Roche’s first-in-class interleukin-6 receptor inhibitor Actemra (tocilizumab) has shown significant clinical benefit in patients with moderate to severe rheumatoid arthritis in a fourth Phase III study, meaning the global regulatory filing is on track for later this year.

The so-called AMBITION study examined the use of Actemra monotherapy versus the gold-standard methotrexate in 673 patients with active RA, including a high proportion of patients with early disease. A greater proportion of patients treated with intravenous Actemra every four weeks achieved a significant improvement in disease signs and symptoms following 24 weeks of treatment, compared to patients treated with methotrexate alone. Full data will be unveiled at medical meetings later on in the year.

The AMBITION trial is one of five pivotal studies designed to evaluate Actemra as a potential new treatment for RA; three of the phase III trials – OPTION, TOWARD and RADIATE – have already been completed successfully. An additional Phase III trial evaluating Actemra in RA is ongoing; the two-year study, called LITHE, is expected to report later in 2008. "The study [AMBITION], together with data from the previous three international studies, will form the basis of the regulatory filing for marketing approval later this year," Roche said.

Actemra has been generally well tolerated thus far, with the most frequent adverse events being upper respiratory tract infections, headache, nasopharyngitis and hypertension. Serious infections have also been reported, as with other disease-modifying antirheumatic drugs.

Actemra was first launched in June 2005 in Japan as a therapy for Castleman's disease and in April 2006 filed for the additional indications of rheumatoid arthritis and systemic-onset juvenile idiopathic arthritis.