No Clinical Impact of CYP3A5 Gene Polymorphisms on the Pharmacokinetics and/or Efficacy of Maraviroc in Healthy Volunteers and HIV-1-Infected Subjects

Abstract

Maraviroc is a C-C chemokine receptor type-5 antagonist approved for the treatment of HIV-1. Previous studies show that cytochrome P450 3A5 (CYP3A5) plays a role in maraviroc metabolism. CYP3A5 is subject to a genetic polymorphism. The presence of 2 functional alleles (CYP3A5*1/*1) confers the extensive metabolism phenotype, which is rare in whites but common in blacks. The effect of CYP3A5 genotype on maraviroc and/or metabolite pharmacokinetics was evaluated in 2 clinical studies: a post hoc analysis from a phase 2b/3 study (NCT00098293) conducted in 494 HIV-1-infected subjects (study 1) in which the impact on maraviroc efficacy in 303 subjects was also assessed, and a study conducted in 47 healthy volunteers (study 2). In study 2 (NCT02625207), extensive metabolizers had 26% to 37% lower mean area under the concentration-time curve compared with poor metabolizers (no CYP3A5*1 alleles). This effect diminished to 17% in the presence of potent CYP3A inhibition. The effect of CYP3A5 genotype was greatest in the formation of the metabolite (1S,2S)-2-hydroxymaraviroc. In study 1, the CYP3A5*1/*1 genotype unexpectedly had higher maraviroc area under the curve predictions (20%) compared with those with no CYP3A5*1 alleles. The reason for this disparity remains unclear. The proportions of subjects with viral loads <50 and <400 copies/mL for maraviroc were comparable among all 3 CYP3A5 genotypes. In both studies maraviroc exposures were in the range of near-maximal viral inhibition in the majority of subjects. These results demonstrate that although CYP3A5 contributes to the metabolism of maraviroc, CYP3A5 genotype does not affect the clinical response to maraviroc in combination treatment of HIV-1 infection at approved doses.

Keywords: C-C chemokine receptor type-5 antagonist; CYP3A inhibition; CYP3A5 genotype; MERIT study; cytochrome P450; maraviroc.

© 2018, The Authors. The Journal of Clinical Pharmacology published by Wiley Periodicals, Inc. on behalf of American College of Clinical Pharmacology.

Figures

Figure 1

Effect of CYP3A5 genotype on estimated maraviroc Cavg in HIV‐infected subjects (study 1). Upper plot, all maraviroc subjects (n = 494); middle plot, whites (n = 311); lower plot, blacks (n = 138). Dashed line represents median Cavg for distribution; solid reference line represents Cavg = 75 ng/mL, exposure associated with near‐maximal virologic efficacy.28 Cavg indicates average plasma concentration; EM, extensive metabolizer (2 CYP3A5*1 alleles); IM, intermediate metabolizer (1 CYP3A5*1 allele); PM, poor metabolizer (no CYP3A5*1 alleles).

Figure 2

Maraviroc plasma concentration‐time profiles by CYP3A5 genotype (study 2). A, Maraviroc plasma concentrations following maraviroc 300 mg twice‐daily dosing in part 1. B, Maraviroc plasma concentrations following maraviroc 150 mg + darunavir/cobicistat 800/150 mg once‐daily dosing in part 2. EM indicates extensive metabolizer (2 CYP3A5*1 alleles); IM, intermediate metabolizer (1 CYP3A5*1 allele); PM, poor metabolizer (no CYP3A5*1 alleles).

Figure 3

Maraviroc Cavg exposure by CYP3A5 genotype with and without CYP3A inhibition (study 2). Solid reference line represents Cavg = 75 ng/mL, exposure associated with near‐maximal virologic efficacy in study 1.28 Each boxplot shows the interquartile range with the median (horizontal line) and mean (×) Cavg values indicated. Whiskers show the minimum and maximum values. The circles represent individual scores. Cavg indicates average plasma concentration; EM, extensive metabolizer (2 CYP3A5*1 alleles); IM, intermediate metabolizer (1 CYP3A5*1 allele); MVC, maraviroc; PM, poor metabolizer (no CYP3A5*1 alleles).