Relationship Between T LYmphocytes Depletion and Clinical Response to RITUXimab in Rheumatoid Arthritis (LYRITUX)

Rituximab, an anti CD-20 monoclonal antibody targeting B lymphocytes is prescribed in rheumatoid arthritis (RA) patients refractory to TNF alpha antagonists. According to previous studies, 25 to 50% of patients have an insufficient or absence of response to rituximab at week 24. In a recent retrospective study, a CD4+ T-lymphocytes depletion was observed after a first course of rituximab in RA patients. The absolute CD4+ number at week 12 was 37% (±33) of the baseline value, leading to \< 200 cells/µL in 5% of patients. Interestingly the absence of CD4+ T-lymphocytes depletion was observed in clinical non-responders, suggesting the involvement of T-lymphocytes in the mechanism of action of rituximab. So far no prospective study have supported the usefulness of lymphocyte phenotyping, in particular T-lymphocytes, to monitor rituximab-treated RA patients.