An administrative decision was made to terminate the AT-1501-N205 study. This voluntary business-related decision was not related to the safety of tegoprubart (AT-1501). Available safety data demonstrated tegoprubart to be safe and well tolerated.

This is a phase 2a, multicenter, open-label study designed to evaluate the safety and efficacy of AT-1501 in patients with biopsy proven IgAN and at least 0.75 g/24 hours of protein in their urine at the time of screening.

Phase 2a, multicenter, open-label study designed to evaluate the safety and efficacy of AT-1501 in patients with biopsy proven IgAN and at least 0.75 g/24 hours of protein in their urine at the time of Screening. Up to 42 eligible patients will receive one of 2 doses of AT-1501. All patients are scheduled to receive AT-1501 by intravenous infusion every 3 weeks for approximately 2 years.

Inclusion Criteria:

1. Male or female ≥ 18 years of age
2. Biopsy proven IgAN
3. Urine protein ≥ 0.75g/24 hours at Screening despite optimization with ACE inhibitors or angiotensin receptor blockers (ARB)
4. 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
5. Agree to comply with contraception requirements during and for 90 days after study completion.

Exclusion Criteria:

1. Any secondary IgAN as defined by the investigator
2. Patients who have undergone a kidney transplant
3. Any history of kidney disease other than IgAN
4. Any history of diabetes (Type 1 or Type 2)
5. 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
6. Pregnancy or breastfeeding.