#4709 PERSONALISED INDUCTION THERAPY IN ANCA GLOMERULONEPHRITIS

Abstract Background and Aims Patient and kidney outcome in ANCA glomerulonephritis (GN) remains unsatisfactory. Rituximab use failed to reduce the rate of infectious complications and demonstrates a significant rate of hypogammaglobulinaemia in ANCA vasculitis. Adjusting the rituximab dosage to the individual patient's need promises a reduction in treatment toxicity. Method Retrospective analysis of a single centre cohort of ANCA GN patients with disease flares between 2019 – 2022 using a stratified induction immunosuppression with rituximab and cyclophosphamide. Treatment intensity was adjusted to resolution of systemic inflammation and microscopic haematuria, peripheral CD19 cell count depletion and immunoglobulin G (IgG) levels. Results 45 patients (median age 57 years, 55.7% female, median eGFR 27 mls/min) were treated with a median dose of 1.5 grams Rituximab during induction (interquartile range, IQR 1 – 2 grams). 18 patients received concomitant intravenous cyclophosphamide pulses to control the acute inflammation (median cumulative dose of 2 grams, IQR 1.65 – 3 grams). Peripheral B cell depletion was 91.4% at 3 months and 90.3% at 6 months (<3 CD19 cells/ul). During the initial 12 months treatment, IgG level fell below 7g/l in 20 patients, below 5g/l in nine patients and below 3g/l in one patient. Seven patients required renal replacement therapy at diagnosis (15.6%). Five patients recovered kidney function and three patients developed end stage kidney disease (6.7%). Twelve infections were reported requiring antibiotic treatment (26.7%), seven severe infections were documented requiring hospitalisation (13.3%) and one patient died (2.2%). Conclusion An early assessment of treatment response assists adjusting vasculitis therapy. Adjusting management to the patient's individual immunological and treatment response may result in better outcome with less treatment toxicity.