Oncology News / Literature Review / July-December 2019

Abstract

1.                 Overall survival (OS) results of a phase III randomized trial of standard-of-care therapy with or without enzalutamide for metastatic hormone-sensitive prostate cancer (mHSPC): ENZAMET (ANZUP 1304), an ANZUP-led international cooperative group trial. Testosterone suppression (TS) is the backbone of treatment for metastatic hormone-sensitive prostate cancer (mHSPC). Overall survival is improved by the addition of early docetaxel (DOC) or abiraterone to TS. The randomised phase 3 ENZAMET trial assessed the effects of enzalutamide (ENZA), a potent androgen receptor (AR) inhibitor, versus a nonsteroidal anti-androgen (NSAA: bicalutamide, nilutamide, or flutamide) in addition to SOC in mHSPC. Men (1125) with mHSPC were randomly assigned 1:1 to receive TS plus either ENZA (160 mg daily, by mouth, until clinical disease progression or prohibitive toxicity) or NSAA (conventional NSAA, by mouth until clinical disease progression or prohibitive toxicity). All participants were to receive standard background therapy with a LHRHA or surgical castration, as per standard of care. The choice of the LHRHA or surgical castration was at the discretion of the treating clinician. Randomization was stratified by: volume of disease (high vs low, according to CHAARTED); planned early DOC; planned anti-resorptive therapy, comorbidity score (ACE-27), and study site. The primary endpoint was overall survival. Subgroup analyses to assess possible modulation of the treatment effect were specified a priori and included planned early docetaxel (yes vs no) and volume of disease (high vs low). After a median follow-up of 33 months. Overall survival was prolonged by ENZA. At 3 years, 36% NSAA vs 64% ENZA were still on their assigned study treatment. Serious adverse events (regardless of attribution) within 30 days of study treatment occurred in 42% ENZA vs 34% NSAA, commensurate with the different durations of study treatment. ENZA significantly improved OS when added to SOC in mHSPC while the benefits appeared lower in those planned to receive early DOC.