The purpose of this study is to learn more about long-term safety (good or bad effects) of avacopan and its efficacy (how well it is working) in treatment of antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis.

Avacopan is currently approved as an adjunctive (another treatment used along with primary treatment) treatment in adult people with severe active ANCA-associated vasculitis in the US and is also approved in the EU, Canada, Japan, and other countries.

In this study, avacopan will be compared with a placebo (a drug that looks likes the study medication but does not contain any medication). This is a randomized study, meaning that you will be assigned by chance (like flipping a coin) into a treatment group. You will have an equal chance of being placed in either of the 3 following groups: treatment with avacopan for 5 years in group A, or treatment with avacopan for 1 year followed by placebo for 4 years in group B, or treatment with placebo for 5 years in group C. The study is also a double-blinded study, meaning you and your study doctor will not know what you are receiving, the avacopan or placebo.

The study is sponsored by Amgen, Inc. Participation in the study will require 27 visits to the MUSC main campus over approximately 63 months, and visits will include the following procedures: blood draw, urine collection, physician-led assessments of your disease (for example physical exam and medical history review), and health questionnaires. You will also be provided with a paper diary to record any missed doses/overdoses of the study drug.

Compensation is available for participation.