Efficacy and safety of enzalutamide in patients 75 years or older with chemotherapy-naive metastatic castration-resistant prostate cancer: results from PREVAIL

Ann Oncol. 2016 Feb;27(2):286-94. doi: 10.1093/annonc/mdv542. Epub 2015 Nov 16.

Abstract

Background: Prostate cancer disproportionately affects older men. Because age affects treatment decisions, it is important to understand the efficacy and tolerability of therapies for advanced prostate cancer in elderly men. This analysis describes efficacy and safety outcomes in men aged ≥75 years who received enzalutamide, an androgen receptor inhibitor, in the phase III PREVAIL trial.

Patients and methods: PREVAIL was a randomised, double-blind, multinational study of oral enzalutamide 160 mg/day (N = 872) versus placebo (N = 845) in chemotherapy-naive men with metastatic castration-resistant prostate cancer. Overall survival (OS) and radiographic progression-free survival (rPFS) were coprimary end points. Subgroup analysis of men aged ≥75 years (elderly) and men aged <75 years was pre-specified for the coprimary end points and adverse events (AEs).

Results: Among 609 elderly patients (35%) who participated in PREVAIL, median treatment duration was 16.6 and 5.0 months in the enzalutamide and placebo arms, respectively. In the elderly subgroup, OS was greater with enzalutamide than with placebo [32.4 months (95% confidence interval (CI) 27.7-not yet reached] versus 25.1 months (95% CI 22.6-28.0); hazard ratio (HR) = 0.61 (95% CI 0.47-0.79); P = 0.0001], as was rPFS [not yet reached (95% CI 12.3-not yet reached) versus 3.7 months (95% CI 3.6-5.3); HR = 0.17 (95% CI 0.12-0.24); P < 0.0001]. Irrespective of treatment assignment, incidence of AEs was similar between the two age groups, except for an overall higher incidence of falls among elderly patients than younger patients [84/609 (13.8%) versus 62/1106 (5.6%)] and among elderly patients receiving enzalutamide than those receiving placebo [61/317 (19.2%) versus 23/292 (7.9%)].

Conclusions: Elderly men benefited from treatment with enzalutamide in terms of OS and rPFS. Enzalutamide was well tolerated in the elderly subgroup and those aged <75 years. Age and enzalutamide treatment were associated with a higher incidence of falls.

Clinical trial identifier: NCT01212991, ClinicalTrials.gov.

Keywords: PREVAIL trial; elderly patients; enzalutamide; metastatic castration-resistant prostate cancer.

Publication types

  • Clinical Trial, Phase III
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Accidental Falls / statistics & numerical data
  • Adult
  • Aged
  • Aged, 80 and over
  • Androgen Receptor Antagonists / adverse effects
  • Androgen Receptor Antagonists / therapeutic use*
  • Antineoplastic Agents / adverse effects
  • Antineoplastic Agents / therapeutic use*
  • Disease-Free Survival
  • Double-Blind Method
  • Humans
  • Male
  • Middle Aged
  • Phenylthiohydantoin / adverse effects
  • Phenylthiohydantoin / analogs & derivatives*
  • Phenylthiohydantoin / therapeutic use
  • Placebos
  • Prostatic Neoplasms, Castration-Resistant / drug therapy*
  • Prostatic Neoplasms, Castration-Resistant / mortality
  • Prostatic Neoplasms, Castration-Resistant / pathology

Substances

  • Androgen Receptor Antagonists
  • Antineoplastic Agents
  • Placebos
  • Phenylthiohydantoin
  • enzalutamide

Associated data

  • ClinicalTrials.gov/NCT01212991