The purpose of this study is to see if filgotinib can be safe and useful in the long-term treatment of RA.

During this study, you will be assigned to one of two study drug dose groups as described below. You and your study doctor will not know what study drug dose group you are in. To keep the study double-blinded and dose-blinded, there will be a matching placebo for filgotinib of the dose level that you are not taking. A placebo is a tablet with no medicine in it; the placebo tablets look like the 100 mg or 200 mg filgotinib tablets for this study:

Not applicable.