Effect of vitamin D receptor genetic polymorphism on the clinical response to angiotensin converting enzyme inhibitors therapy among breast cancer patients with chemotherapy induced cardiomyopathy

Abstract

Abstract Background Blockade of the renin-angiotensin-aldosterone system (RAAS) is the cornerstone treatment of chemotherapy induced cardiomyopathy (CIC) yet, variability in response to angiotensin converting enzyme inhibitors (ACEIs) acting on the RAAS is well-documented. Vitamin D was found to play a role in regulating RAAS. Previous studies revealed an inverse relationship between levels of vitamin D in serum and RAAS activation. Purpose The current study is primarily to evaluate the association between genetic variants in the vitamin D receptor (VDR) and clinical response to ACEIs among breast cancer patients receiving chemotherapy with CIC. Methods A total of 60 breast cancer patients with CIC (mean ejection fraction 30%) on β-blocker therapy were started on a ACEIs and followed for 6 months. Post-ACEIs-treatment changes in ejection fraction (EF) and serum potassium (K) were evaluated. We genotyped VDR gene polymorphisms including; ApaI (rs7975232), TaqI (rs731236), BsmI (rs1544410) and FokI (rs2228570) variants using TaqMan technique. Stepwise linear regression was performed to identify genetic and clinical factors associated with variability in ACEIs response, with adjustment for all potential confounding covariates. Results BsmI (rs1544410) (CT) heterozygous and TaqI (rs731236) (GA) genotypes had a significant increase in EF (12.8% and 10.8 %, respectively) and serum K (1.1 mEq/L and 0.91 mEq/L respectively); adjusted-p = 0.0001 and 0.004 for ∆EF and adjusted-p = 0.005 and 0.002 for ∆K. In contrast, (AA) homozygous carriers of the ApaI SNP (rs7975232) had a smaller increase in EF (∆EF = 1.2%) and K (∆K = 0.1 mEq/L) compared to (CA) (∆EF = 6.5%, ∆K = 0.73mEq/L) and (CC) (∆EF = 9%, ∆K = 0.9mEq/L) carriers; adjusted-p = 0.003 for ∆EF, adjusted-p = 0.004 for ∆K. Finally, for the FokI SNP (rs2228570), there was no significant change in EF and serum K level. Conclusion The results from this study highlight that BsmI (rs1544410) and TaqI (rs731236) are strong predictors of response to ACEIs therapy in chemotherapy-induced cardiomyopathy (CIC).