Landmark clinical trial reports 33% prostate cancer survival benefit from novel hormone therapy

A landmark Australian-led clinical trial has shown that hormone therapy with a drug called enzalutamide can improve the survival of some men with advanced, hormone‐sensitive prostate cancer.

Professor Ian Davis, Head of the Monash University Eastern Health Clinical School and chair of the Australian and New Zealand Urogenital and Prostate Cancer Trials Group (ANZUP) which led the ENZAMET trial, said it showed men with this sort of cancer who receive enzalutamide with standard treatment have a 33% improvement in survival compared to men receiving standard treatment alone.

Five‐year survival from prostate cancer in Australia is high (95%) but this mainly represents men with earlier stages of the disease.

Professor Davis, said metastatic prostate cancer was still the second‐leading cause of cancer death in Australian men after lung cancer.

“On current trends, around 3,500 Australian men will die from prostate cancer this year,” Professor Davis said, “so it is urgent that we research new treatments and ways of using established treatments better.”

“The benefits of enzalutamide had already been established for prostate cancers that are no longer responding to hormonal therapy. We found that by using enzalutamide in patients starting hormonal therapy, there was a 60% improvement in the time it takes to detect the cancer growing again along with a 33% reduced chance of dying.

“Prostate cancer is complex and so are the benefits, side effects and risks of multiple treatments.

“Clinical trials are the most effective way of determining which treatments, alone or in combination, will provide the greatest survival benefit to the patient with the least adverse outcomes.”

Professor Christopher Sweeney, co‐chair with Professor Davis of the ENZAMET trial, said, “This is one of the most significant findings yet in clinical trials for men with metastatic hormone‐sensitive prostate cancer – and a great example of effective international collaboration.”

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About ENZAMET
ENZAMET (ANZUP 1304, NCT02446405, CCTG PR17) is a global collaborative investigator‐initiated trial led by ANZUP and sponsored by the University of Sydney, in collaboration with the Canadian Cancer Trials Group, Dana‐Farber Cancer Institute, and Cancer Trials Ireland (enrolling patients from Ireland and the United Kingdom). The University of Sydney NHMRC Clinical Trials Centre provided central study coordination. Astellas Pharma provided drug and financial support but was not involved in study conduct or data analysis.

The side effects of addition of enzalutamide to standard of care were overall similar to what has been experienced with enzalutamide in previous clinical trials.

Full results from the ENZAMET study were presented in the Plenary Session at the American Society of Clinical Oncology (ASCO) Annual Scientific Meeting in Chicago on Sunday 2 June 2019. The details were published simultaneously in the New England Journal of Medicine. For additional study information, visit https://clinicaltrials.gov/ct2/show/NCT02446405?term=enzamet&rank=1

About Metastatic Hormone‐Sensitive Prostate Cancer
Metastatic prostate cancer is cancer that has spread from the prostate to other parts of the body which can be seen on conventional CT and/or bone scans. Patients with metastatic hormone sensitive prostate cancer are patients who are starting treatment for metastatic disease and will most likely respond to suppression of the male sex hormone testosterone. Recent advances have shown some patients live longer when docetaxel or abiraterone (an agent that suppresses other male hormones) are added to the testosterone suppression. ENZAMET is the first trial to show a survival benefit from addition of enzalutamide, and the first to include patients receiving docetaxel chemotherapy at the same time.

About ANZUP
ANZUP is the leading cancer‐cooperative clinical trials group that brings together all of the professional disciplines and groups involved in researching and treating urogenital cancers and conduct high quality clinical research. ANZUP identifies gaps in evidence and areas of clinical need, collaborate with the best clinicians and researchers in GU cancer and communicate frequently and effectively with the broader community along the way. ANZUP receives valuable infrastructure support from the Australian Government through Cancer Australia.

Professor Davis is ANZUP chair and Professor 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*. Professor Sweeney has received financial compensation for his consultancy from Pfizer and Astellas.

*Note that Astellas and Pfizer co‐market enzalutamide in the USA, elsewhere in the world enzalutamide is marketed by Astellas