A Report on the Clinical Efficacy of Rituximab Administration in Patients with Inborn Errors of Immunity and Autoimmune/Autoinflammatory Manifestations.

It can sometimes be very difficult to control the manifestations of autoimmunity and lymphoproliferation in patients with primary immunodeficiency diseases, and there is no adequate response to first-line treatments. Rituximab (RTX), as a second-line treatment, is efficacious and well-tolerated for the management of these clinical manifestations. This retrospective study was conducted to analyze the clinical, immunological, and genetic findings together with the response rate to RTX therapy in subjects with inborn errors of immunity (IEI) and autoimmune or autoinflammatory manifestations. In this study, 23 individuals with IEI and autoimmune or lymphoproliferation manifestations who received RTX between April 2008 and 2021 were evaluated. Fifteen out of the 23 patients were female. The median age of cases was 12 years.  The moderate and severe adverse reactions, including fever, diarrhea, and anaphylaxis shock, were manifested during RTX infusion in 5 patients. In total, 86.9% of patients responded to rituximab (complete response: n=14, partial response: n=6) while three failed to respond. The median response time to RTX treatment was 50 days. All patients were given monthly intravenous immunoglobulin (IVIG) therapy. Pneumonia and candidiasis occurred in one patient a week after receiving the second injection of RTX. Eight patients expired during follow-up. In conclusion, the response rate of RTX could be improved through administering monthly IVIG for hypogammaglobulinemia treatment following RTX infusion. Early use of rituximab leads to a better response rate in comparison with late use of rituximab in multitreated refractory patients. The efficient cumulative dose of rituximab remains undefined.