Roche’s plans for a seamless passage towards approval for Actemra have suffered a slight blip after US regulators demanded more information on the rheumatoid arthritis drug.

The US Food and Drug Administration has issued a complete response letter for Actemra (tocilizumab) for the treatment of adults with moderate-to-severe RA. Specifically the agency has requested additional documentation related to the manufacturing of the drug, a novel interleukin-6 (IL-6) receptor-inhibiting monoclonal antibody, “and certain other outstanding components, such as final labelling”.

The FDA’s decision comes as something of a surprise, seeing as how the agency’s Arthritis Advisory Committee voted 10-1 for approval of Actemra at the end of July. However panellists raised concerns about potential side effects, including liver damage but Roche noted that the complete response letter contains no request for any new clinical studies surrounding the efficacy or safety of Actemra as a prerequisite for approval.

The Swiss drugmaker added that it is working “to promptly address any outstanding matters” and “upon satisfactory completion of the FDA's requests and an approved label, Roche does not foresee any issues that would impact the quality, availability and supply of Actemra in the USA”. Chief executive of the firm’s operations in the USA, George Abercrombie, said “we are confident that we will be able to resolve any outstanding matters in the near future”.

The Biologics License Application Roche presented to the FDA in November last year contained data from five Phase III trials involving over 4,000 people. The findings demonstrated that Actemra – alone or in combination with methotrexate or other disease modifying anti-rheumatic drugs – significantly reduced RA signs and symptoms, regardless of previous therapy or disease severity.

The decision by the FDA had a damaging effect on the shares of Roche subsidiary Chugai which launched Actemra in Japan in June 2005 as a therapy for Castleman's disease. In April this year, additional indications for RA, juvenile idiopathic arthritis and systemic-onset JIA were also approved in that country.

When approval does come, Actemra will provide a new option for patients who do not respond to anti-tumour necrosis factor-alpha therapies such as Abbott Laboratories’ Humira (adalimumab), Johnson & Johnson/Schering-Plough’s Remicade (infliximab) and Wyeth/Amgen’s Enbrel (etanercept). Up to a third of patients are not adequately treated with those drugs, Roche has previously stated.