Conversion from Calcineurin Inhibitors to mTOR Inhibitors in Renal Transplantation: A Single Centre Experience

OBJECTIVE : Mammalian target of rapamycin (mTOR) inhibitors are among the immunosuppressive drugs used in renal transplantation. The aim of this study was to reveal our experiences in conversion from calcineurin inhibitors (CNI) to mTOR inhibitors in 20 renal transplant patients. MATERIAL and METHODS : Various protocols were used in the conversion from CNIs to mTOR inhibitors. CNIs were discontinued and mTOR inhibitors were initiated in patients with malignancy. In cases of CNI toxicity and in cases in which conversion was performed for other causes, reduced doses of CNIs were administered for three days in combination with mTOR inhibitors. RESULTS: The study included 20 renal transplant patients, of whom 14 were male and 6 were female. The mean age of the patients was 43.5 +/- 8.8 years. The reason for conversion was CNI toxicity in 16 patients (80%), malignancy in 3 patients (15%), and premalignant lesion in 1 patient (5%). Conversion to mTOR inhibitors [(sirolimus (n=14) and everolimus (n=6)] was performed at 62.6 +/- 45.7 months after transplantation. The mean follow-up period after administration of mTOR inhibitors was 50.5 +/- 29.9 months. The mean proteinuria at the time of conversion was 227.5 +/- 147.9 mgr/day and increased to 636.5 +/- 388.2 mgr/day after treatment with mTOR inhibitors (p<0.001). There was an increase in the creatinine levels after treatment with mTOR inhibitors, though it was not significant (p=0.126). Everolimus was not discontinued in any patient, but sirolimus had to be discontinued in three patients that was due to proteinuria in two patients and pneumonia in one patient. CONCLUSION: Conversion from CNIs to mTOR inhibitors may cause side-effects. When basal renal functions are good and when proteinuria is mild, conversion may result in fewer side effects.