Chicago, Illinois—Enzalutamide added to standard of care (ie, testosterone suppression with or without early docetaxel) significantly improved overall survival (OS) in patients with metastatic hormone-sensitive prostate cancer (mHSPC), with fewer benefits seen in those planned to receive early docetaxel, according to study results presented at the 2019 ASCO Annual Meeting.

“Testosterone suppression…is the backbone of treatment for mHSPC. OS is improved by the addition of early docetaxel…or abiraterone to [testosterone suppression],” explained Christopher Sweeney, MBBS, Medical Oncologist, Lank Center for Genitourinary Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, and colleagues.

Between March 31, 2014, and March 24, 2017, Mr Sweeney et al randomized 1125 patients with mHSPC in a 1:1 ratio to receive testosterone suppression plus enzalutamide or nonsteroidal anti-androgen (NSAA).

Overall, 503 men were given early doses of docetaxel, whereas 602 were not. The primary end point of the study was OS.

Findings demonstrated a 3-year OS rate of 80% in the enzalutamide arm versus 72% in the NSAA arm. Furthermore, at 3 years, 64% and 36% of patients remained in the study in each arm, respectively, at 3 years.

Of note, among patients with low-volume disease and without planned docetaxel treatment, the reduced risk for death tied to enzalutamide was more pronounced.

Those with low-volume disease in the enzalutamide arm had a 52% decreased risk for death versus patients taking other NSAAs (3-year OS rates of 90% vs 82%, respectively). In the high-volume disease population, enzalutamide led to a 26% decreased risk for death versus patients taking other NSAAs, with 3-year OS rates of 71% and 63%, respectively.

According to Mr Sweeney and colleagues, patients with no planned early docetaxel treatment had a 49% reduced risk for death with enzalutamide versus NSAA, with 3-year OS rates of 83% and 70%, respectively. Alternatively, patients with planned early docetaxel treatment only had a 9% reduced risk for death with enzalutamide versus NSAA (3-year OS rates, 73% vs 74%, respectively).—Janelle Bradley & Hina Khaliq

Sweeney C, Martin AJ, Zielinski RR, et al. 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. Presented at: the 2019 ASCO Annual Meeting; May 31-June 4, 2019; Chicago, IL. Abstract LBA2.