Inclusion Criteria:
1. Age ≥18 years, male or female.
2. Body weight ≥40 kg, BMI between 15 to 38 kg/m².
3. Diagnosis of primary IgA nephropathy confirmed by renal biopsy within 8 years before screening or during screening.
4. 24-hour urine protein excretion (24h-UPE) ≥0.75 g/24h, or first morning void (FMV) urine protein-to-creatinine ratio (UPCR) ≥0.8 g/g.
5. Estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73m².
6. Previously vaccinated with ACYW135 meningococcal polysaccharide vaccine and pneumococcal vaccine.
7. Received renin-angiotensin system (RAS) inhibitor therapy for at least 12 weeks prior to randomization, with stable treatment at the maximum recommended dose or maximum tolerated dose of RAS inhibitors for at least 4 weeks prior to randomization.
8. Agreement to use at least one effective contraceptive method with partners during sexual activity from signing the informed consent form until 4 weeks after the last administration of the investigational product, and refrain from sperm/egg donation during this period.
Exclusion Criteria:
1. Receipt of aldosterone receptor antagonists, renin inhibitors, or medications significantly affecting creatinine levels within 4 weeks or 5 half-lives (whichever is longer) before first investigational product administration.
2. Continuous use of systemic corticosteroids, immunosuppressants/modulators, or Chinese herbal medicines with immunosuppressive effects within 12 weeks or 5 half-lives (whichever is longer) before first investigational product administration.
3. Treatment with biological agents or complement pathway inhibitors (other than the study drug) within 12 weeks or 5 half-lives (whichever is longer) before first investigational product administration.
4. History of gastrointestinal surgery potentially altering drug absorption/distribution/metabolism/excretion, severe gastrointestinal disorders, or conditions causing dysphagia/recurrent vomiting that may interfere with oral medication intake.
5. Major trauma/surgery within 12 weeks before screening or planned major surgery during the study.
6. Previous bone marrow/hematopoietic stem cell transplantation or solid organ transplantation (e.g., heart, lung, kidney, liver).
7. Known/suspected hereditary complement deficiency, or diagnosed primary/severe secondary immunodeficiency.
8. Poorly controlled blood pressure as assessed by the investigator.
9. Poorly controlled blood glucose as assessed by the investigator.
10. Presence of nephrotic syndrome, rapidly progressive glomerulonephritis, renal pathology showing \>50% glomerular crescents, or \>50% tubular atrophy-interstitial fibrosis.
11. Participation in other interventional clinical trials with pharmacological/device interventions within 4 weeks before screening.
12. Pregnant/lactating women or those planning pregnancy during the study
