Enzalutamide improves survival for men with metastatic hormone-sensitive prostate cancer
Enzalutamide, an oral androgen receptor inhibitor, can increase results for men with metastatic hormone-sensitive prostate cancer (mHSPC), according to a large study presented by Christopher Sweeney, MBBS of the Lank Center for Genitourinary Oncology Institute-Farber Cancer Institute, in America. Annual Meeting of the Clinical Oncology Society (ASCO).
An interim analysis of the international ANZUP randomized trial led by ANZUP, phase III showed that among men with mHSPC who received testosterone suppression, those who were also given enzalutamide lasted longer overall than those who were also given standard nonsteroidal androgen receptor inhibitors. Among the trial participants, 80% of those treated with enzalutamide were alive after three years compared with 72% of men who received standard inhibitors.
"These findings really provide practical information, adding drug options that are effective in treating mHSPC," said lead researcher Sweeney who presented the results during the ASCO plenary session. The plenary session featured four studies that were considered to have the greatest potential impact on patient care, from more than 6,000 abstracts presented at the 5-day conference. The details are published simultaneously in the New England Journal of Medicine.
"Adding enzalutamide to testosterone suppression in men with mHSPC can provide better cancer control and longer survival," Sweeney said. "This applies both to patients with a high disease burden, with multiple bone metastases or liver metastases, as well as men with a lower disease burden. This new treatment option is very relevant for men who cannot tolerate chemotherapy and have a lower disease burden. "
"The benefits of enzalutamide have been established for prostate cancer that no longer responds to hormone therapy," said Ian D. Davis, MBBS, PhD, ANZUP chair and study co-chair. "The true results in patients who started hormone therapy, noted patients had a 60% increase in the time needed to detect cancer growing again along with a 33% increase in the possibility of survival, much higher than we expected."
One important question that the trial tried to understand was how well enzalutamide was compared to, or combined with, docetaxel, the chemotherapy drug approved for the conditions given to about 45% of trial participants. ENZAMET shows that in this population, "enzalutamide and docetaxel are both active and are reasonable alternatives but have different side effects, costs, risks and benefits," Sweeney said.
Preliminary analysis showed that among men with a lower burden of metastatic disease given testosterone suppression, enzalutamide might offer more benefits than docetaxel, Sweeney said. However, he warned that these findings need to be investigated further. Combining testosterone suppression with enzalutamide and docetaxel delay the time for the disease to develop, but the researchers must follow up on the trial participants to see if this triplet combination also improves overall quality of life and survival.
Overall in ENZAMET, side effects known to be associated with enzalutamide were observed and resulted in a modest increase in side effects compared to men who received one of the standard non-steroidal anti-androgens.
The National Cancer Institute estimates that 175,000 men will be diagnosed with prostate cancer and 32,000 men will die from this disease this year in the United States. About 95% of men diagnosed with the disease are localized through screening prostate-specific antigen (PSA). Most were cured by surgery or radiation, and some did not need treatment, Sweeney said.
The remaining 5% of patients initially present with very aggressive disease, and many other patients relapse after treatment for localized diseases but tend to have slower progression of the disease. U.S. Food and Drug Administration has approved enzalutamide for men where the disease continues to develop, both for men who have been treated with docetaxel and men who have not. Other hormone treatments
