Efficacy and safety of rituximab for IgG4-related pancreato-biliary disease: A systematic review and meta-analysis

Background: Type I autoimmune pancreatitis (AIP) and IgG4-related sclerosing cholangitis (IgG4-SC) belong to the IgG4-related disease (IgG4-RD) spectrum. Both entities respond to glucocorticoids, but iatrogenic toxicity associated with prolonged steroid therapy and relapse represent relevant clinical concerns in the long-term. Rituximab is increasingly used as an effective alternative strategy to induce remission but data regarding the safety and efficacy of B-cell depletion therapy for pancreato-biliary involvement of IgG4-RD are limited. We performed a systematic review and meta-analysis to estimate the rate of remission, flare, and adverse events (AEs) occurring in pancreato-biliary IgG4-RD following rituximab treatment. Methods: The MEDLINE, SCOPUS, and EMBASE databases were searched from inception to December 2020 to identify studies reporting the outcomes of IgG4-related pancreato-biliary disease after treatment with rituximab. Studies involving ≥2 patients were selected. In case of duplicated studies, the most recent or the one with the biggest N were chosen. The study was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Pooled effects were calculated using a random-effect model and expressed in terms of pooled remission, relapse, and AEs rates. Results: Seven cohort studies met inclusion criteria and 101 patients were included. Reasons for rituximab administration were new disease onset (18.5%), disease flare after glucocorticoids (63.5%), and glucocorticoids intolerance (17.9%). The median follow-up time was 19 months. The pooled rate of complete response at 6 months was 88.9% (95%CI 80.5–93.9) with no heterogeneity (I2 = 0%). The pooled estimate of relapse rate was 21% (95%CI 10.5–40.3) with moderate heterogeneity (I2 = 51%). A higher rate of relapse (35.9%, 95%CI 17.3–60.1) was reported in studies including patients with multiorgan involvement (OOI). The median time to relapse was 10 months. The pooled estimate of rituximab-related AEs was 25% (95%CI 8.8–53) with substantial heterogeneity (I2 = 73.6%). No publication bias was observed. Conclusion: Treatment of IgG4-related pancreato-biliary disease with rituximab is associated with high remission rate, a higher relapse rate in the presence of OOI, and limited AEs. Randomized controlled trials with adequate power are needed to confirm these findings.