A Low Fixed Tacrolimus Starting Dose Is Effective and Safe in Chinese Renal Transplantation Recipients

Functional CYP3A variants affecting tacrolimus trough blood concentrations in Chinese renal transplant recipients

The aim of this study was to identify novel genetic variants affecting tacrolimus trough blood concentrations. We analyzed the association between 58 single nucleotide polymorphisms (SNPs) across the CYP3A gene cluster and the log-transformed tacrolimus concentration/dose ratio (log (C₀/D)) in 819 renal transplant recipients (Discovery cohort). Multivariate linear regression was used to test for associations between tacrolimus log (C₀/D) and clinical factors. Luciferase reporter gene assays were used to evaluate the functions of select SNPs. Associations of putative functional SNPs with log (C₀/D) were further tested in 631 renal transplant recipients (Replication cohort). Nine SNPs were significantly associated with tacrolimus log (C₀/D) after adjustment for CYP3A5*3 and clinical factors. Dual luciferase reporter assays indicated that the rs4646450 G allele and rs3823812 T allele were significantly associated with increased normalized luciferase activity ratios (p < 0.01). Moreover, CYP3A7*2 was associated with higher TAC log(C₀/D) in the group of CYP3A5 expressers. Age, serum creatinine and hematocrit were significantly associated with tacrolimus log (C₀/D). CYP3A7*2, rs4646450, and rs3823812 are proposed as functional SNPs affecting tacrolimus trough blood concentrations in Chinese renal transplant recipients. Clinical factors also significantly affect tacrolimus metabolism.

Effects of CYP3A5 Polymorphisms on Efficacy and Safety of Tacrolimus Therapy in Patients with Idiopathic Membranous Nephropathy

Background

Tacrolimus (TAC) is beneficial for patients with idiopathic membranous nephropathy (IMN). It has a narrow therapeutic concentration range and many factors influence TAC blood concentration. CYP3A5 is the most important enzyme in TAC metabolism. The aim of this study was to analyze the effects of CYP3A5 gene polymorphisms on the efficacy and safety of TAC in IMN patients.

Patients and Methods

Patients with IMN who received oral TAC (0.05-0.075mg/kg/day) combined with prednisone (0.5mg/kg/day) from March 2016 to October 2018 were included. The data of clinical characteristics, therapeutic drugs and adverse reactions of patients were collected at baseline and during 24 weeks of treatment. Patients were divided into two groups according to different CYP3A5 genetic polymorphisms. The significant differences in the efficacy and side effects between the two groups were analyzed.

Results

A total of 76 patients who completed follow-up were divided into CYP3A5 nonexpresser (CYP3A5*3/*3) group and CYP3A5 expresser (CYP3A5 *1/*3) group. The significant association between the CYP3A5 phenotype and TAC metabolism was observed. A total of 43 case-times patients exhibited adverse effects. The infection rate in CYP3A5 nonexpresser group (21.95%) was remarkably higher than the rate in CYP3A5 expresser group (5.71%). Blood concentration and C₀/D levels were risk factors for adverse events through logistic regression analysis. There was no statistical difference between the study groups with respect to the efficacy.

Conclusion

Our results demonstrated that CYP3A5 polymorphisms had important guiding roles in the treatment of IMN with tacrolimus. CYP3A5 expressers required higher daily doses of TAC to achieve the target drug concentration, but with fewer side effects. CYP3A5 genetic polymorphism might be used for TAC dosing adjustment to optimize the treatment for patients with IMN.

Non-linear Relationship between Tacrolimus Blood Concentration and Acute Rejection After Kidney Transplantation: A Systematic Review and Dose-Response Meta-Analysis of Cohort Studies

BACKGROUND

Maintaining the exposure of tacrolimus (Tac) after kidney transplantation (KT) must be necessary to prevent acute rejection (AR) and improve graft survival，but there is still no clear consensus on the optimal Tac target blood concentration and concentration-effect relationship is poorly defined.

METHODS

We conducted a dose-response meta-analysis to quantitatively assess the association between Tac blood concentration and (AR) or adverse effects after KT. A comprehensive search of PubMed, Embase and Cochrane library databases was conducted to find eligible studies up to 10th September 2018. Unpublished data from patients receiving KT in West China Hospital (Sichuan University, China) were also collected. Both twostage dose-response and one-stage dose-response meta-analysis models were used to improve the statistical power.

RESULTS

A total of 4967 individuals from 10 original studies and 1453 individuals from West China Hospital were eligible for the ultimate analysis. In the two-stage dose-response meta-analysis model, we observed a significant non-linear relationship between Tac blood concentration and AR (P < 0.001) with moderate heterogeneity (I2 = 46.0%, P = 0.08). Tac blood concentration at 8ng/ml was associated with the lowest risk of AR (RR: 0.26, 95%CI: 0.13 - 0.54) by reference to 2ng/ml. Tac concentration at 7.0 - 11.0 ng/ml reduced the risk of AR by at least 70%, 5-14 ng/ml by at least 60%, and 4.5 - 14 ng/ml at least 50%. In the one-stage dose-response model, we also found a strong non-linear relationship between Tac and AR (P < 0.001) with moderate heterogeneity (I2 = 41.2%, P = 0.10). Tac concentration of 7.5 ng/ml was associated with the lowest risk of AR (RR: 0.35, 95%CI: 0.16 - 0.77). The blood concentration at 5.5 - 9.5 ng/ml was associated with the reduced AR by at least 60% and 4.5 - 10.5 ng/ml by at least 50% by reference to 2 ng/ml.

CONCLUSION

Maintaining Tac blood concentration at 5 - 9.5 ng/ml within the first year may prevent AR most effectively.