TACrolimus in Renal Transplantation: Individualization by Pharmacogenetic

Renal transplantation is the treatment of choice of the chronic renal insufficiency arrived at its final stage. Tacrolimus is an immunosuppressant treatment used for the prevention of episodes of acute rejection. Tacrolimus is characterized by a narrow therapeutic index and important interindividual variations of its pharmacokinetic characteristics. Proteins CYP3A4 and CYP3A5 are responsible of intestinal and hepatic metabolism of Tacrolimus. Various polymorphisms for CYP3A5 and CYP3A4 were described and several retrospective studies suggested an association between a genetic polymorphism of CYP3A5 and the pharmacokinetic parameters of Tacrolimus. In particular, we showed that the presence of an allele CYP3A5\*1 was associated to the use of more important amounts of Tacrolimus to obtain the desired blood concentrations. This study is a national, multicentric, prospective, opened, randomized on two arms of treatment. 280 receivers of a renal transplant in 12 centres will be included. The genotyping of gene CYP3A5 will be carried out in the 6 days following transplantation. During the first week, the patients will be treated by basiliximab, MMF and corticosteroids. They will be randomized (central randomization) in D6 to receive either Tacrolimus at 0.2 mg/kg/d, or at a dosage adapted to their genotype. After determination of the first residual blood concentration of Tacrolimus realized after six oral intakes, the daily amounts of Tacrolimus could be modified if necessary to reach the desired blood concentrations. The total duration of the study for a patient is 3 months after transplantation. The objective of this study is to evaluate the impact of the adaptation, according to the genotype of the CYP3A5 of the patient, of the first amount of Tacrolimus on the first residual blood concentration of Tacrolimus, keeping in mind the aim of the individualization of dosage schedule by pharmacogenetic approach. Principal criterion : Comparison, between the two groups, of