The primary objectives of this study are to characterize ravulizumab pharmacokinetics (PK) and pharmacodynamics (PD), and to evaluate safety and efficacy following ravulizumab IV dosing in pediatric participants with IgAN or IgAVN.

Inclusion Criteria:

• Participant must be 2 to < 18 years of age at the time of signing the informed consent or assent.
• Stable and maximum allowed or tolerated RASI (ACEI and/or ARB) dose for ≥ 3 months prior to Screening with no planned change during Screening through Week 106.
• UPCR ≥ 1.0 g/g from the mean of 3 first morning voids (FMV) collected within 1 week during the Screening Period
• Estimated GFR ≥ 30 mL/min/1.73 m2 during Screening
• Meningococcal infection vaccine
• Haemophilus influenzae type b and Streptococcus pneumoniae vaccine
• Participants who are receiving SGLT2i, DEARA (eg, sparsentan), MRA, ERA, or GLP-1 agonists must be on a stable and maximum allowed or tolerated dose for ≥ 3 months prior to Screening with no planned change in dose through Week 34.
• Established diagnosis of primary IgAN diagnosis based on kidney biopsy within 3 years prior to Screening or during the Screening Period

Exclusion Criteria:

• Diagnosis of rapidly progressive glomerulonephritis
• Secondary forms of IgAN not in the context of primary IgAN or IgAV
• Concomitant clinically significant renal disease other than IgAN or IgAVN
• Clinical remission of IgAN/IgAVN or clinically significant improvement in proteinuria within the last 6 months.
• Uncontrolled diabetes mellitus with HbA1c > 8.5%
• History of kidney transplant or planned kidney transplant during the Primary Evaluation Period.
• History of other solid organ (heart, lung, small bowel, pancreas, or liver) or bone marrow transplant
• Splenectomy or functional asplenia
• Participants with nephrotic syndrome receiving albumin infusions or with acute kidney injury requiring dialysis within the last 6 months prior to Screening.
• Hemolytic uremic syndrome diagnosed any time prior to Screening.
• Planned urological surgery expected to influence kidney function within the study time frame.
• Congenital immunodeficiency
• Active systemic bacterial, viral, or fungal infection within 14 days prior to enrollment
• Received biologics for the treatment of IgAN or IgAVN within≤ 6 months prior to Screening

Alexion has a public commitment to allow requests for access to study data and will be supplying a protocol, CSR, and plain language summaries.