#3076 A UK parallel cohort study on renal ANCA associated vasculitis outcomes for avacopan exposed and matched unexposed cohorts

Abstract Background and Aims Avacopan was approved in the UK for severe ANCA associated vasculitis (AAV) in December 2022. The ADVOCATE trial found the differential effect of avacopan on kidney function was greatest in patients with the lowest estimated glomerular filtration rate (eGFR), at highest risk of progression to end stage kidney disease (ESKD). Patients with an eGFR 15 ml/min/1.73 m2, pulmonary haemorrhage requiring invasive ventilation, under 12 months prognosis, use of plasma exchange and dual therapy with cyclophosphamide (CYC) and rituximab (RTX) were excluded from ADVOCATE; all common scenarios in real life practice. We aim to provide further information on these subgroups and evaluate 6 month renal outcome data in the UK. Method Parallel cohort study on renal AAV outcomes for avacopan exposed and matched unexposed cohorts, with severe, active GPA or MPA. 120 patients on avacopan from 7 UK centres have been recruited to date. Controls matched by renal function and age will be presented. Comparisons of ESKD, delta eGFR, eGFR recovery, reduction in proteinuria/haematuria, remission, relapse and mortality will be presented, with subgroup analyses for eGFR15 ml/min/1.73 m2. Steroid exposure will be presented. Results Baseline characteristics of the avacopan cohort are below. Most received oral prednisolone at avacopan initiation (89%, n = 107) and 54% received intravenous methylprednisolone (n = 65). The majority received RTX alone (44%, n = 53) or RTX and CYC combination therapy (43%, n = 52). Fewer received CYC alone (9%, n = 11) and 3% were initiated on alternative immunosuppression (n = 4). 26% (n = 31) underwent plasma exchange and 13% required haemodialysis (n=16). 3% of patients have died. Excluding dialysis dependent patients at presentation, median eGFR was 22ml/min/1.73 m2 (IQR 10-36). eGFR at the time of avacopan initiation was 21ml/min/1.73 m2 (IQR 11-34). Conclusion Avacopan is commonly being used to treat nephritis in patients with a low eGFR, including haemodialysis dependent and elderly patients. Avacopan is frequently used with RTX and CYC combination therapy. 6 month outcome data will provide new data on important patient subgroups excluded from the ADVOCATE trial.