Subcutaneous tocilizumab for the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is characterized by inflammatory synovitis and is mediated by several cytokines; this includes interleukin-6, whose receptor has been successfully targeted by the humanized monoclonal antibody tocilizumab. Intravenous tocilizumab (TCZ-IV) is registered for use in RA (alone or as combination therapy), systemic juvenile idiopathic arthritis and Castleman disease. Subcutaneous tocilizumab (TCZ-SC) is a desirable alternative to existing subcutaneous biological disease modifying antirheumatic drugs (bDMARDs) targeting tumor necrosis factor. TCZ-SC efficacy has been evaluated in three randomized controlled trials. BREVACTA demonstrated superiority to placebo, and both MUSASHI and SUMMACTA demonstrated non-inferiority to TCZ-IV. TCZ-SC has a similar safety profile to TCZ-IV apart from increased rates of injection site reactions and development of anti-TCZ antibodies (the latter of uncertain clinical significance). TCZ-SC 162mg fortnightly is equivalent to TCZ-IV 4mg/kg fourth weekly; TCZ-SC 162mg weekly is equivalent to TCZ-IV 8mg/kg fourth weekly. TCZ-SC is a suitable bDMARD for RA, particularly when monotherapy is preferred.