Kai Ming Chow, Cheuk Chun Szeto, Fernand Mac-Moune Lai, Cathy Choi-Wan Luk, Bonnie Ching-Ha Kwan, Chi Bon Leung, Philip Kam-Tao Li

We tested the strategy of mTOR inhibitors with calcineurin inhibitor minimization in renal transplant recipients with known chronic allograft dysfunction. In this open-label, single-arm study, renal transplant patients were recruited after biopsy-confirmed chronic allograft dysfunction in the absence of acute rejection episode within 2 months, with proteinuria <0.8 g/day, and serum creatinine <220 μmol/L or estimated glomerular filtration rate >40 mL/min/1.73 m(2). They were converted to everolimus (aiming for trough everolimus level 3-8 ng/mL) with cyclosporine minimization, to assess the effect on renal function, rate of glomerular filtration rate decline, and longitudinal transplant biopsy at 12 months. Seventeen Chinese patients (median transplant duration, 4.2 years) were recruited; no patients discontinued study medication. The mean slope of the glomerular filtration rate over time was -4.31±6.65 mL/min/1.73 m(2) per year in the year before everolimus, as compared with 1.29±5.84 mL/min/1.73 m(2) per year in the 12 months of everolimus therapy, a difference of 5.61 mL/min/1.73 m(2) per year (95% confidence interval [CI], 0.40-10.8) favoring everolimus therapy (P=0.036). Serial renal biopsy histology showed significant decrease of tubular atrophy (15.7%±11.3% versus 7.1%±7.3%, P=0.005) and interstitial fibrosis (14.8%±11.5% versus 7.2%±8.2%, P=0.013). Intrarenal expression of TGF-β1 mRNA showed a nonsignificant decrease after everolimus treatment. In renal transplant recipients with biopsy-confirmed chronic allograft dysfunction, we found a significant beneficial effect of everolimus rescue therapy and calcineurin inhibitor minimization strategy on the improvement of glomerular filtration rate decline rate. In secondary analysis, everolimus was shown to slow down the disease progression by reducing the tubular atrophy and interstitial fibrosis scoring.