Influence of CYP3A5 and ABCB1 gene polymorphisms on calcineurin inhibitor‐related neurotoxicity after hematopoietic stem cell transplantation

Yanagimachi M, Naruto T, Tanoshima R, Kato H, Yokosuka T, Kajiwara R, Fujii H, Tanaka F, Goto H, Yagihashi T, Kosaki K, Yokota S. Influence of CYP3A5 and ABCB1 gene polymorphisms on calcineurin inhibitor‐related neurotoxicity after hematopoietic stem cell transplantation.
Clin Transplant 2010: 24: 855–861. © 2009 John Wiley & Sons A/S. Abstract: Background: One severe side effect of calcineurin inhibitors (CNIs: such as cyclosporine [CsA] and tacrolimus [FK506]) is neurotoxicity. CNIs are substrates for CYP3A5 and P‐glycoprotein (P‐gp), encoded by ABCB1 gene. In the present study, we hypothesized that genetic variability in CYP3A5 and ABCB1 genes may be associated with CNI‐related neurotoxicity. Methods: The effects of the polymorphisms, such as CYP3A5 A6986G, ABCB1 C1236T, G2677T/A, and C3435T, associated with CNI‐related neurotoxicity were evaluated in 63 patients with hematopoietic stem cell transplantation. Results: Of the 63 cases, 15 cases developed CNI‐related neurotoxicity. In the CsA patient group (n = 30), age (p = 0.008), hypertension (p = 0.017), renal dysfunction (p < 0.001), ABCB1 C1236T (p < 0.001), and G2677T/A (p = 0.014) were associated with neurotoxicities. The CC genotype at ABCB1 C1236T was associated with it, but not significantly so (p = 0.07), adjusted for age, hypertension, and renal dysfunction. In the FK506 patient group (n = 33), CYP3A5 A6986G (p < 0.001), and ABCB1 C1236T (p = 0.002) were associated with neurotoxicity. At least one A allele at CYP3A5 A6986G (expressor genotype) was strongly associated with it according to logistic regression analysis (p = 0.01; OR, 8.5; 95% CI, 1.4–51.4). Conclusion: The polymorphisms in CYP3A5 and ABCB1 genes were associated with CNI‐related neurotoxicity. This outcome is probably because of CYP3A5 or P‐gp functions or metabolites of CNIs.