Trial of Sibeprenlimab in the Treatment of A Nephropathy (IgAN)

Inclusion Criteria:

• Male and female patients ≥ 18 years of age .

• Biopsy-confirmed IgAN. (Patients with an eGFR of 30 to 45 mL/min/1.73m2 must havehad a kidney biopsy performed within 36 months of the screening visit).

• Stable and maximally tolerated dose of ACEI and/or ARB for at least 3 months priorto screening. Patients who are on a stable dose of SGLT2i may participate iftreatment was initiated ≥3 months prior to screening. Patients who are unable totake an ACEI or ARB may participate if their overall management conforms withstandards of care and other protocol requirements.

• Screening urine protein/creatinine ratio (uPCR) ≥ 0.75 g/g or urine protein ≥ 1.0g/day

• eGFR ≥ 30 mL/min/1.73 m2, (for the exploratory cohort only: eGFR 20- <30 mL/min/1.73m2), calculated using the 2021 CKD-EPI equation

Exclusion Criteria:

• Secondary forms of IgAN or IgA vasculitis.

• Coexisting chronic kidney disease other than IgAN.

• Kidney biopsy findings in addition to IgAN including those of diabetic nephropathy,membranous nephropathy, or lupus nephritis. Hypertensive vascular changes areacceptable.

• Kidney biopsy MEST or MEST-C score of T2 or C2 (Oxford IgAN classification). IfMEST-scoring was not performed, the presence of > 50% tubulo-interstitial fibrosis,or crescents in > 25% of glomeruli is exclusionary. This does not apply to theexploratory cohort.

• Nephrotic syndrome

• Serum IgG < 600 mg/dL at screening.

• Chronic systemic immunosuppression, including glucocorticoids, within 16 weeks ofrandomization

• Participation in another interventional clinical trial and receipt of anotherinvestigational drug within 30 days prior to the administration of IMP or 5half-lives from last investigational drug administration, whichever is longer.

• Chronic infectious disease, or acute infectious disease at time of screening.

• Type 1 diabetes, or poorly controlled Type 2 diabetes

• Uncontrolled hypertension

The protocol provides additional information about these and other inclusion and exclusion criteria.