Response in patients with pemphigus vulgaris to rituximab therapy. Basis of the biology of B cells.

Rituximab (RTX) is a chimeric monoclonal antibody against CD20, which is present on B lymphocytes on the cell surfaces. Originally used for the treatment of B cell malignancies, recent studies show that RTX induced depletion of B cells resulted in a significant improvement on patients with pemphigus vulgaris (PV). This study enrolled 88 patients treated by the lymphoma protocol. A total of 80.7% had a complete response, 11.8% had a partial response, 5.7% did not respond and 2.3% died. The infection rate was 14.7%. Seventeen percent of patients had recurrence. Only 20.4% of the patients could discontinue concomitant therapies after RTX. The remaining had a reduction in the dosages but continued it. In 11% patients during a six-month period a total of 10 infusions of RTX and intravenous immunoglobulins (IVIg) were given. All patients had a complete response. Partial responders and non-responders were not reported. In two patients (18.2%) a recurrence, which responded to RTX and IVIg, was reported. No mortality or infections were observed. At a follow-up of 32 months post-RTX patients were still in a remission. Though the number of patients treated is limited, clinical outcomes appear to be better and lasting in the protocol using RTX and IVIg compare to RTX alone. One of the explanations for these differences in clinical outcomes may lie in the fact that the biological behavior of B cells in lymphoma patients is different from that in patients with autoimmune diseases.