This is a Phase 2 study to assess the safety, efficacy, pharmacokinetics (PK) and pharmacodynamics of ADX-038 in adults with complement-mediated kidney diseases. The study will enroll Chinese adults with IgA nephropathy, complement 3 glomerulopathy (C3G) and immune complex membranoproliferative glomerulonephritis (IC-MPGN). The study will evaluate ADX-038 administered alone (Part A) and in combination with telitacicept (Part B).

Inclusion Criteria:

• Mean eGFR greater than or equal to 30 mL/min/1.73m2
• Clinical evidence of active kidney disease
• Treated with supportive care including an ACE inhibitor or ARB if applicable
• Willing to receive required vaccinations
• Primary diagnosis of IgAN, C3G or IC-MPGN confirmed by a kidney biopsy

Exclusion Criteria:

• Previous kidney transplant or major solid organ transplant
• Required renal replacement therapy for more than 72 hours
• Rapidly progressive glomerular nephritis or acute kidney injury
• History of recurrent invasive infection
• Current or previous use of C5 or CFB inhibitors (such as eculizumab, ravulizumab or iptacopan)
• Active TB, HIV or other systemic infection
• Abnormal liver function