The safety of calcineurin inhibitors for kidney-transplant patients

Introduction: Cyclosporine-A and tacrolimus are the cornerstones in modern immunosuppression after organ transplantation. They are potent inhibitors of calcineurin, that is, so-called calcineurin-inhibitors (CNIs). However, because these drugs have narrow therapeutic windows, they are associated with many side-effects, with some being dose related. Areas covered: The most frequent side-effect of CNIs is nephrotoxicity, which in the long term can contribute, to allograft deterioration. Other frequent side-effects include metabolic disorders (new onset of diabetes, dyslipidemia), neurotoxicity, or promoting of de novo cancers. Expert opinion: In kidney transplantation, many strategies have been developed to minimize nephrotoxicity while maintaining efficacy of immunosuppression: for example, the minimization of CNI in addition to either full-dose mycophenolic acid or low doses of m-TOR inhibitors, mainly everolimus (EVR). Attempts made to eliminate CNIs by replacing them with m-TOR inhibitors have been unsuccessful because of occurrence of de novo donor-specific alloantibodies in a substantial number of patients, associated with antibody-mediated rejection. Conversely, CNI-avoidance by replacing them by Belatacept is feasible with very good renal function in the long term despite a significant increase in acute cellular rejections within the first-year posttransplantation. Other side-effects of CNIs, such as neurologic disorders, diabetes, dyslipidemia, viral infections, and cancer, seem to be less frequent in low-dose or CNI-free immunosuppressive regimens. Thus, although CNIs remain the major immunosuppressive treatment, their dosage should be minimized by using them with either full-dose MPA or reduced-dose EVR.