Men with non-metastatic castrate-resistant prostate cancer and quickly rising prostate-specific antigen (PSA) levels receive hormone treatments to reduce the testosterone their cancer feeds on, but their cancers have become resistant to treatment at that point. While there was previously no treatment for such patients, a new double-blind, randomized phase III trial shows a drug currently used to treat men with metastatic advanced prostate cancer significantly lowered the risk of metastasis and death when used in such cases. The study, done by Northwestern Medicine clinical researchers, is published today in the New England Journal of Medicine.
The drug, enzalutamide, works by targeting androgen receptors on cancer cells, starving the cell of testosterone and other male hormone-like substances. Researchers tested the drug in a trial that included approximately 1,400 men with PSA levels that had doubled in 10 months or less and were taking androgen therapy. For every two patients that got the drug, one got a placebo. Enzalutamide was administered for a median of 18.4 months and placebo for 11.1 months. Patients who got placebo received the drug after the trial finished.
Men who took enzalutamide, had a 71% lower risk of metastasis or death than those who took the placebo over the duration of the trial. They also had delayed cancer re-appearance of almost two years compared to those taking a placebo. Those taking the drug had a greater decline in PSA and needed fewer additional anticancer treatments.
"By treating men earlier when they have less cancer, the drug can be more effective," said lead study author Dr. Maha Hussain. "It's like weeds in the garden. It's easier to control one weed than a garden full of them." The team plans to continue trials to gather further long-term data.