Phase III testing shows that a potential new therapy called tocilizumab is safe and effective in the treatment of rheumatoid arthritis, according to research presented recently at the American College of Rheumatology Annual Scientific Meeting in Boston, Mass.
Rheumatoid arthritis is a chronic disease that causes pain, stiffness, swelling, and limitation in the motion and function of multiple joints. Though joints are the principal body parts affected by RA, inflammation can develop in other organs as well. An estimated 2.1 million Americans have RA, most of them women.
Researchers tested the effectiveness and safety of tocilizumab, a new humanized, anti-human IL-6 receptor antibody, in patients with moderate to severe active RA despite being treated with methotrexate. Tocilizumab blocks the function of interleukin-6, a molecule that plays a fundamental role in maintaining the inflammation that affects patients with RA.
623 participants in this double-blind, placebo-controlled, phase three trial were randomly given 8 mg/kg of tocilizumab, 4 mg/kg of tocilizumab, or placebo intravenously every four weeks for twenty-four weeks. All participants received weekly doses of methotrexate throughout the study. No other disease-modifying anti-rheumatic drugs, or DMARDS, were allowed.
Researchers found that a significantly higher proportion of patients treated with tocilizumab showed improvements in the primary endpoint (ACR 20 at 24 weeks). The ACR 20 response was achieved by 59 and 48 percent of patients receiving tocilizumab at 8 and 4mg/kg, respectively, compared to 27 percent on placebo. The more stringent ACR 70 response was achieved by 22 percent of patients treated with 8mg/kg tocilizumab, but only two percent of patients receiving placebo.
The ACR 20/50/70 scoring criteria measures improvement in tender and swollen joint count and improvement in at least three of the following five criteria: pain; level of disability; overall self-assessment; overall physician assessment; and level of acute phase reactants (including the C-reactive protein or sedimentation rate).
Adverse events were similar across all groups of participants. Of 41 serious adverse events affecting approximately six percent of participants in each group, 15 were considered related to the study treatment and 11 led to discontinuation of treatment. Serious infections were observed more often in the participants treated with tocilizumab than the placebo group (2.9 percent in the 8 mg/kg group, 1.4 percent in the 4 mg/kg group, and 1 percent in the placebo group).
“The data prove that IL-6 is importantly involved in the inflammatory response of RA, and that targeting the IL-6 receptor with tocilizumab is a useful novel treatment modality,” said Josef Smolen, MD; professor of medicine; chairman, department of internal Medicine III and division of rheumatology; Medical University of Vienna; Chairman, 2nd department of medicine, Hietzing Hospital; Vienna, Austria; and an investigator in the study.
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