Antiretroviral therapy immunologic non-response in a Brazilian population: association study using pharmaco- and immunogenetic markers

Abstract

Background: Antiretroviral therapy (ART) saved millions from HIV-1 infection and AIDS, but some patients do not experience adequate CD4+ T cells gain despite achieving viral suppression. The genetic component of this condition is not yet completely elucidated.

Objective: To identify predictive genetic markers of immune response to ART.

Methods: Case-control study. Out of 176 HIV-infected patients recruited in the city of Recife, Northeast Brazil, 67 patients with no immunologic response were the cases and the remaining 109 patients who responded were the controls. A set of 94 selected single nucleotide polymorphisms (SNPs) involved in antiretroviral drugs pharmacodynamic pathways and immune system homeostasis were genotyped, while the remaining 48 were ancestry informative markers (AIMs) for controlling for eventual hidden population structure.

Results: Male patients were overrepresented in non-responder group (p=0.01). Non-responders also started with lower absolute CD4+ T cell counts (p<0.001). We found five SNPs significantly associated with the outcome, being three more frequent in non-responders than responders: rs2243250 (IL4) A allele (p=0.04), rs1128503 (ABCB1) A allele (p=0.03) and rs707265 (CYP2B6) A allele (p=0.02), whereas the other two were less frequent in non-responders: rs2069762 (IL2) C allele (p=0.004) and rs4646437 (CYP3A4) A allele (p=0.04).

Conclusion: Some significant univariate associations remained independently associated at multivariate survival analysis modeling, such as pre-treatment CD4+ T cells counts, IL2 and ABCB1 genotypes, and use of protease inhibitors, yielding a predictive model for the probability for immune response. More studies are needed to unravel the genetic basis of ART immunological non-response.

Keywords: Genetic association study; HIV-1; Immunogenetics; Pharmacodynamics; Survival analysis.