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.