Retrospective single-arm cohort study of steroid-dependent minimal change nephrotic syndrome treated with very low-dose rituximab.

ABSTRACT

AIM: Conclusions regarding the best rituximab (RTX) dose to maintain remission and reduce immunosuppressant dependence in adult patients with steroid-dependent minimal change nephrotic syndrome (MCNS) are inconsistent. We report the first low-dose (< 375 mg/m2 BSA) RTX therapy, administered once every 6 months. MATERIALS AND METHODS: In this retrospective single-arm cohort study, we investigated the safety and efficacy of low-dose RTX therapy to reduce and ultimately stop prednisolone (PSL) and cyclosporine (CyA) treatment. 13 patients (8 men and 5 women; aged 16 - 65 years; 8-year median treatment history; 12 patients concurrently taking CyA) with steroid-dependent MCNS were chosen to maintain remission following low-dose RTX (200 mg/body) administration. RESULTS: The median period of subject observation following the first RTX dosing was 34 months (cumulative RTX dose 400 - 1,400 mg). RTX significantly reduced PSL and CyA doses during the final observation in each subject (median dose PSL 15→0 mg/day, p = 0.0002; CyA 80→0 mg/day, p = 0.0005). All patients maintained complete remission after discontinuing both drugs for a median complete remission (CR) maintenance period of 25 months. One patient showed relapse following the first RTX dose, but a temporary increase in PSL and CyA dose restored the remission. No serious RTX-related adverse effects were observed. Even with MCNS remission, peripheral CD19-positive cell count was not depleted in 90.5% of all cases. CONCLUSION: Low-dose RTX therapy appears to be effective in maintaining remission and reducing immunosuppressant doses in patients with steroid-dependent MCNS, which might involve a B-cell-independent mechanism.