Population Pharmacokinetics of Apalutamide and its Active Metabolite N-Desmethyl-Apalutamide in Healthy and Castration-Resistant Prostate Cancer Subjects

  • Clin Pharmacokinet. 2020 Feb;59(2):229-244. doi: 10.1007/s40262-019-00808-7.
Carlos Pérez-Ruixo  1 ,  Jonás Samuel Pérez-Blanco  1 ,  Caly Chien  2 ,  Margaret Yu  3 ,  Daniele Ouellet  2 ,  Juan-José Pérez-Ruixo  1 ,  Oliver Ackaert  4
Affiliations
  • 1. Janssen Research & Development, Antwerp, Belgium.
  • 2. Janssen Research & Development, Spring House, PA, USA.
  • 3. Janssen Research & Development, Los Angeles, CA, USA.
  • 4. Janssen Research & Development, Antwerp, Belgium. [email protected].
PMID: 31432469 DOI: 10.1007/s40262-019-00808-7
Abstract

Background: Apalutamide is a next-generation Androgen Receptor inhibitor approved for treatment of subjects with high-risk, non-metastatic, castration-resistant prostate Cancer (NM-CRPC).

Objective: The objective of this study was to characterize the population pharmacokinetics of apalutamide and its metabolite N-desmethyl-apalutamide in healthy male and castration-resistant prostate Cancer subjects.

Methods: Plasma concentration data for apalutamide and N-desmethyl-apalutamide from 1092 subjects (seven clinical studies) receiving oral apalutamide (30-480 mg) once daily were pooled for a population pharmacokinetic analysis using a non-linear mixed-effect modelling approach. The impact of clinically relevant covariates was also assessed.

Results: Apalutamide absorption was rapid, and the apparent steady-state volume of distribution was large (276 L), reflecting a wide body distribution. Apalutamide was eliminated slowly, with its apparent clearance increasing from 1.31 L/h after the first dose to 2.04 L/h at steady state. No evidence of time-dependent disposition was observed for N-desmethyl-apalutamide, which was also widely distributed and slowly cleared (1.5 L/h). After 4 weeks of treatment, more than 95% of steady-state exposure of apalutamide and N-desmethyl-apalutamide was reached. At a dose of apalutamide 240 mg/day, apalutamide and N-desmethyl-apalutamide exposure exhibited 5.3- and 85.2-fold accumulation in plasma, respectively. Inter-individual variability in apalutamide apparent clearance is low (< 20%). Among the covariates evaluated, apalutamide and N-desmethyl-apalutamide exposure were statistically associated only with health status, body weight, and albumin concentration, and the effect was low (< 25%).

Conclusions: A population pharmacokinetic modelling approach was successfully applied to describe the pharmacokinetics of apalutamide and N-desmethyl-apalutamide. No clinically relevant covariates were identified as predictors of apalutamide and N-desmethyl-apalutamide pharmacokinetics.

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