POS0701 PROSPECTIVE STUDY OF SEVERE INFECTIOUS EVENTS AND IMMUNE RECONSTITUTION AFTER RITUXIMAB IN AUTOIMMUNE DISEASES (2024)

Results: The anticipated number of inclusions was not met because of the SARS-CoV-2 pandemic, which limited RTX prescription and patients’ recruitment. Seventy-two patients were included. There were mostly women (45/72, 62%) presenting with autoimmune cytopenia, connective tissue diseases, organ-specific AID, systemic vasculitis, acquired hemophilia, and other AID. All patients experienced deep B cells depletion and decreased neutrophils count. Both were not influenced by baseline characteristics according to the mixed models. CD4+ and CD8+ T cells count varied over time, with a more profound depletion at M3 and M9 (Figure 1A and B). Mixed model revealed that the use of immunosuppressants (IS) prior to RTX was associated with a more pronounced decrease in CD8+ T cells (p-value: 0.022) and concomitant use of IS at baseline was associated with a more pronounced decrease in CD4+ T cells (p-value: 0.003). We observed a progressive depletion of IgG, IgM, and IgA over time between baseline and M9 (Figure 1C, D and E). HG occurred in 9 patients at M3, 6 at M6, 9 at M9, and 5 at M12. The mixed model revealed that concomitant use of glucocorticosteroids (GC) ≥ 10 mg/day was associated with a more pronounced decrease in IgG rate in the first 6 months (p-value: 0.036). Concomitant use of IS influenced IgM evolution over time (p-value: 0.013). A history of GC ≥ 10 mg/day was associated with a more pronounced decrease of IgA rate during follow-up (p-value: 0.023) and IS use prior to RTX injection influenced the evolution of IgA rate over time (p-value: 0.037). We observed 10 SIE in 9 patients. Three patients received IgIV for immunomodulatory indication (2g/kg), including 2 during the first 3 months of follow-up.