[Tocilizumab].

IL-6 plays a pivotal role in the pathogenesis of RA. Tocilizumab (TCZ) is a humanized monoclonal antibody to IL-6 receptor, and is now the only biological agent targeting IL-6. The main indication of TCZ for RA patients is those who has been resistant to DMARDs including MTX. TCZ may be also effective for anti-TNF therapy resistant RA. In addition, TCZ can be used effectively as monotherapy. The following screening tests for opportunistic infections should be done before starting TCZ; chest X-ray and tuberculin test or interferon-gamma releasing assay for detecting latent tuberculosis, HBs antigen and HBc antibody for detecting HBV carrier, beta-D-glucan for screening fungal and pneumocystis infection, etc. After starting TCZ, we should be careful for symptoms and signs of infections and allergic reactions, and monitor white blood cell count, liver funtion test and serum lipds.