Examining the efficacy of biologic therapy: are there real differences?

Biologic therapy with anakinra, etanercept, and infliximab effectively reduced the signs and symptoms of active rheumatoid arthritis (RA) in randomized controlled trials. Clinical efficacy was determined by American College of Rheumatology (ACR) response criteria. In patients failing previous disease modifying antirheumatic drug (DMARD) therapy, both anakinra and etanercept were significantly more effective than placebo. In patients with inadequate responses to methotrexate (MTX), addition of anakinra, etanercept, or infliximab to stable MTX therapy was significantly more effective than MTX alone. Etanercept has also shown efficacy in early stage, methotrexate-naive patients. Comparisons of the efficacy of these biologics across clinical studies are problematic due to differences in study design, study conduct, and patient populations. Moreover, ACR response rates do not allow comparisons of agents that each achieve these responses relative to placebo. Until comparative clinical studies are conducted, in which 2 biologics are evaluated using the same protocol and patient population, the only conclusion that can be reached from published studies is whether an individual biologic agent is safe and effective. All 3 biologics - anakinra, etanercept, and inflixmab - are effective.