Subcutaneous tocilizumab: recent advances for the treatment of rheumatoid arthritis.

Introduction: Tocilizumab (TCZ) is a humanized anti-interleukin-6 (IL-6) receptor monoclonal antibody that is widely used to treat rheumatic arthritis (RA). When initially introduced, TCZ was administered by intravenous infusion. Since 2013, subcutaneous administration of TCZ has also been offered. Currently, we can choose the TCZ administration route according to patient preference.Areas covered: We summarize TCZ therapy and review recent advances of TCZ-SC therapy. Initially, three pre-clinical phase III randomized controlled trials - MUSASHI, SUMMACTA, and BREVACTA - demonstrated the similar effectiveness and safety between subcutaneous TCZ (TCZ-SC) and intravenous TCZ (TCZ-IV). Several real-world TCZ-SC studies further confirmed these findings. These studies also focused on the influence of body weight. Since TCZ-SC is a fixed dose therapy, the efficacy of TCZ-SC 162 mg q2w was sometimes inadequate in high body weight patients. By contrast, TCZ-SC 162 mg qw therapy achieved a higher trough serum concentration of TCZ than TCZ-IV 8 mg/kg q4w. No additional safety concerns were noted. Finally, possible differences between the IL-6 inhibitor and IL-6 receptor inhibitor are discussed.Expert opinion: There are no appreciable differences between TCZ-SC and TCZ-IV in clinical practice. Thus, TCZ-SC is an attractive option for RA patients.