New prostate cancer drug Keytruda showed promising results in its first major clinical trial to test immunotherapy in some men with advanced prostate cancer.
Researchers from The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust in London gave 258 men with the otherwise untreatable cancer the immunotherapy agent Keytruda (pembrolizumab). After a year, 38% of the men were still alive and 11% are still receiving the antibody, because their cancer stopped growing. Only 5% of men in the trial saw their tumors shrink or go away after treatment.
Prostate cancer affects 1 in 9 men and is the most common non-skin cancer in America, according to the Prostate Cancer Foundation. The one-year survival rate for men diagnosed with late-stage prostate cancer is 75%, according to National Cancer Institute data. That percentage drops to about 26% at five years.
Immunotherapy, which personalizes treatment based on the genetic make-up of tumors, is only successful for a minority of patients, professor Paul Workman, chief executive of the ICR, said in a statement.
"One of the major challenges with immunotherapy is that we don’t have many reliable tests to pick out who will benefit," Workman said. "This new trial has found that testing for mutations in DNA repair genes could be valuable marker of who will respond."
This is among the first trials showing how immunotherapy can benefit men with prostate cancer, professor Johann de Bono, director of the Drug Development Unit at the Institute of Cancer Research said in a statement. In 2010, the U.S. Food and Drug Administration approved Provenge, an immunotherapy treatment made from patients' cells, and the Cancer Research Institute reports there are several immune-based cancer treatments in development.
“Our study has found that immunotherapy can benefit a subset of men with advanced, otherwise untreatable prostate cancer, and these are most likely to include patients who have specific DNA repair mutations within their tumors," he said.
More clinical trials are needed to see if Keytruda could be a widely-used treatment option.
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