CHICAGO – Adding the oral androgen receptor inhibitor enzalutamide to standard first-line testosterone suppression delays progression and improves survival in men with metastatic hormone-sensitive prostate cancer (mHSPC), according to “practice-informing” interim results from the randomized phase 3 ENZAMET trial.
The survival rate at 3 years in 563 men with mHSPC who were enrolled in the international trial and who received early testosterone suppression and enzalutamide was 80%, compared with 72% among 562 men who received testosterone suppression and standard nonsteroidal antiandrogen therapy with or without docetaxel, study cochair Christopher Sweeney, MBBS, reported at the annual meeting of the American Society of Clinical Oncology (Abstract LBA2).
The findings of the Australian and New Zealand Urogenital and Prostate (ANZUP) Cancer Trials Group study (ANZUP 1304/ENZAMET) were published simultaneously in the New England Journal of Medicine.
“So ... we’re moving forward by going backwards in the disease setting where the disease is more sensitive and responds better to therapy,” Dr. Sweeney, of Dana-Farber Cancer Institute’s Lank Center for Genitourinary Oncology and professor of medicine at Harvard Medical School, Boston, explained in this video interview.
He also described the future directions for the research – in particular the need for longer follow-up to clarify the effects of docetaxel in this setting – and how the current findings will be reflected in his own management of patients with prostate cancer.
The findings have immediate implications for practice, ASCO expert Neeraj Agarwal, MD, professor of medicine and investigator at the Huntsman Cancer Institute, University of Utah, Salt Lake City, said during a press briefing at the meeting.
“In my view, using enzalutamide early on will allow our patients to avoid chemotherapy and steroids for many years, and thus, hopefully, improve their quality of life,” he said, noting that the findings are particularly exciting when considered in the context of the “equally impressive margin of benefit” seen with the similar drug apalutamide in the TITAN trial, which was presented separately during the ASCO meeting.
“One study is encouraging, but two large studies ... demonstrating similar findings, is even better,” he said. “This increases my confidence that targeting [the androgen receptor] is the optimal approach for newly diagnosed patients with advanced prostate cancer.”
Dr. Sweeney reported relationships (stock and other ownership interests, consulting or advisory roles, research funding to his institution, and/or patents/royalties/other intellectual property) with Leuchemix, Amgen, Astellas Pharma, AstraZeneca, Bayer, Genentech/Roche, Janssen Biotech, Pfizer, Sanofi, Dendreon, Sotio, and Exelixis. Dr. Agarwal reported consultancy or research for Pfizer, Novartis, Exelixis, Eisai, Genentech, Medivation, Clovis, Merck, Bayer, GlaxoSmithKline, AstraZeneca, EMD Serono, and Bristol-Myers Squibb.