Trial of the Impact of Sibeprenlimab on Immunoglobulin A Nephropathy Kidney Tissue

A Phase 2b, Multicenter, Open-label, Single-arm Trial to Evaluate the Impact of Sibeprenlimab on Kidney Histopathology Through Repeat Kidney Biopsies in Adolescents and Adults With Immunoglobulin A Nephropathy

This is a phase 2b open-label trial to characterize histopathological biomarkers of disease in immunoglobulin A nephropathy (IgAN) and demonstrate potential changes in response to sibeprenlimab.

Inclusion Criteria:

1. Participants must be at least 16 years of age or older at the time of signing the informed consent/assent.
2. Source-verified kidney biopsy confirmed diagnosis of IgAN.
3. Participant has estimated glomerular filtration rate (eGFR) > 45 mL/min/1.73 m2 using serum creatinine (Chronic Kidney Disease-Epidemiology Collaboration [CKD EPI] creatinine eGFR 2021 equation for those 18 years and older; Chronic Kidney Disease in Children under age 25 [CKiD U25] eGFR equation for those younger than 18 years)

Exclusion Criteria:

1. Participants who are breast-feeding and/or who have a positive pregnancy test result prior to receiving sibeprenlimab.

2. Participant has coexisting chronic kidney disease, other than IgAN.

3. Participant has a serum IgG value <600 mg/dL at screening.

4. Participant is currently receiving or has received within 24 weeks prior to the firstdose of sibeprenlimab, systemic corticosteroids or immunosuppression (note:

   topical, ophthalmic, rectal, intra-articular, inhaled corticosteroids are allowed).

5. Participant has uncontrolled hypertension (defined as systolic blood pressure > 140 mmHg or diastolic blood pressure > 90 mmHg).

6. Participants who would be likely to require prohibited concomitant therapy during the trial.