also assess overall survival and relapse rates.
The approach also meant that patients did not need postoperative chemotherapy, which has side effects and is difficult to tolerate.
Dr. Kai-Keen Shiu, principal investigator of the study and consultant medical oncologist at UCLH, said: “Our results indicate that pembrolizumab is a safe and highly effective treatment to improve outcomes in patients at high risk of bowel cancer, increasing the chance of a cure increases. the disease in its early stages.”
Shiu cautioned that the team would have to wait to see if patients in the trial remained cancer-free over a longer period of time, but said initial indications were “extremely positive.”
“Immunotherapy can cause tumors to disappear before surgery. If you melt out the cancer before surgery, you normally triple the chances of survival,” Shiu added. “If patients have a complete response to pembrolizumab, it can triple your chance of survival.
“Patients do not need chemotherapy afterwards, so they avoid all those side effects.”
Dr. Marnix Jansen, a clinical scientist at the UCL Cancer Institute, said more work needs to be done to assess pembrolizumab before it can be considered standard treatment. “But given the quality of the results of this study, I think it is possible that we could see this in the clinic within a few years if subsequent studies are equally successful.”