Interest of Calcineurin Activity for the Therapeutic Tacrolimus Monitoring in Renal Recipients

Some authors showed that the determination of calcineurin (enzyme of cyclosporin and tacrolimus action) activity was very interesting in bone narrow and hepatic transplant in order to monitor tacrolimus or cyclosporin. Indeed, Furthermore, target Tac concentrations still fail to provide in certain patients an appropriate immunosuppression reflected by rejection. Because a lack of data in renal transplant, we propose to study this population treated by tacrolimus, mycophenolate mofetil and corticoids in the first three months following the transplantation.

Our major aim is to study the relationship between calcineurin activity and immunologic events in 200 renal recipients treated with tacrolimus in the first three months following transplant. Immunologic events could be acute rejections and infraclinical rejections. The second aims are 1) if this relationship exists, to define the threshold predicting acute rejection using ROC-curve, 2) to define variations between pharmacodynamic (calcineurin activity) and pharmacokinetic (whole blood concentrations) tacrolimus monitoring and 3) to compare calcineurin activity in patients with acute rejection and those with borderline rejection. Blood samples will be collected into EDTA-containing vacutainers prior to the tacrolimus morning administration and at 2, 4, 6 and 9 hours following the administration at D7, D14 and D21. Whole blood tacrolimus concentrations and calcineurin activity were measured using LCMSMS and HPLC techniques. After D21, only residual measurements will be carried out at D28, M2 and M3. A comparative statistical analysis will be performed between data defined with and without rejection. In case of difference, a ROC curve analysis could define normal ranges of calcineurin activity.

This is the second study of the Sud FRANCILIEN Institute for Research in Nephrology-Transplantation defined with Nephrology departments in Mondor and BICETRE hospitals and the object "Interest of pharmacodynamics of immunosuppressive drugs in renal-transplant recipients" is a new theme of these teams.