Clinical Pharmacokinetic Studies of Enzalutamide

Clin Pharmacokinet. 2015 Oct;54(10):1043-55. doi: 10.1007/s40262-015-0271-5.

Abstract

Background and objectives: Oral enzalutamide (160 mg once daily) is approved for the treatment of metastatic castration-resistant prostate cancer (mCRPC). This article describes the pharmacokinetics of enzalutamide and its active metabolite N-desmethyl enzalutamide.

Methods: Results are reported from five clinical studies.

Results: In a dose-escalation study (n = 140), enzalutamide half-life was 5.8 days, steady state was achieved by day 28, accumulation was 8.3-fold, exposure was approximately dose proportional from 30-360 mg/day, and intersubject variability was ≤30 %. In a mass balance study (n = 6), enzalutamide was primarily eliminated by hepatic metabolism. Renal excretion was an insignificant elimination pathway for enzalutamide and N-desmethyl enzalutamide. In a food-effect study (n = 60), food did not have a meaningful effect on area under the plasma concentration-time curve (AUC) of enzalutamide or N-desmethyl enzalutamide, and in an hepatic impairment study, AUC of the sum of enzalutamide plus N-desmethyl enzalutamide was similar in men with mild (n = 6) or moderate (n = 8) impairment (Child-Pugh Class A and B) versus men with normal hepatic function (n = 14). In a phase III trial, an exposure-response analysis of steady-state predose (trough) concentrations (C trough) versus overall survival (n = 1103) showed that active treatment C trough quartiles for 160 mg/day were uniformly beneficial relative to placebo, and no threshold of C trough was associated with a statistically significant better response.

Conclusions: Enzalutamide has predictable pharmacokinetics, with low intersubject variability. Similar efficacy was observed in patients across the concentration/exposure range associated with a fixed oral dose of enzalutamide 160 mg/day.

Trial registration: ClinicalTrials.gov NCT00510718 NCT00974311 NCT01901133 NCT01911715.

Publication types

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

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antineoplastic Agents / administration & dosage*
  • Antineoplastic Agents / blood
  • Antineoplastic Agents / pharmacokinetics*
  • Biotransformation
  • Dose-Response Relationship, Drug
  • Drug Administration Schedule
  • Food-Drug Interactions
  • Humans
  • Male
  • Middle Aged
  • Phenylthiohydantoin / administration & dosage
  • Phenylthiohydantoin / analogs & derivatives*
  • Phenylthiohydantoin / blood
  • Phenylthiohydantoin / pharmacokinetics
  • Prostatic Neoplasms, Castration-Resistant / blood
  • Prostatic Neoplasms, Castration-Resistant / drug therapy*
  • Prostatic Neoplasms, Castration-Resistant / metabolism

Substances

  • Antineoplastic Agents
  • Phenylthiohydantoin
  • enzalutamide

Associated data

  • ClinicalTrials.gov/NCT00510718
  • ClinicalTrials.gov/NCT00974311
  • ClinicalTrials.gov/NCT01901133
  • ClinicalTrials.gov/NCT01911715