Prostate cancer drug delivers benefits before chemotherapy
DURHAM, N.C. -- A drug currently used to treat men with late-stage prostate cancer proved effective in stemming disease progression and extending survival in patients who had not yet received chemotherapy, according to results from a large international study that included Duke Cancer Institute researchers.
A comprehensive analysis of the study’s results were published June 1, 2014, in the online edition of the New England Journal of Medicine and presented at the American Society of Clinical Oncology annual meeting in Chicago.
The study found that participants treated with enzalutamide had an 81 percent reduction in the risk of tumor progression or death and a 29 percent reduction in the risk of death. The oral medication also helped prevent the spread of the disease to the bones, delayed the need for chemotherapy, and reduced evidence of prostate cancer in the bloodstream. Enzalutamide also resulted in a high level of SA responses, radiographic responses and quality of life improvements.
“These results suggest that the earlier use of enzalutamide may result in substantial advantages to men facing this form of aggressive prostate cancer, without major side effects other than fatigue and hot flushing,” said study co-author Andrew Armstrong, M.D., associate professor of medicine and surgery at Duke Cancer Institute. “Further ongoing studies in men with recurrent prostate cancer and who lack metastatic disease should clarify when enzalutamide should be optimally given.”
The large, multi-site study included 1,717 research participants enrolled at 207 sites globally from 2010 to 2012; 872 received enzalutamide while the others received a placebo. All enrolled patients had metastatic prostate cancer that was worsening despite treatment with traditional hormone therapy. None had yet received chemotherapy.
The trial, named PREVAIL, was concluded early, after a planned interim analysis, because of overwhelming response to the treatment. At this point, 72 percent of enzalutamide patients and 63 percent of placebo patients were alive at the trial cutoff date showing a 29 percent overall improvement in survival.
Fatigue and hypertension were among the most common clinically relevant side effects.
Prostate cancer is the most common form of cancer in men and the second leading cause of cancer-related death in the U.S. and the sixth-leading cause of cancer-related death among men worldwide. Hormone therapies are used to treat prostate cancer that isn’t responding to radiation or surgery or has already spread beyond the prostate gland.
Male hormones, called androgens, cause prostate cancer cells to grow. Hormone therapies, known as androgen deprivation therapies, help arrest the disease by reducing a patient’s androgen levels. Enzalutamide works differently than other hormone therapies; rather than reducing hormone levels, it blocks hormone binding to the androgen receptor – an essential step in hormone action.
Enzalutamide, which is taken as four pills once per day, is already approved by the Food and Drug Administration for men whose disease has not been stopped by other treatments including, surgery, radiation, androgen deprivation therapy and chemotherapy.
“Based on the study results, this drug could fill an important gap in prostate cancer treatment today. The strong response to this new use of enzalutamide shows that it can provide a viable, less toxic alternative to chemotherapy in staving off the disease in men who aren’t responding to standard, first-line hormonal treatments,” said Tomasz Beer, M.D., the lead author on the study and deputy director of the Knight Cancer Institute at Oregon Health & Science University.
Researchers who contributed to the study were from Memorial Sloan-Kettering Cancer Center and Weill Cornell Medical College, Institut Gustave Roussy at the University of Paris Sud, San Camillo and Forlanini Hospitals, Seattle Cancer Care Alliance, Rigshospitalet at the University of Copenhagen, Medivation Inc., Vall d’Hebron University Hospital, Medical Oncology Department, and Vall d’Hebron Institute of Oncology, Guy's Hospital, London, UK, Monash University and Eastern Health, Royal Marsden Hospital and Institute of Cancer Research, UC Davis Comprehensive Cancer Center, Princess Margaret Cancer Center, Asan Medical Center, Nippon Medical School, Icon Cancer Care, Charité-Universitätsmedizin Berlin, Astellas Pharma Global Development Inc., University of Montreal Health Center/CRCHUM, Dana-Farber Cancer Institute, Cross Cancer Institute and University of Alberta and Cliniques Universitaires Saint-Luc.
Astellas and Medivation are collaborating on a comprehensive global development program that includes studies of enzalutamide across the full spectrum of advanced prostate cancer as well as advanced breast cancer. The companies jointly commercialize enzalutamide capsules in the United States and Astellas is responsible for all global manufacturing and regulatory filings, as well as commercializing the drug outside the United States.