A Phase 2 Study to Evaluate the Safety, PD, PK, and Clinical Activity of ADX-097 in Participants With IgAN, LN or C3G

Key Inclusion Criteria:

All participants

• Male or female participants aged ≥16 years.
• uPCR ≥0.5 g/g (from the average of 3 first morning voids [FMVs]).
• Screening eGFR ≥30 mL/min/1.73m2 calculated by the Chronic Kidney Disease Epidemiology Collaboration creatinine equation (CKD-EPI GFR).
• Participants receiving a renin-angiotensin-aldosterone system (RAAS) inhibitor, sodium-glucose cotransporter-2 (SGLT2) inhibitor, sparsentan, or atrasenten must have been on a stable dose (at the maximum recommended dose according to local guidelines or maximum tolerated dose) for at least 8 weeks prior to Study Day 1 and the dose is projected to remain stable until completion of the study.

Participants with IgAN only

• Kidney biopsy-proven diagnosis of IgAN with a kidney biopsy that is obtained within 10 years of Day 1 or within 5 years of Day 1 if the participant is known or suspected of also having diabetic nephropathy.

Participants with LN only

• Clinical diagnosis of systemic lupus erythematosus (SLE)
• Kidney biopsy-proven diagnosis of LN with a kidney biopsy that is obtained within 24 weeks of Day 1.
• Diagnosis of active focal or diffuse LN class III or IV

Participants with C3G only

• Kidney biopsy-proven diagnosis of C3G, either dense deposit disease (DDD) or complement component 3 glomerulonephritis (C3GN), with a kidney biopsy that is obtained within 52 weeks of Day 1.
• Participants receiving mycophenolate mofetil (MMF) (or mycophenolic acid) or prednisone ≥10 mg/d or equivalent must have been on a stable dose for at least 12 weeks before Day 1 that is projected to remain stable until completion of the study.

Key Exclusion Criteria All participants

• Rapidly progressive glomerulonephritis defined as a 50% decline in eGFR within 12 weeks of screening.
• Concomitant significant renal disease other than IgAN, C3G, or LN per investigator discretion.
• Participants with a history of and/or presence of anti-factor H antibodies at screening.
• Uncontrolled hypertension with mean seated systolic blood pressure (BP) ≥160 mmHg or diastolic BP ≥100 mmHg based on the average of 2 measurements obtained at approximately 2-minute intervals after the individual has been sitting for 5 minutes.
• Kidney, other solid organs, or bone marrow transplantation prior to or expected to occur during the study.
• History of splenectomy.

Participants with IgAN only

• Secondary forms of IgAN
• Received systemic corticosteroid therapy, oral budenoside, or any other form of immunosuppressive therapy within 12 weeks before Day 1.

Participants with LN only

• Lymphocyte count below 0.5 × 109/L at screening.
• Received any of Cyclophosphamide, Calcineurin inhibitors, IV methylprednisolone, IV immunoglobulin therapy, Belimumab, Obinutuzumab and Rituximab treatments at protocol specified time points.

Participants with C3G only

• Evidence of monoclonal gammopathy of unclear significance, infections, malignancy, autoimmune diseases, or other conditions to which C3G is secondary.
• Received systemic corticosteroid therapy, eculizumab, iptacopan, pegcetacoplan, or any other form of immunosuppressive therapy ≤12 weeks before Day 1, except for MMF (or mycophenolic acid), which is permitted.