Primary IgA Nephropathy| IONIS-FB-LRx

Inclusion Criteria

Females must be non-pregnant and non-lactating, and either surgically sterile or post-menopausal OR use a highly effective method of birth control
Biopsy-proven primary immunoglobulin A (IgA) nephropathy
Hematuria
Proteinuria

Exclusion Criteria

Clinically significant abnormalities in medical history (e.g., dementia, stroke, acute coronary syndrome, thrombocytopenia, or major surgery within 3 months of Screening)
Diagnosis of primary or secondary immunodeficiencies of B-lymphocyte function, splenectomy, or history of recurrent meningococcal disease
Active infection 30 days prior to study
Estimated glomerular filtration rate (eGFR) ≤ 40 milliliters per minute per 1.73 square meters (mL/min/1.73m^2) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)
Presence of another renal disease including, but not limited to, diabetes and/or diabetic nephropathy, thin basement membrane disease, Alport’s disease, IgA Nephritis (Henoch-Schonlein purpura), lupus nephritis, Minimal Change Disease, post-infectious glomerulonephritis or any other cause of proteinuria or secondary IgA nephropathy (including, but not limited to Celiac disease, Crohn’s disease, human immunodeficiency virus (HIV), liver cirrhosis)
History of renal transplant or another organ transplant
Treatment with another investigational drug, biological agent, or device within 6 months of screening, or 5 half-lives of investigational agent, whichever is longer
Administration of immunosuppressive/immunomodulatory medication 12 months prior to study drug administration, except for short-term treatments.
Other protocol-specified inclusion/exclusion criteria may apply