Single-nucleotide polymorphisms in ABC drug transporters alter expression and circulating tenofovir in healthy South African women exposed to pre-exposure prophylaxis.

Aim: We investigated if single-nucleotide polymorphisms (SNPs) in ATP-binding cassette (ABC) drug transporters alter gene expression and tenofovir disposition in South African women taking Truvada^® for HIV prevention. Materials & methods: In 393 women, real-time PCR was used to determine the associations between six SNPs in ABC transporter genes, mRNA expression and circulating-tenofovir. Results: Univariable and multivariable analyses showed that CT and TT relative to CC genotypes for the ABCC4(3463C/T) SNP had significantly higher tenofovir levels. In contrast, the AA genotype for the ABCC4(4976A/G) SNP showed significantly less tenofovir, while mRNA expression was increased. Conclusion: SNPs in the ABCC4 gene may differentially affect gene expression and circulating tenofovir. Their impact may inform on low pre-exposure prophylaxis efficacy and discern effective drugs in clinical trials of African women enriched for certain genotypes.