A Study to Evaluate the Efficacy and Safety of SHR-1703 in Subjects With Eosinophilic Granulomatosis With Polyangiitis （EGPA）

Inclusion Criteria: Male or female subjects age 18 years or older; Diagnosed with EGPA for at least 6 months; History of relapsing or refractory EGPA； Stable dose of oral prednisone of ≥7.5 mg/day (but not >50 mg/day) for at least 4 weeks prior to randomization; If receiving immunosuppressive therapy (excluding cyclophosphamide), the dosage must be stable within 4 weeks prior to randomization and during the study. Exclusion Criteria: Subjects with other eosinophilic-related diseases; Diagnosed with granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA). Life-threatening EGPA within 3 months prior to randomization; Malignancy history within 5 years prior to randomization; Immunodeficiency; Uncontrolled hypertension； Uncontrolled cerebrovascular and cardiovascular disease; parasitic infection within 6 months prior to randomization; Active infectious disease requiring clinical treatment within 4 weeks prior to randomization; Subjects with a dose of oral prednisone of >50 mg/day within 4 weeks prior to randomization; Oral or intravenous cyclophosphamide therapy within 4 weeks prior to randomization; Intravenous or subcutaneous immunoglobulin within 12 weeks prior to randomization; Biological agents or TH2 cytokine inhibitors used within 12 weeks prior to randomization or within 5 half-lives of the drug; Rituximab or alemtuzumab used within 12 months prior to randomization； Surgical plans that might affect the evaluation; Significant laboratory abnormalities； Prolonged QTc interval or other electrocardiogram abnormalities with significant safety risk at screening; History of drug or substance abuse or alcohol abuse within 1 year prior to screening; Subjects participated another clinical study and received active drug within 30 days or 5 half-lives of the drug prior to screening; Subjects is pregnant, lactating, or planning to be pregnant; Subjects have a known history of hypersensitivity or intolerance to anti-IL-5 mabs or other biological agents; Other conditions unsuitable for participation in the study per investigator judgement.