Mycophenolate mofetil therapy in immunoglobulin A nephropathy: histological changes after treatment

Background: Endocapillary hypercellularity independently predicts renal outcome in immunoglobulin A nephropathy (IgAN). Mycophenolate mofetil (MMF) treatment is offered to patients presenting to the Imperial College Renal and Transplant Centre with IgAN and histological evidence of endocapillary hypercellularity. Clinical trials of MMF in IgAN have been inconclusive and have been limited by a lack of specific histological inclusion and exclusion criteria when recruiting patients. Evidence of histological improvement following MMF treatment would support its therapeutic use. We therefore reviewed histological changes after MMF therapy in a cohort of IgAN patients. Method: Eighteen IgAN patients with native renal biopsies before and after repeated MMF treatment were identified. Patients were excluded if they had received any other immunosuppressive therapy, including corticosteroids. On the basis of the Oxford Classification of IgAN, we reviewed histological changes after MMF treatment. Results: Nine patients (50%) were male. At diagnostic renal biopsy, the median age was 35 years [interquartile range (IQR) 30-41], serum creatinine was 97 µmol/L (IQR 79-153) and urine protein creatinine ratio (UPCR) was 146 mg/mmol (IQR 98-212). The median time between biopsies was 24 months (range 9-41). Following MMF treatment, repeat biopsy demonstrated statistically significant improvement in the mean percentage of glomeruli showing endocapillary hypercellularity and cellular/fibrocellular crescents. There was no change in mesangial hypercellularity, segmental sclerosis or tubular atrophy scores. Mesangial IgA deposition was also significantly reduced. Histopathological improvement persisted after the cessation of MMF therapy, suggesting that 2 years of treatment is adequate for benefit. The median serum creatinine remained stable at 3 years follow-up at 104 µmol/L (IQR 79-147). Conclusion: MMF treatment is associated with histopathological improvement in IgAN.