Roche has submitted an application to US regulators for its experimental rheumatoid arthritis drug Actemra and analysts are predicting that the Swiss group will soon have another blockbuster on its hands.

The Basel-headquartered firm has submitted a Biologics License Application (BLA) to the US Food and Drug Administration seeking the go-ahead for Actemra (tocilizumab) to reduce the signs and symptoms in adults with moderate to severe RA. The drug is the first humanised interleukin-6 receptor-inhibiting monoclonal antibody to be filed and represents a novel mechanism of action, compared to the anti-tumour necrosis factor therapies for RA – Abbott Laboratories’ Humira (adalimumab), Johnson & Johnson/Schering-Plough’s Remicade (infliximab) and Wyeth/Amgen’s Enbrel (etanercept).

The filing is based on results from five international Phase III studies (more than 4,000 patients in 40 countries) which demonstrated that Actemra as monotherapy or in combination with disease-modifying anti-rheumatic drugs such as methotrexate significantly reduced RA, compared with DMARD therapies alone. Furthermore, patients who had previously seen no benefit from anti-TNF drugs also showed significant improvement after treatment with Actemra. One of these Phase III trials is an ongoing two-year study and is expected to report one-year data evaluating the effect of the drug on the inhibition of structural damage in 2008.

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. A filing in Europe is scheduled for December.

Analysts are backing the drug which they see as a genuine alternative to the anti-TNF treatments and sales of $2 billion are being forecast. If approved, it will further expand Roche’s position in the RA marketplace, which is currently headed by MabThera (rituximab), the first selective B-cell therapy for the disease. The company also noted that ocrelizumab, a humanised anti-CD20 antibody, has entered Phase III development for RA.