Enzalutamide Improves Survival in Castration-Resistant Prostate Cancer

By Gene Emery

June 01, 2020

(Reuters Health) - Adding enzalutamide to androgen-deprivation therapy extends overall survival by 27% in men with aggressive prostate cancer, researchers reported Friday.

The final results of the PROSPER study show that the drug typically provided an extra 11 months of life in men with non-metastatic, castration-resistant disease and a PSA level that was doubling every 10 months or less.

Earlier results of the trial had shown a 71% reduction in metastasis-free survival.

"It's really nice for physicians to see that metastasis-free survival really correlates with improved overall survival," chief author Dr. Cora Sternberg, clinical director of the Englander Institute for Precision Medicine at Weill Cornell Medicine in New York City told Reuters Health in a telephone interview.

The new data were unveiled online during the American Society of Clinical Oncology's 2020 Virtual Scientific Program and published by The New England Journal of Medicine.

The phase 3 study included 1,401 men who continued to receive androgen-deprivation therapy.

Median overall survival for the 933 patients receiving 160 mg of enzalutamide daily was 67.0 months versus 56.3 months among placebo recipients, a 27% reduction in the risk of death over the duration of the study (P=0.001).

Those 11 extra months would cost roughly $834,000, according to price information on drugs.com. The drug is sold under the brand name Xtandi by co-developers Pfizer and Astellas Pharma. The companies analyzed the data and provided it to the authors.

The overall rates of adverse events of grade 3 or higher per 100 patient-years was 17 with enzalutamide and 20 with placebo.

"Any serious adverse events were really not more frequent in the enzalutamide arm than they were in the placebo arm," said Dr. Sternberg.

Fatigue and musculoskeletal problems were the most common side effects. But falls, fractures, hypertension, and death from cardiovascular causes were also more common in the treatment group.

"The rate of cardiovascular events was 3 per 100 patient-years with enzalutamide as compared to 2 per 100 patient-years with placebo," Dr. Sternberg said. "Ischemic heart disease rates were 3 per 100 patient-years with enzalutamide and 1 per 100 patient years with placebo."

"Although none of the cardiovascular deaths were attributed to enzalutamide by the investigators," her team said, "physicians should be aware of the increased risk when determining whether a patient with pre-existing cardiovascular disease should receive enzalutamide, and patients receiving this treatment should be followed closely."

SOURCE: https://bit.ly/2XIkfGb The New England Journal of Medicine, online May 29, 2020.