Rituximab-induced hypogammaglobulinaemia in patients affected by idiopathic inflammatory myopathies: a multicentre study

Rituximab (RTX) is an anti-CD20 chimeric monoclonal antibody recommended as off-label treatment in patients with idiopathic inflammatory myopathies (IIM). The present study aimed to evaluate changes in immunoglobulin (Ig) levels during RTX-treatment and their potential association with infections in a cohort of IIM patients. Patients evaluated in the Myositis clinic belonging to the Rheumatology Units of Siena, Bari and Palermo University Hospitals, and treated for the first time with RTX were enrolled. Demographic, clinical, laboratory and treatment variables, including previous and concomitant immunosuppressive drugs and glucocorticoid (GC) dosage were analysed before (T0) and after 6 (T1) and 12 (T2) months of RTX treatment. Thirty patients (median age, IQR 56 (42-66); 22 female) were selected. During the observational period, low levels of IgG (