Rituximab, Use and B Cell Depletion in Patients with Membranous Nephropathy- A Retrospective, Observational Study.

INTRODUCTION: Rituximab (Rtx), an anti-CD20 monoclonal antibody, results in selective B-cell depletion and has emerged as an important therapeutic option in idiopathic membranous nephropathy (MN). We conducted a retrospective observational study to evaluate the efficacy and tolerability of Rtx in MN with respect to the B-cell count depletion.

METHODS: Twenty patients with biopsy proven primary MN, both treatment naïve and treatment resistant, who received a fixed dose protocol of 500mg IV Rtx 1month apart were retrospectively observed with a minimum follow-up period of 12 months. The primary clinical outcome was complete (CR) or partial remission (PR) at 12 months in relation to B-cell depletion at 6 and 12 months.

RESULTS: All were patients (men, 90%) of PLA2R-Ab positive with MN with a mean age of 37.7 ± 12.5 years. The mean 24-h urinary protein was 7.5 ± 2.15 gm/day, serum albumin was 2.01 ± 0.6gm/dL, and eGFR was 86.5 ± 20 mL/min/1.73m2 . Primary composite outcome at 12 months was 66.7%, with 5.6% CR and 61.1% PR.The mean PLA2R-Ab at 12 months was low in those with remission compared to those who did not achieve (17.8 ± 21.2 RU/mL vs 311.7 ± 356.0; P = 0.01). Sustained B cell depletion at 6 months was seen in 84.3% (OR = 2.2, 95% CI = 0.11-42.7; P = 0.53) and 32% at 12 months (OR = 2.25, 95% CI = 0.18-27.7, and P = 0.66).

CONCLUSION: Acceptable remission rates were seen with Rtx in both treatment naïve and treatment-resistant patients with MN. There was no significant association between B-cell depletion and remission.