Avacopan in Crescentic Immunoglobulin A Nephropathy (IgAN)

The purpose of this study is to evaluate the efficacy and safety of Avacopan together with low-dose glucocorticoid in the treatment of patients with crescentic Imunoglobulin A Nephropathy (IgAN) and high risk of progression.

Inclusion Criteria * Age \> 18 years * Kidney biopsy showing crescentic IgA nephropathy within 6 months of enrolment (MEST-C-score =C1/C2). * Quantified creatinine clearance \>20 ml/min/1.73m2 * Quantified Proteinuria \> 750 mg/24h based on a 24h urine collection while on maximum tolerated dose of RAS blockade * Hematuria defined as \>10 RBC/hpf or hemoglobinuria \>1+ * Patients need to be in adequate supportive care (blood pressure \20 mg/day within 1 month prior to enrollment * Secondary IgA nephropathy (associated with gastrointestinal diseases, infection, autoimmune, malignancy, respiratory tract, or skin) * ANCA-associated vasculitis or other vasculitis diagnostic defined by ACR criteria/Chapel Hill Consensus conference * Contraindication to use any of the protocol treatments (glucocorticoids, avacopan) * Use of a strong/moderate CYP3A4 inducer * Initiation of SGLT2 inhibitors is not allowed once patient has been enrolled in the study. Patients who have been on an SGLT2 inhibitor prior to enrollment on the study may continue on this therapy, at the same dose. No dose increase is allowed. * Active, untreated and/or uncontrolled chronic liver disease (chronic active hepatitis B, untreated hepatitis C, uncontrolled autoimmune hepatitis, cirrhosis * Unable to give written consent form * As a safety measure patients who are pregnant or lactating will not be enrolled in the study.