SO056THE CLINICAL AND IMMUNOLOGICAL IMPACT OF LOW DOSE RITUXIMAB IN CLINICAL NEPHROLOGY

Abstract Background and Aims Currently, the dose of rituximab used in nephrology practice is mostly extrapolated from the dose used in lymphoproliferative disorders. It is possible that a lesser dose may suffice when treating a non-neoplastic disorder. We conducted this study to study the clinical response and CD19 B cell suppression with a single dose of 100mg rituximab in nephrology practice Method This was a single center prospective study of role of 100mg rituximab as initial dose in steroid dependent (SDNS), frequently relapsing nephrotic syndrome (FRNS), idiopathic membranous nephropathy (MN) and high immunologic risk kidney transplantation with subsequent doses based on CD19 B cell reconstitution. Results Following 100mg rituximab in 42 patients, CD19 B cell percentage decreased from 16.3+7.6 to 0.3±0.3, 1.9±1.7 and 4.0±4.5 by 30, 90 and 180 days respectively. At 30th day, 40(95.2%) had CD19 B cell count <1%. Of the 30 patients with SDNS and FRNS followed up for one year, 29(96.7%) went into remission at day 30. Remission was sustained in 23(76.6%) at day 180 and 21(70%) at 1 year. There was significant decrease [P <0.001] in the dose of steroids needed to maintain remission at 180 days following rituximab (0.27±0.02mg/Kg to 0.02±0.00mg/Kg). Of the five patients with MN, four patients achieved remission by 6 months. Remission was sustained in three patients by 1 year. Of the 7 kidney transplant recipients, 2 had antibody mediated rejections though CD19 B cells were suppressed even at one year. Conclusion Low dose of 100 mg rituximab is sufficient to deplete CD19 B cells for up to 90days and is effective in inducing remission in SDNS and FRNS and MN. Targeting subsequent doses depending on CD19 B cell reconstitution may prevent relapses, limit toxicity and be cost effective.