An oral androgen receptor inhibitor whose clinical testing in metastatic hormone-sensitive prostate cancer (mHSPC) was co-led by Christopher Sweeney, MBBS of Dana-Farber Cancer Institute, has become a standard first-line therapy for men starting hormonal therapy for metastatic prostate cancer.
The drug, enzalutamide (XTANDI), was approved today by the U.S. Food and Drug Administration (FDA) for men with mHSPC - also referred to as metastatic, castration-sensitive prostate cancer (mCSPC). Enzalutamide is a current standard of care in castration-resistant prostate cancer and this approval helps make the drug available to men earlier in their cancer journey.
The benefits of enzalutamide were borne out in the ANZUP-led international randomized, phase III ENZAMET trial, published in the New England Journal of Medicine. Sweeney, study co-chair, presented interim analysis earlier this year during the plenary session at the American Society of Clinical Oncology (ASCO) Annual Meeting. The ENZAMET trial is not listed on the FDA-label but did provide valuable clinical information in the mHSPC setting.
“Through the ENZAMET trial we discovered that adding enzalutamide to testosterone suppression in men with mHSPC can give much better cancer control and longer survival,” said Sweeney. “This is true both for patients with high burden of disease, with multiple bone metastases or liver metastases, as well as men with a lower burden of disease. The new treatment option is especially relevant for men who cannot tolerate chemotherapy and have a lower burden of disease.”
The ENZAMET study is the only study with long enough follow-up and high quality data to show the clear overall survival benefit. It is also the only study to date with any data looking at whether enzalutamide improved the survival of patients when added to testosterone suppression and docetaxel. At this early analysis, there is no survival benefit and it is not recommended to combine with docetaxel at this time.
Men in the ENZAMET study with mHSPC who received testosterone suppression along with enzalutamide survived longer overall than those who were given testosterone suppression along with standard nonsteroidal androgen receptor inhibitors. Among trial participants, 80% of those treated with enzalutamide were alive after three years compared to 72% of the men who received the standard inhibitors. Read more on the ENZAMET trial here: https://www.dana-farber.org/newsroom/news-releases/2019/enzalutamide-improves-survival-for-men-with-metastatic-hormone-sensitive-prostate-cancer/
ENZAMET is a collaborative investigator-initiated study led by the Australian and New Zealand Urogenital and Prostate (ANZUP) Cancer Trials Group and sponsored by the University of Sydney, in collaboration with the Canadian Cancer Trials Group, Dana-Farber and Cancer Trials Ireland. Around the world, 83 research institutions participated. The trial enrolled 1,125 participants and followed them for a median of 34 months. Astellas Pharma provided drug and financial support for ENZAMET but was not involved in the conduct or analysis of the study. Other funding came from Cancer Australia and the Canadian Cancer Society.
Ian Davis is ANZUP chair and Christopher Sweeney is a member of ANZUP’s Scientific Advisory Committee. Both work at institutions that have received research financial support from and consulted for Astellas and Pfizer, who market enzalutamide. Sweeney has received financial compensation for his consultancy from Pfizer and Astellas.