Remission Time after Rituximab Treatment for Autoimmune Bullous Disease: A Proposed Update Definition
Skin Pharmacology and Physiology
imab has also been indicated in the treatment of nonmalignant disorders such as refractory rheumatoid arthritis and polyangiitis. After the successful treatment of CD20(+) B follicular lymphoma-associated paraneoplastic pemphigus [1, 2] , multiple case reports and an increasing number of series of pemphigus and different autoimmune bullous diseases treated with rituximab have been published. Rituximab induces a prolonged decrease in normal B lymphocyte and immunoglobulin levels. There is a
... lack of data about mechanisms involved in rituximab metabolism and elimination. The estimated median half-life of drug in autoimmune disease was 12-36 days  . After 3 months of treatment, rituximab median concentrations of 25 μg/ml were observed in responder patients with follicular non-Hodgkin lymphoma  and a median of 12.9 μg/ml in patients with severe pemphigus  . A single course of rituximab usually leads a depletion of B cells from peripheral blood typically lasting for 7-8 months, with levels returning to normal after 1 year; however, clinical benefit can persist for several months longer  . A therapeutic endpoint is a very important tool to evaluate the therapeutic response in clinical trials. In 2005, a consensus statement identified two late endpoints of disease activity in pemphigus  : complete remission off therapy and complete remission on therapy; both definitions apply to patients without lesions for at Abstract A therapeutic endpoint is a very important tool to evaluate response in clinical trials. In 2005, a consensus statement identified two late endpoints of disease activity in pemphigus: complete remission off therapy and complete remission on therapy, both definitions applying to patients without lesions for at least 2 months. The same period of time was considered for partial remission off/on therapy. These definitions were later applied to bullous pemphigoid and are considered in most studies on autoimmune bullous disease. These endpoints were established for different adjuvant agents, but at that moment, rituximab was not considered. Rituximab is known for the long duration of its effect, and in most studies relapses have been reported later than 6 months after treatment. In our opinion, time to remission after rituximab treatment should be redefined.