GlaxoSmithKline and Genmab’s new leukaemia drug Arzerra is at the centre of a patent infringement suit brought by Roche and Biogen Idec.

Roche and Biogen have filed a complaint in a California court for patent infringement “based on GSK's manufacture, marketing and sale of Arzerra” (ofatumumab) in the USA for the treatment of patients with chronic lymphocytic leukaemia, who have not responded to Genzyme Corp’s Campath (alemtuzumab) or the chemotherapy fludarabine. Arzerra, the first Genmab drug to hit the market, was approved across the Atlantic at the end of October last year, where it is produced and sold by GSK.

The suit has been prompted by a US patent issued to Roche’s Genentech unit and Biogen on March 23 which contains a claim to a method of treating CLL with anti-CD20 antibodies, “wherein the method does not comprise treatment with radiolabelled anti-CD20 antibodies,” Genmab said. The latter added that it will “assess and analyse the claims under the initiated legal action” with GSK “and determine the appropriate action in response to the complaint”.

No other details of the case are available though a GSK spokeswoman told Reuters that the firm does not believe Roche and Biogen’s claims are valid or enforceable. She added that the suit is not aimed at seeking an injunction to prevent the sale of Arzerra, she added.

Last month, Roche and Biogen’s blockbuster Rituxan (rituximab) was approved by the US Food and Drug Administration in combination with the chemotherapy regime fludarabine and cyclophosphamide for people with previously untreated as well as treated CD20-positive CLL. However this month the two firms suspended development ocrelizumab, a humanised anti-CD20 therapy, as a possible treatment for rheumatoid arthritis.