CETP inhibition and ADCY9 genotype: evidence of a qualitative pharmacogenetic interaction in cardiovascular disease?

BackgroundCETP inhibitors raise circulating concentrations of HDL-cholesterol, and potent inhibitors also lower non-HDL-cholesterol and risk of vascular disease. Previous genome-wide pharmacogenetic analysis of a phase III randomized controlled trial (RCT) of the CETP inhibitor, dalcetrapib, found variants in ADCY9 to associate with response to treatment. More recently, findings from a pharmacogenetic analysis of the CETP inhibitor evacetrapib reported a lack of such an association.\n\nAimsTo clarify the totality of evidence on whether ADCY9 genotype modifies the treatment response to CETP inhibition on risk of major adverse cardiac events through systematic review and meta-analysis.\n\nMethodsWe searched PubMed on 22nd May 2018 to identify RCTs of CETP inhibition that reported vascular disease effect estimates stratified by ADCY9 genotype. Stratum-specific estimates were pooled using fixed effect meta-analysis. Tests of heterogeneity between, and trend across, genotypic strata were assessed using Chi2.\n\nResultsNine studies were identified from PubMed, of which two (dal-OUTCOMES and ACCELERATE) were RCTs reporting the treatment response to CETP inhibition by ADCY9 genotype, and fulfilled the inclusion criteria. In meta-analysis of dal-OUTCOMES and ACCELERATE, treatment with a CETP inhibitor was associated with a relative risk (RR) for major adverse cardiac events of RR 0.80 (95%CI, 0.65-0.99) in carriers of ADCY9 rs1967309 AA. For carriers of AG, the corresponding estimate was a RR of 1.01 (95%CI, 0.89-1.13), and for GG carriers, it was RR 1.21 (95%CI, 1.06-1.40). We identified evidence of heterogeneity (P=0.004) and a trend (P=0.0009) across genotypic groups.\n\nConclusionsIn contrast to the interpretation provided by authors of the analysis based in the ACCELERATE trial, the available evidence lends weak support to a potential interaction of CETP treatment by ADCY9 genotype on risk of major adverse cardiac events. Additional data, e.g. from the ongoing dal-GenE trial focused explicitly on this interaction, should provide further clarity regarding the robustness of this pharmacogenetic effect.