Inclusion Criteria:  Male or female ≥ 18 years of age Biopsy proven IgAN Urine protein ≥ 0.75g/24 hours at Screening despite optimization with ACE inhibitors or angiotensin receptor blockers (ARB) eGFR ≥ 45 mL/min per 1.73 m2 or eGFR < 45 mL/min per 1.73 m2 and ≥ 30 mL/min per 1.73 m2 with a kidney biopsy within 2 years of Screening showing < 50% tubulointerstitial fibrosis Agree to comply with contraception requirements during and for 90 days after study completion.  Exclusion Criteria:  Any secondary IgAN as defined by the investigator Patients who have undergone a kidney transplant Any history of kidney disease other than IgAN Any history of diabetes (Type 1 or Type 2) Seated blood pressure > 140 mmHg (systolic) or > 90 mmHg (diastolic) at the Screening Visit. Patients must be on a stable dose and regimen of an ACE inhibitor or ARB for at least 90 days Pregnancy or breastfeeding.