Background/Purpose: Immunoglobulin G4-related disease (IgG4-RD) is a systemic, immuno-mediated fibro-inflammatory disease that affects various organ systems, with typical pathological findings and increased IgG4 levels. Glucocorticoids are the first-line of treatment however relapse rates are high and our knowledge is limited regarding the effects of immunosuppressives. Case reports on rituximab efficacy in the treatment of IgG4-RD are published in addition to an open-label pilot study. The objective of this study was to evaluate the efficacy and safety of treatment with rituximab in 10 subjects diagnosed with IgG4-RD and followed-up in our clinic.

Methods: This study retrospectively investigated the demographic data, clinical features, laboratory findings, immunosuppressive therapies and the outcomes in 10 subjects who had been followed in our clinic for at least 6 months and met the diagnostic criteria for IgG4-RD by clinical, serological and/or tissue biopsy findings and received at least one course of treatment with rituximab (1000 mg twice two weeks apart). IgG4-RD Response Index (IgG4-RD RI), PET-CT and acute phase reactants were used for disease activity evaluation. 8 subjects receiving rituximab treatment had an exacerbation of the disease under low-dose prednisolone therapy and conventional immunosuppressive treatments. In 2 subjects, rituximab was the first choice of immunosuppressive treatment in addition to prednisolone therapy.

Results: IgG4-RD patients had a mean age of 55 years (43-63; 8 male/2 female) and the mean follow-up period was 47 months. Aortitis-chronic periaortitis was found in 8 subjects followed for IgG4-RD, renal involvement in 4, hepatobiliary-pancreatic involvement in 3, and pericardial and pulmonary involvement in 2. The mean IgG4 level was 519.5 mg/dL (145-1160) and IgG4-RD RI was 10.9 (6-21) at the time of diagnosis. The median follow-up period after the first course of rituximab was 18 months (12-24). Remission was achieved in 9 of 10 patients treated with rituximab and the mean daily prednisolone dosage was reduced to below 5 mg/day. Prednisolone therapy was permanently discontinued in 2 subjects. The unresponsive case had membranous glomerulonephritis. After treatment, the mean IgG4 level was 51.3 mg/dL (6-145) and IgG4-RD RI was 1.2 (0-7). No exacerbation was observed during the follow-up period in 9 subjects in whom remission was achieved, and rituximab was repeated as a maintenance therapy at 6 months of treatment. The subject who had severe nephrotic syndrome during follow-up and was given high-dose prednisolone plus cyclosporine in addition to rituximab treatment died due to pneumonia at 6 months of treatment.

Conclusion: The case series for which the retrospective data are presented, consist mainly of patients managed by rheumatology with predominant involvement being aortitis/periaortitis. Rituximab treatment was found to be effective in terms of achieving and preserving remission, and reducing glucocorticoid doses although retreatment is often necessary. No safety issues that require discontinuation of treatment were identified in this group of patients except a case of severe infection with nephrotic syndrome

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/favourable-response-to-rituximab-for-the-treatment-of-igg4-related-disease-long-term-follow-up-of-10-patients-resistant-to-glucocorticoids-and-immunosuppressives/