Early cyclosporine a withdrawal in kidney transplant recipients under a sirolimus-based immunosuppressive regimen: pathological study of graft biopsies at 1-year posttransplant

Clinical application of sirolimus in renal transplantation: an update

In addition to an analysis of the final results of phase I/II and phase III clinical trials of sirolimus (SRL), this review focuses on the recent results of several studies in renal transplantation, which include diverse combinations of SRL with other immunosuppressive agents. While SRL was initially introduced as an adjunctive agent to calcineurin inhibitors, it is now serving as the base for therapies that spare or avoid these nephrotoxic drugs. However, to optimize the use of SRL as base therapy, further work is necessary to determine target concentrations, requirement for concomitant steroids and/or nucleoside synthesis blockers, and countermeasure therapy to overcome the drug's adverse effects.

Early Cyclosporine A Withdrawal in Kidney-Transplant Recipients Receiving Sirolimus Prevents Progression of Chronic Pathologic Allograft Lesions

BACKGROUND

Nephrotoxicity of calcineurin inhibitors (CNIs) is partially responsible for the development of chronic allograft nephropathy (CAN). Sirolimus has demonstrated its potential to substitute for CNIs because it lacks significant nephrotoxicity and shows a short-term immunosuppressive capacity comparable with that of cyclosporine. This results in the maintenance of better renal function when cyclosporine is eliminated, but it has not been demonstrated whether this benefit is associated with an improvement in the pathologic substrate and a reduction in CAN.

METHODS

We analyzed pretransplant and 1-year renal-allograft biopsies from 64 patients enrolled in a multicenter trial. Patients received cyclosporine and sirolimus during the first 3 months after transplant and were then randomly assigned to continue with cyclosporine or have it withdrawn. Histologic chronic allograft lesions were compared between groups.

RESULTS

The percentage of patients in whom chronic pathologic lesions progressed was lower in the group of cyclosporine elimination. Significant differences were observed in chronic interstitial and tubular lesions (70% vs. 40.9% [P<0.05] and 70% vs. 47.8% [P<0.05], respectively), whereas no differences were observed in acute lesions (subclinical rejection). Prevalence of CAN at 1 year was lower in this group, as was the severity and incidence of new cases (P<0.05).

CONCLUSIONS

Early cyclosporine withdrawal associated with sirolimus administration is followed by an improvement in renal function, a reduction in the progression of chronic pathologic allograft lesions, and a lower incidence of new cases and severity of CAN during the first year after transplantation. This benefit may result in better long-term graft outcome.

Early elimination of cyclosporine in kidney transplant recipients receiving sirolimus prevents progression of chronic pathologic allograft lesions

Cyclosporine elimination in a regimen including sirolimus has been shown to be a safe and effective approach to improve graft function. Nevertheless, it is still unknown whether the functional benefit of CyA withdrawal coincides with a subsequent reduction in histologic lesions of chronic damage or development of chronic allograft nephropathy. This consideration would forecast a reduction in the rate of long-term graft loss. We analyzed 114 graft biopsies from a subgroup of 57 patients that had been included in a randomized study to eliminate CyA at 3 months posttransplant from a regimen including sirolimus either in group A CyA + SRL vs group B of SRL with CyA elimination at 3 months. Every patient had two biopsies, one at transplantation and another at 1 year. The biopsy reading was performed in a blinded manner by a central pathologist using the Banff 1997 and the CADI classifications. A significantly lower rate of progression of tubular and interstitial chronic lesions between basal and 1-year biopsies was observed for group B patients. In addition, the incidence of new cases of chronic allograft nephropathy during the first year was significantly lower in the group in which CyA had been eliminated at 3 months posttransplant. We conclude that early elimination of CyA in the first months posttransplant, when SRL is used as the main immunosuppressant, reduces the appearance or worsening of chronic histologic lesions, probably as a consequence of long-term CyA toxicity prevention.