Study to Evaluate the Efficacy and Safety of MY008211A in Subjects with Primary Immunoglobulin a Nephropathy (IgAN)

Inclusion Criteria: 1. Males or females ≥ 18 and ≤ 75 years of age at Screening. 2. Estimated GFR(eGFR) ≥30 mL/min/1.73m2. 3. Subjects with a biopsy-confirmed diagnosis of IgAN. 4. Urine protein ≥0.75 g/24h from a 24h urine collection. 5. All patients must have been on stable supportive care including a maximally tolerated dose or approved maximal dose of ACEi or ARB therapy for at least 90 days prior to the first administration of study drug. 6. Subjects who received SGLT2i must have been on a stable treatment with the maximum allowed or tolerated dose prior to the first administration of study drug. 7. Vaccination against Neisseria meningitidis(MenACWY) is required within 3 years. 8. Vaccination for the prevention of S. pneumoniae is required within 5 years. Exclusion Criteria: 1. Systolic blood pressure \>130 mm Hg or diastolic blood pressure \>80 mm Hg. 2. Presence of any secondary IgAN. 3. Presence of rapidly progressive glomerulonephritis. 4. Presence of other chronic kidney diseases. 5. Patients with a diagnosis of type 1 or type 2 diabetes mellitus. 6. A history of invasive infections caused by encapsulated bacteria, e.g., meningococci or pneumococci. 7. Patients previously treated with immunosuppressive agents exposure within 90 days prior to start of study drug dosing. 8. Patients previously treated with traditional Chinese medicine containing immunosuppressive ingredients within 90 days prior to start of study drug dosing. 9. Patients who had been treated with any systemic corticosteroids within the 180 days before treatment ≥20 mg/d for primary IgAN indication. 10. Patients who previously have received biologic agent or monoclonal antibodies prior to start of study drug dosing within 5 half-lives or 30 days (whichever is longer). 11. Patients who have received live/attenuated vaccines within the 4 weeks prior to randomization, or plan to receive during the trial.