The purpose of this study is to evaluate the efficacy and safety of subcutaneous blisibimod administration in addition to standard therapy in patients with biopsy proven IgA Nephropathy with persistent proteinuria of between 1-6 g/day.

Inclusion Criteria:

• 18 - 65 years of age, inclusive
• Biopsy-proven IgA nephropathy
• Receiving stable, clinically-optimized ACEI and/or ARB
• Proteinuria ≥ 1g/24hr but ≤ 6g/24hr at 2 consecutive time points

Exclusion Criteria:

• Clinical or histologic evidence of non-IgA-related glomerulonephritis
• IgA nephropathy with greater than 50% glomerulosclerosis or cortical scarring
• Meets eGFR criteria
• History of treatment with oral or parenteral corticosteroids within 3 months or immunosuppressants within 6 months
• Malignancy within past 5 years
• Known to be positive for HIV and/or positive at the screening visit for hepatitis B, or hepatitis C
• Liver disease
• Neutropenia
• Active infection requiring hospitalization or treatment with parenteral antibiotics within the past 60 days or history of repeated herpetic viral infections
• History of active tuberculosis or a history of tuberculosis infection
• Pregnant or nursing