Rituximab Maintenance Therapy Reduces Rate of Relapse of Pancreaticobiliary Immunoglobulin G4-related Disease

Background & Aims: IgG4–related disease (IgG4-RD), a multi-organ fibroinflammatory syndrome, typically responds to steroids. However, some cases are steroid resistant, and pancreaticobiliary IgG4-RD commonly relapses after steroid withdrawal. Rituximab induces remission of IgG4-RD, but the need for and safety of maintenance rituximab treatment are unknown. We compared outcomes of patients with pancreaticobiliary IgG4-RD treated with or without maintenance rituximab therapy. Methods: We performed a retrospective study of patients with pancreaticobiliary IgG4-RD treated with rituximab at the Mayo Clinic in Rochester, Minnesota, from January 2005 through December 2015. The cohort was divided into patients who received only rituximab induction therapy (group 1, n = 14) and patients who received rituximab induction followed by maintenance therapy (group 2, n = 29). We collected data on recurrence of IgG4-RD symptoms and findings, as well as information on evaluations, treatment, and adverse events. Results: Median follow-up times were similar between group 1 (34 mo) and group 2 (27 mo) (P =.99). Thirty-seven patients (86%) were in steroid-free remission 6 months after rituximab initiation. A higher proportion of patients in group 1 had disease relapse (3-year event rate, 45%) than in group 2 (3-year event rate, 11%) (P =.034). Younger age, higher IgG4 responder index score after induction therapy, and increased serum levels of alkaline phosphatase at baseline or after rituximab induction were associated with relapse. Infections developed in 6 of 43 patients, all in group 2 (P =.067 vs group 1); all but 1 occurred during maintenance therapy. Conclusions: In a retrospective study of patients with pancreaticobiliary IgG4-RD, we found rituximab maintenance therapy prolongs remission. Relapses are uncommon among patients receiving maintenance therapy, but maintenance therapy may increase risk of infection. Patients with factors that predict relapse could be candidates for rituximab maintenance therapy.