**Study Summary:** This study is for adults with a kidney condition called IgA nephropathy (IgAN). IgAN is when proteins called antibodies build up in the kidneys, causing damage. The study will test a medicine called iptacopan to see if it helps improve the kidneys by looking at clinical and molecular markers over 9 months. Participants will start with a screening and a baseline kidney biopsy (a small sample taken to study the kidney's condition). They will then take iptacopan, 200 mg twice a day for nine months. At the end, another biopsy will check for changes. **Key Points:** - **Duration:** The study lasts for 9 months, with several visits needed. - **Treatment:** Participants will take iptacopan and cannot change the dose during the study. - **Eligibility:** Participants must be 18 or older, have confirmed IgAN, and meet other health criteria. They must also be on specific blood pressure medications and have certain vaccinations before starting. If you're interested and meet the criteria, this study might help understand how iptacopan affects kidney health in IgAN patients.