This clinical trial is focused on studying a rare blood disease called Paroxysmal Nocturnal Hemoglobinuria (PNH). PNH is a condition where red blood cells break down too early, leading to various health issues. The study is testing a treatment called danicopan, which is used as an additional therapy alongside another type of medication known as a Complement Component 5 Inhibitor (C5i). The C5i medications being used in this study include Ultomiris and Soliris. Danicopan is taken as a film-coated tablet, while Ultomiris and Soliris are given as solutions for infusion, which means they are administered directly into the bloodstream through a vein.

The purpose of this study is to understand the long-term safety of using danicopan as an add-on treatment for patients with PNH who have previously been treated with danicopan in another study. Participants will continue their treatment over a period of time, during which they will receive either danicopan with a C5i or a placebo. The study will monitor any side effects and changes in health, such as hemoglobin levels, which is a protein in red blood cells that carries oxygen, and other blood-related measurements.

Throughout the study, participants will have regular check-ups to track their health and any changes in their condition. The study aims to gather information on how well danicopan works when used with C5i medications and to ensure it is safe for long-term use. This research is important for improving treatment options for people living with PNH.