The CYP3A5 and ABCB1 Gene Polymorphisms in Kidney Transplant Patients and Establishment of Initial Daily Tacrolimus Dosing Formula.

BACKGROUND: Tacrolimus is an immunosuppressive drug used to prevent organ rejections. Many factors could influence blood concentration of tacrolimus. OBJECTIVE: To detect genotypes of cytochrome P450 3A5 (CYP3A5) and ABCB1 in kidney transplant patients and establish initial daily tacrolimus dosing formula based on genotypes of CYP3A5 and ABCB1 and patients' clinical parameters. METHODS: Sequence specific primer polymerase chain reaction (PCR) and PCR restriction fragment length polymorphism were used to detect genotypes of CYP3A5 and ABCB1. The blood cell, procalcitonin, C-reactive protein, height, weight, age, gender and other clinical parameters were recorded. Multiple linear regression analysis and Pearson correlation analysis were used to conduct date analysis. RESULTS: 102 cases were enrolled in cohort 1, and there were 10 cases of CYP3A5 *1/*1 (9.8%), 28 cases of CYP3A5 *1/*3 (27.5%), and 64 cases of CYP3A5 *3/*3 (62.7%). The distributions of ABCB1 C3435T genotype were CC 36 (35.3%), CT 52 (51.0%), and TT 14 (13.7%). The distributions of ABCB1 G2677T/A genotype were GG 39 (38.2%), GT 40 (39.2%), and TT 23 (22.5%). The formula was 7.499 + (0.053 × Weight) - (0.029 × Hemoglobin concentration) - (1.045 × CYP3A5 genotype) (CYP3A5 genotype: *1/*1 type inputs 0, *1/*3 type inputs 1, *3/*3 type inputs 2). The predicted doses from the established formula had a significant correlation (r = 0.605) with actual clinical doses (P < 0.05). CONCLUSION AND RELEVANCE: Hemoglobin concentration, weight, and CYP3A5 genotype should be considered using tacrolimus. The initial daily tacrolimus dosing formula established can make a good prediction.