Differentiating the efficacy of tumor necrosis factor inhibitors

Blockade of tumor necrosis factor (TNF) has emerged as one of the most promising therapies in rheumatoid arthritis (RA). Three agents are currently available as specific TNF antagonists, etanercept (Enbrel (R)), infliximab (Remicade (R)), and adalimumab (Humira (R)). Data from noncomparative trials suggest that all 3 agents have comparable therapeutic activity in RA. Etanercept and infliximab have also demonstrated beneficial activity in other inflammatory arthritides [i.e., psoriatic arthritis and ankylosing spondylitis (both agents) and juvenile rheumatoid arthritis (etanercept only)] and inflammatory diseases (i.e., psoriasis and uveitis). Their effects in granulomatous diseases are more variable, with only infliximab demonstrating clear efficacy in the treatment of Crohn's disease, sarcoidosis, and Wegener's vasculitis. In this brief review current efficacy data are summarized and possible explanations for observed clinical differences are explored.