This study consists of a 1-year randomized control period (RCP), followed by an additional 1-year open label extension (OLE) period.~To enter the Screening Period (Day -28 to Day -1), patients must have active IgG4-RD signs/symptoms (i.e., flare) that require steroid therapy. On Day 1, patients will be randomized in a ratio of 1:1 to receive either obexelimab or placebo administered as subcutaneous (SC) injections. All patients will begin a steroid taper on Day 1 to discontinuation by Week 8.~Patients will be monitored for flares during scheduled in clinic visits and any unscheduled visits. The primary endpoint is time to first IgG4-RD flare that requires initiation of rescue therapy in the opinion of the investigator and the Adjudication Committee (AC).~Following the 52-week RCP, patients will have the opportunity to continue in an OLE period where all patients will receive obexelimab. Patients who do not wish to enroll into the OLE period will return for an in-clinic safety follow-up visit 8 weeks after the Week 52 visit (i.e., Week 60).~Including screening and follow-up, the maximum duration of participation in this study for an individual patient is 116 weeks (i.e., 28-day screening, 52-week RCP, 52-week OLE, and an 8-week follow-up).
This study aims to examine the efficacy and safety of obexelimab for the prevention of flare of IgG4-related disease (IgG4-RD)