The primary objective of this study is to evaluate the safety and tolerability of tarperprumig in participants with newly diagnosed or relapsing anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis.

Inclusion Criteria:

• Newly diagnosed or relapsing ANCA-associated vasculitis, GPA and MPA subtypes consistent with the 2022 ACR/EULAR classification criteria for GPA and MPA for whom treatment with rituximab or cyclophosphamide is considered.
• Positive test for antibodies to either PR3-ANCA or MPO-ANCA at Screening or in the past by a quantitative assay (for example, ELISA, bead assay).
• At least one major item, or at least 3 minor items, or at least 2 renal items in the BVAS.

Exclusion Criteria:

• Other systemic diseases that, in the judgment of the Investigator, constitute the primary illness, including but not limited to: eosinophilic granulomatosis with polyangiitis (EGPA), systemic lupus erythematosus, IgA nephropathy and/or IgA associated vasculitis with or without Henoch-Schonlein purpura, rheumatoid vasculitis, Sjogren's syndrome, anti-GBM disease, cryoglobulinemic vasculitis, autoimmune hemolytic anemia, or mixed connective tissue disease.
• Alveolar hemorrhage requiring invasive pulmonary ventilation support at Screening.
• Any diseases or conditions that, in the judgment of the Investigator, present a substantial clinical risk to participate in this study.
• For patients with a previous diagnosis of CKD, patients known to have a stable eGFR for greater than 3 months prior to Screening and a decline less than 25% of previous eGFR at Screening will be excluded.

Alexion has a public commitment to allow requests for access to study data and will be supplying a protocol, CSR, and plain language summaries.