Association between CYP2B6 polymorphisms and Nevirapine-induced SJS/TEN: A pharmacogenetics study

Purpose: Nevirapine (NVP) is a non-nucleoside reverse transcriptase inhibitor, widely prescribed for type 1 human immunodeficiency virus infection. A small proportion of individuals treated with NVP experience severe cutaneous adverse events, including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Our aim was to verify whether genetic variability in NVP-metabolizing cytochromes or in transporter genes could be involved in susceptibility to SJS/TEN. Methods: Twenty-seven patients with NVP-induced SJS/TEN and 78 controls, all from Mozambique, were genotyped for the ABCB1 and ABCC10 transporter genes and for CYP2B6, CYP3A4 and CYP3A5 cytochrome gene variants. A case-control and a genotype-phenotype analysis were performed. Results: CYP2B6 G516T and T983C single nucleotide polymorphisms (SNPs) were found to be associated with SJS/TEN susceptibility. The 983C allele in particular was found to be highly associated with a higher risk to develop SJS/TEN [odds ratio (OR) 4.2, P = 0.0047]. The GT haplotype (wildtype for both SNPs) showed a protective effect, with an OR = 0.33 (P = 0.0016). Conclusions: This is the first study showing that genetic variability in a metabolizing enzyme can also contribute to NVP-induced SJS/TEN susceptibility.