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Therapeutics options for inflammatory diseases, such as rheumatoid arthritis (RA), have increased tremendously in the past decade with the introduction of biologic therapies, such as monoclonal antibodies or recombinant fusion proteins. These have proven to be highly successful in treating inflammatory or autoimmune diseases, by blocking certain key molecules involved in the pathogenesis of the illness, cytokines (TNF) or immune coactivators (CTLA-4). Thus in rheumatoid arthritis, TNF can be neutralized both by monoclonal antibodies (adalimumab, infliximab) or recombinant inhibitors such as etanercept or CTLA-4 Ig abatacept. All have been marketed and proven to be highly effective in the treatment of RA, and we will discuss parameters which are taken into account to select monoclonal antibody or recombinant inhibitors. These include drug-related (target affinity, pharmacokinetics, mechanisms of action, etc.) and patient - (efficacy and side effects) or disease-related characteristics. Their impact on current clinical practice and future trends are discussed.

Biological therapies consisting of monoclonal antibodies and soluble receptors have revolutionized the care of rheumatologic patients. These therapies ensued from a better understanding of the physiopathology of rheumatologic disorders. Most of the latter have been concerned: rheumatoid arthritis (for about 10 years), psoriatic arthritis and ankylosing spondilitys (for more or less five years). Rheumatology was among the first disciplines to make use of these advances; it continues to benefit from the results of intense research efforts. These developments request from clinicians an increased expertise in immunology.

In 2008 three biological agents against TNFalpha will be available. The combination of infliximab with azathioprine is no longer recommended, as hepatosplenic lymphomas with a particularly bad prognosis have been associated with this combined therapy. Regular maintenance therapy with infliximab is as effective in preventing the development of anti-infliximab antibodies as co-administration of this anti-TNFalpha agent with an immunomodulator. The benefit of regular maintenance therapy is probably linked to the presence of residual trough levels of infliximab between perfusions.

Psoriasis impairs significantly the quality of life. Systemic treatments have inconstant efficiency and dose-dependant toxicity. Since 2004, four biologic therapies - infliximab, etanercept, éfalizumab and adalimumab - are approved in Europe for the treatment of moderate to severe psoriasis, with failure, intolerance or contra-indication to at least 2 "classical" systemic treatments, including phototherapy, methotrexate and ciclosporin. The estimated rate of patients reaching PASI75 at month 3 are as follow: about 80% under infliximab (classical W0-W2-W6 regimen); about 33% and 50% under etanercept, respectively, 25 and 50mg, twice weekly; about 25% under éfalizumab (1mg/kg, weekly); about 70% under adalimumab (40mg, every other week). The 12-month efficiency of biologic therapies in psoriasis is poorly documented. The long term (5-year or more) safety of biologic therapies is not documented. New biologic therapies are under investigation in the treatment of psoriasis: ustekinumab (CNTO-1275), ABT-874, certolizumab (CDP-870), golimumab (CNTO-148). Ustekinumab is approved in Europe since January 2009.