A protocol for targeted B-lymphocyte depletion for the treatment of IgG4-related disease.

Abstract

To determine the clinical outcomes of patients with immunoglobulin 4-related disease (IgG4-RD) treated with a defined B cell depletion protocol using rituximab. Patients were included if they had (1) an IgG4-RD diagnosis at Imperial College Healthcare NHS Trust between February 2017 and October 2022, and (2) >9 months of follow-up data available following the first rituximab dose. The rituximab protocol targeted B cell depletion to < 10 cells/microliter for a maintenance period of two years. Electronic records were used to define patient demographics, serological and radiological variables and treatment responses according to the IgG4-RD responder index (RI). Forty-five patients received induction treatment with rituximab. Two patients had insufficient follow-up data for outcome analysis. All patients responded to rituximab therapy according to the IgG4-RD RI. Most patients (25/43, 58%) were also treated with low-dose glucocorticoids at the time of rituximab induction (median prednisolone dose 5 mg daily) and 4/25 (16%) remained on prednisolone at two years (median prednisolone dose 5 mg daily). Disease flares occurred in 11/43 (26%) patients; 9/11 flares occurred in the presence of B cell repopulation; 2/11 (18.1%) flares occurred in the absence of B cell repopulation (>10 cells/uL). All flares re-treated with rituximab (7/7, 100%) responded positively. Rituximab administration targeting B cell depletion for a two-year period is an effective treatment strategy for IgG4-RD and can limit the cumulative glucocorticoid exposure. Flares are uncommon and typically occur in the setting of B cell repopulation, with good clinical responses to further rituximab administration.