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

Prior treatment

• Life-threatening EGPA within 3 months prior to randomization;
• Malignancy history within 5 years prior to randomization;
• 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 used within 6 months prior to randomization；
• Surgical plans that might affect the evaluation;
• 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 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;

Other illness

• Subjects with other eosinophilic-related diseases;
• Uncontrolled hypertension；
• Uncontrolled cerebrovascular and cardiovascular disease;
• Other conditions unsuitable for participation in the study per investigator judgement.

Lab values

• Significant laboratory abnormalities；
• Prolonged QTc interval or other electrocardiogram abnormalities with significant safety risk at screening;

Other

• Diagnosed with granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA).
• Immunodeficiency;
• Subjects is pregnant, lactating, or planning to be pregnant;

• 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.