Roche has presented impressive data from a fifth late-stage study of its experimental rheumatoid arthritis drug Actemra which is being touted as a potential blockbuster.

The Switzerland-based company said that results from the 1,196-patient Phase III LITHE trial showed that a greater proportion of patients treated with Actemra (tocilizumab) in combination with the commonly-used RA drug methotrexate, benefited from a significant inhibition of structural damage during 12 months of therapy, compared to those on MTX alone. The firm said this is critical to patients because damage in the joints caused by the disease leads to the disability and pain associated with RA.

Actemra was developed by Roche’s majority-owned Japanese partner Chugai which already sells the drug in Japan for Castleman’s disease, a rare immune disorder, and it was filed there in April 2006 for RA and systemic-onset juvenile idiopathic arthritis. Roche submitted a Biologics License Application to the US Food and Drug Administration in November seeking the go-ahead for Actemra, the first humanised interleukin-6 receptor-inhibiting monoclonal antibody to be filed.

Roche hopes that Actemra will be able to compete with the anti-tumour necrosis factor therapies approved for RA – Abbott Laboratories’ Humira (adalimumab), Johnson & Johnson/Schering-Plough’s Remicade (infliximab) and Wyeth/Amgen’s Enbrel (etanercept). Analysts think it will provide a real alternative to the anti-TNF treatments and estimate sales of around $2 billion if approved.