Trial of Efficacy and Safety of NS-229 Versus Placebo in Patients With Eosinophilic Granulomatosis With Polyangiitis

Inclusion Criteria: * Ability to provide written informed consent prior to participation in the study. * Male or female subjects aged ≥18 years at the time the informed consent form is signed. * Diagnosis of EGPA: Subjects who have been diagnosed with EGPA based on the history or presence of eosinophilia plus at least a history or presence of 2 of additional features of EGPA. * Subjects receive background OGC dose of ≥7.5 mg/day with or without stable treatment with Mepolizumab/Benralizumab. * Use of adequate contraception. * Other inclusion criteria may apply. Exclusion Criteria: * Current diagnosis of either granulomatosis with polyangiitis or microscopic polyangiitis * Imminently life-threatening EGPA at the time of screening. * History or presence of any form of cancer within 5 years prior to screening. * Serious liver, renal, blood, or psychiatric disease * Severe or clinically significant cardiovascular disease uncontrolled with standard treatment * Active systemic infections (including TB, pneumonia, Pneumocystis pneumonia, sepsis, and opportunistic infections) * Parasitic infection: Subjects with a known parasitic infestation within 6 months prior to screening. * HIV positive status * Active hepatitis due to hepatitis B virus or hepatitis C virus * Known history or presence of venous thromboembolism/venous thrombotic events (deep vein thrombosis and/or pulmonary embolus) * laboratory parameter exclusions: 1. Estimated glomerular filtration rate of \<30 mL/min/1.73 m2 by Chronic Kidney Disease Epidemiology Collaboration equations 2. WBC count \<4 × 109/L 3. Absolute lymphocyte count \<500 cells/mm3 4. Absolute neutrophil count \<1000 cells/mm3 5. Platelet count \<120,000/mm3 6. Hemoglobin \<8 g/dL (\<80 g/L) * Subjects who are pregnant, breastfeeding, or planning to become pregnant during the time of study participation * History of clinically significant drug or alcohol abuse within the last 6 months * Other exclusion criteria may apply.