Calcineurin inhibitor-free protocols: risks and benefits.

The nephrotoxic and extra-renal adverse effects associated with calcineurin inhibitor (CNI) therapies appear to have a negative impact on long-term graft survival. Several CNI minimization protocols have been recently studied. These protocols involve either early CNI avoidance or CNI withdrawal. CNI withdrawal strategies are associated with a significant improvement in renal function and graft survival on both a short and long-term basis. Delayed and progressive withdrawal appears to be safer. Maintaining a high mycophenolate mofetil (MMF) or sirolimus (SIR) exposure minimizes the risk of acute rejection. CNI avoidance regimens using maintenance mono-therapy or combination therapies without induction appear to be immunologically risky and unsafe. In contrast, the combination of SIR + MMF with induction therapy reduces markedly the incidence of acute rejection and chronic allograft nephropathy (CAN). Two year patient and graft survival levels were comparable. CAN as well as the incidence and the risk for cancer in addition to blood pressure profiles and uric acid levels were overall lower in the SIR-based treatment. In contrast, hyperlipidemia, delayed wound healing, lymphocele, arthralgias, thrombocytopenia and study protocol deviations were reported more frequently in the SIR-maintenance protocols. Longer-term follow-ups are definitely needed to determine whether these avoidance strategies will result in a significant improvement in long-term patient and graft survival. Outcome differences among various protocols within the same CNI elimination strategy are probably related to study design, patient selection criteria, immunosuppression monitoring methods, indications for graft biopsies, environmental, and both genetic and ethnic factors. All monitoring techniques are unreliable short of a graft biopsy. Preliminary results on drug lymphocyte binding may offer new guidelines for tailoring immunosuppression. Whether these protocols based on SIR or SIR + MMF can also be extended to high risk patients is currently unknown. These encouraging results allow speculation but with caution that the use of the combination of non-nephrotoxic immunosuppression such as SIR and MMF, might change dramatically the natural course of CAN and may influence long-term patient survival.