Systematic Review of Tocilizumab for Rheumatoid Arthritis: A New Biologic Agent Targeting the Interleukin-6 Receptor

Background: Tocilizumab (TCZ), a humanized anti-interleukin-6 receptor monoclonal antibody, represents a new treatment strategy for patients with rheumatoid arthritis (RA) and is currently approved in the United States for RA patients who have failed to improve with at least one anti-tumor necrosis factor therapy. Objective: The goal of this study was to summarize the efficacy and safety profile of TCZ. Methods: A systematic literature review was conducted to identify English-language articles within PubMed and the Cochrane Library from January 1989 to August 2011 reporting results from Phase III TCZ double-blind, randomized controlled trials (RCTs), noncontrolled clinical trials, and open-label extensions with a duration >= 6 months. Study outcomes had to include at least one of the following: American College of Rheumatology (ACR) 20, 50, or 70 response rates; tender/swollen joint count; Health Assessment Questionnaire-Disability Index; radiographic outcomes and drug persistence. Phase II RCTs were included only if they contained relevant information not available in Phase HI RCTs. Relevant studies were selected to evaluate TCZ's pharmacokinetics and pharmacodynamics. Results: Ten published clinical trials (7 Phase III, 3 Phase II) for TCZ were retrieved (7833 articles initially identified) from PubMed and 31 from the Cochrane library. Compared with methotrexate (MTX) monotherapy, TCZ 8 mg/kg IV monotherapy had higher rates of ACR20 (P < 0.001), ACR50 (P = 0.002), and ACR70 (P < 0.001) scores at week 24. TCZ 8 mg/kg IV plus oral MTX had a higher ACR20 response rate than oral MTX plus placebo in patients with RA who failed to respond to MTX or anti-tumor necrosis factor therapy (P < 0.001). Patients receiving TCZ 8 mg/kg had less radiographic progression on the Genant-modified Sharp score (85% had no progression) than the control group (67% had no progression) (P < 0.001). The rate of serious infections was 4.7 events/100 patient-years of exposure in the TCZ groups. A greater frequency of neutropenia, thrombocytopenia, hyperlipidemia, and transaminitis was observed with TCZ compared with placebo. Conclusion: The short-term efficacy and safety profile of TCZ is promising. Additional long-term safety data are needed to better characterize the risk-benefit profile of this agent. (Clin Ther. 2012;34:788-802) (C) 2012 Elsevier HS Journals, Inc. All rights reserved.