Study Overview:

This study is exploring the effect of a new medicine called povetacicept (ALPN-303) on certain kidney diseases caused by the immune system. These diseases include IgA nephropathy, which affects filtering units in the kidney, membranous nephropathy, which causes thickening of kidney membranes, lupus nephritis, a kidney inflammation from lupus, and ANCA-associated vasculitis, a disease causing blood vessel inflammation.

Study Participation:

• Participants will receive the study drug every 4 weeks for 6 months. There is an option to extend treatment for up to 52 additional weeks.
• Participants must have a biopsy-confirmed diagnosis and meet specific criteria for their disease type.
• People with other kidney diseases, severe kidney problems, or recent serious infections cannot join.

This study aims to see if povetacicept is safe and helpful in treating these diseases. Participants won't be on other immune-suppressing drugs during the study, except for certain allowed medicines. The study requires regular visits to the clinic for treatment and monitoring, ensuring participant safety and effectiveness of the drug.