Long-term effects of rituximab in rheumatoid arthritis: clinical, biologic, and pharmacogenetic aspects.

Rituximab selectively targets the B-cell compartment, including rheumatoid factor-positive B cells. Short-term efficacy and safety of rituximab in rheumatoid arthritis (RA) has been established by multicenter randomized placebo-controlled studies. Results of long-term follow-up of the phase II/III clinical trials have confirmed the efficacy and safety of repeated courses of rituximab in the responders. However, mechanisms of action in humans, retreatment regimens, biologic effects on memory B cells and on immunoglobulin levels of prolonged exposure of the immune system to B-cell depletion over time, and pharmacogenetic aspects remain open and intriguing issues of rituximab therapy. Several studies are ongoing to clarify possible clinical and biologic predictors of response to rituximab in RA and in other autoimmune diseases where rituximab has been proven to be effective. Preliminary clinical and pharmacogenetic results of our cohort of RA patients managed with rituximab from the year 2000 are presented.