Actemra, Roche’s first-in-class biopharmaceutical, is safe and effective in rheumatoid arthritis (RA), according to research presented this week at the American College of Rheumatology’s Annual Scientific Meeting in Boston, USA.

Actemra (ocilizumab), a humanised antibody, blocks the receptor for interleukin-6 (IL-6), a cytokine (protein messenger) that helps maintain inflammation in rheumatoid arthritis. During the study, 623 patients received tocilizumab (8mg/kg or 4 mg/kg) or placebo intravenously every four weeks for 24 weeks. All patients also received weekly doses of methotrexate throughout the study. Patients could not receive any other disease-modifying anti-rheumatic drugs.

ACR 20, the main outcome, requires a 20% improvement in the number of tender and swollen joints as well as a 20% reduction in at least three of the following: pain; level of disability; overall self-assessment; overall physician assessment; and level of acute phase reactants. The latter indicate the level of inflammation in the body.

After 24 weeks, 59% and 48% of patients receiving tocilizumab at 8mg/kg and 4mg/kg respectively achieved ACR 20. This compared with 27% in the placebo group. Furthermore, 22% and 12% of those taking tocilizumab 8mg/kg and 4 mg/kg respectively showed ACR 70 (a 70% improvement as outlined above). Only 2% of patients on placebo showed ACR 70. Twenty-one patients even achieved ACR90: 5.4% and 4.7% taking tocilizumab 8mg/kg and 4 mg/kg respectively. No patient on placebo attained ACR90.

In general, adverse events were similar in the placebo and tocilizumab groups. However, tocilizumab seems to be associated with more serious infections (2.9% and 1.4% respectively in the 8mg/kg and 4 mg/kg groups) than placebo (1%).

“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 study investigator Josef Smolen, professor of medicine at the Medical University of Vienna.

Analysts expect Roche to file Actemra for regulatory approval in Europe and the US by the end of 2007. They predict sales of up to 2 billion Swiss francs (1.2 billion euros).