Lower tacrolimus daily dose requirements and acute rejection rates in the CYP3A5 nonexpressers than expressers.

Background: CYP3A5 genetic polymorphisms contribute to marked interindividual differences in the metabolism of and response to tacrolimus in humans.

Objective: This study was aimed to clarify the impact of the CYP3A5*3 variant on tacrolimus dose requirements and acute rejection rates in patients with organ transplantation.

Methods: A literature search was performed up to August 2009 by using the Cochrane library, PubMed, Medline, and EMBase.

Results: Twenty-three studies (a total of 1779 patients) were included in this meta-analysis. Eighteen studies (1443 patients) were involved in renal transplantation and five studies (336 patients) in liver transplantation. Results of meta-analysis demonstrated that, in renal transplant patients, despite the presence of significant heterogeneity, CYP3A5 expressers required higher mean tacrolimus daily doses by 0.045 mg/kg (95% confidence interval (CI), 0.033-0.056) than nonexpressers. Furthermore, sub-analysis of the time of posttransplantation showed that CYP3A5 expressers required higher daily doses than nonexpressers by 0.010, 0.084, 0.041, 0.037, and 0.044 mg/kg at week 2, and at month 1, 3, 6, and 12, respectively. Subset analysis of the ethnicity of organ recipients indicated that mean tacrolimus daily doses were 0.056, 0.037, and 0.077 mg/kg higher in CYP3A5 expressers than non- expressers for white, Chinese, and Japanese patients, respectively. In contrast, for liver transplant patients, higher tacrolimus daily doses were required not only in CYP3A5 expressers of the organ donors than nonexpressers by 0.024 mg/kg (95% CI, 0.019-0.028), but also in CYP3A5 expresser of the organ recipients than nonexpresser by 0.012 mg/kg (95% CI, 0.005-0.018). However, a significant difference in the acute organ rejection rate was observed only at one month (odds ratio, 3.27; 95% CI, 1.57-6.81; P=0.002).

Conclusion: Tacrolimus daily dose requirements may vary with the presence of the CYP3A5*3 variant, ethnicity of the organ recipients, and the time of posttransplantation. In addition, the acute organ rejection rate may be higher in CYP3A5 expressers than nonexpressers over the first month after transplantation.