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

Inclusion Criteria: 1. Male or female subjects age 18 years or older; 2. Diagnosed with EGPA for at least 6 months; 3. History of relapsing or refractory EGPA； 4. Stable dose of oral prednisone of ≥7.5 mg/day (but not \>50 mg/day) for at least 4 weeks prior to randomization; 5. If receiving immunosuppressive therapy (excluding cyclophosphamide), the dosage must be stable within 4 weeks prior to randomization and during the study. Exclusion Criteria: 1. Subjects with other eosinophilic-related diseases; 2. Diagnosed with granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA). 3. Life-threatening EGPA within 3 months prior to randomization; 4. Malignancy history within 5 years prior to randomization; 5. Immunodeficiency; 6. Uncontrolled hypertension； 7. Uncontrolled cerebrovascular and cardiovascular disease; 8. parasitic infection within 6 months prior to randomization; 9. Active infectious disease requiring clinical treatment within 4 weeks prior to randomization; 10. Subjects with a dose of oral prednisone of \>50 mg/day within 4 weeks prior to randomization; 11. Oral or intravenous cyclophosphamide therapy within 4 weeks prior to randomization; 12. Intravenous or subcutaneous immunoglobulin within 12 weeks prior to randomization; 13. Biological agents or TH2 cytokine inhibitors used within 12 weeks prior to randomization or within 5 half-lives of the drug; 14. Rituximab used within 6 months prior to randomization； 15. Surgical plans that might affect the evaluation; 16. Significant laboratory abnormalities； 17. Prolonged QTc interval or other electrocardiogram abnormalities with significant safety risk at screening; 18. History of drug or substance abuse or alcohol abuse within 1 year prior to screening; 19. Subjects participated another clinical study and received active drug within 30 days or 5 half-lives of the drug prior to screening; 20. Subjects is pregnant, lactating, or planning to be pregnant; 21. Subjects have a known history of hypersensitivity or intolerance to anti-IL-5 mabs or other biological agents or previous failure of IL-5/IL-5R therapy; 22. Other conditions unsuitable for participation in the study per investigator judgement.