Conversion to Mycophenolate Mofetil From Azathioprine Shows Significant Positive Effect on Graft Function in Long-Term Past–Kidney Transplantation Stable-State Patients

ObjectivesA number of reports have shown that the efficacy of mycophenolate mofetil (MMF) is superior to that of azathioprine (AZP) for long-term kidney allograft survival. We conducted a retrospective single-center study to evaluate renal function more than 2 years after conversion from AZP to MMF in kidney transplant recipients several years after transplantation.MethodsAZP was converted to MMF in 51 recipients at 17.0 ± 0.8 years after kidney transplantation who were followed up for more than 2 years after conversion. Estimated glomerular filtration rate (eGFR) was determined using the Formula of the Japanese Society of Nephrology.ResultsThe eGFR was significantly greater at 1 year before conversion (41.72 ± 1.91 mL/min/1.73 m2) as compared with the day of conversion (39.04 ± 1.82 mL/min/1.73 m2; P < .05). After conversion, eGFR plateaued to 39.30 ± 2.01 mL/min/1.73 m2 at 1 year and 38.24 ± 2.42 mL/min/1.73 m2 at 2 years after conversion. The average eGFR slopes were −2.96 ± 0.36 mL/min/1.73 m2 per year for AZP and 1.22 ± 0.10 mL/min/1.73 m2 per year for MMF (P < .0001). Cyclosporine (CSA) was reduced from 176 ± 9.3 to 165 ± 9.8 mg/d (P = .0394) after the switch, whereas the CSA trough level was increased from 77.3 ± 6.6 to 118 ± 9.8 ng/mL (P = .0017). Furthermore, the daily dose of tacrolimus (TAC) was decreased from 3.5 ± 0.3 to 3.1 ± 0.3 mg/d (P = .0083).ConclusionsOur findings demonstrated the safety of conversion from AZP to MMF even in the patients who underwent renal transplantation several years prior. In addition, these short-term results indicated the improvement in allograft function following conversion.