Tocilizumab: A Novel Humanized Anti-Interleukin 6 Receptor Antibody for the Treatment of Patients with Rheumatoid Arthritis

Abstract

Tocilizumab (TCZ; RoActemra® or Actemra®) is a recombinant humanized monoclonal antibody that acts as an interleukin 6 (IL-6) receptor antagonist. For rheumatoid arthritis (RA), intravenous (IV) TCZ 8 mg/kg every 4 weeks has been approved since 2008 in Japan (where it is also approved for polyarticular juvenile idiopathic arthritis, systemic-onset juvenile idiopathic arthritis and Castleman's disease), and since 2009 in Europe in combination with methotrexate (MTX) for the treatment of moderate to severe active RA in adult patients with inadequate response to, or intolerance of, disease-modifying antirheumatic drug (DMARD) or tumor necrosis factor (TNF) antagonist therapy. It may also be administered as monotherapy in the same dose regimen in patients with methotrexate intolerance or with inadequate response to MTX. Since January 2011 in the United States, the indication for treatment with TCZ for RA patients with an inadequate response to one or more TNF antagonists was extended to patients with moderately to severely active RA, and the recommended starting dose is 4 mg/kg every 4 weeks, with an increase to 8 mg/kg based on clinical response. All of these approvals are based on the effectiveness and safety of the 8 mg/kg dose regimen when administered either as monotherapy or in combination with conventional DMARDs in well-designed clinical studies in adult patients with moderate to severe RA. TCZ at this dose is more effective than placebo, MTX or other DMARDs in reducing disease activity and improving health-related quality of life (HR-QoL). Although there were fewer responses with the 4 mg/kg dose, this dose every 4 weeks was not statistically different to 8 mg/kg when administered in combination with MTX, and this dose is the recommended starting dose in the US. Both doses have also been shown to inhibit structural joint damage in patients with an inadequate response to MTX. Thus, TCZ is an important new treatment option in patients with moderate to severe RA.