Rheumatoid arthritis (RA) is a systemic inflammatory disease characterized by 
joint pain, swelling, stiffness, and progressive destruction of the small joints 
of the hands and feet. Treatment of RA has improved over the past decade. With 
multiple cytokines well-known now to play a role in the pathogenesis of RA, 
including tumor necrosis factor alpha, interleukin (IL)-1β, and IL-6, many 
targeted biological treatments against these cytokines have emerged, changing 
the treatment of this disease. Tocilizumab (TCZ) is a recombinant humanized 
monoclonal antibody against the IL-6 receptor and has been approved in many 
countries, including the United States, for the treatment of moderate to severe 
RA in patients who have not adequately responded to one or more 
disease-modifying antirheumatic drugs (DMARDs) or cannot tolerate other approved 
drug classes for RA. The aim of this review is to discuss the role of IL-6 in 
RA, and to provide an overview of the mode of action, pharmacokinetics, and 
safety of TCZ. Furthermore, efficacy studies of TCZ as both monotherapy and 
combination therapy will be evaluated. There have been several important 
clinical trials evaluating the efficacy and safety of TCZ in RA patients; this 
review summarizes this data from 14 key trials with emphasis on Phase III 
trials. Review of these trials provides strong evidence that its use, both as 
monotherapy and in combination with methotrexate or other DMARDs, is an 
effective treatment in reducing the signs and symptoms of RA. TCZ showed 
tolerable safety but care is required for its use since there are some important 
safety concerns including elevated liver enzymes, elevated low-density 
lipoprotein, infections, and gastrointestinal perforations. Additionally, given 
the efficacy of TCZ in the treatment of RA, this review discusses how TCZ may be 
beneficial in the treatment of other autoimmune diseases, spinal disease, 
cardiovascular disease, organ transplantation, and malignancies where elevated 
levels of IL-6 may play a role in the pathogenesis of these diseases.