Sanofi's Genzyme unit suffered a setback after a phase III trial showed that its multiple sclerosis (MS) drug candidate teriflunomide was no better than interferon beta-1a as a treatment for patients with relapsing forms of the disease.
The TENERE study compared two oral doses of teriflunomide (7mg and 14mg once daily) to standard-dose treatment with Merck KGaA Rebif brand of interferon beta, but found Sanofi's drug was no better at preventing treatment failure and cutting the number of relapses patients suffered in a year.
In the study, 48.6 per cent of patients receiving 7mg teriflunomide and 37.8 per cent of those on the higher dose relapsed or discontinued treatment over the course of the trial, compared to 42.3 per cent of patients on Rebif.
While teriflunomide was as effective as Rebif, Genzyme had been hoping to show superiority to help position its drug against Novartis' Gilenya (fingolimod), the first oral treatment for MS to reach the market which achieved sales of $153m in the third quarter of 2011.
Teriflunomide will also face additional competition from a crop of other orally-active MS drugs in late-stage development, notably Teva's laquinimod and BG-12 (dimethyl fumarate) from Biogen Idec, which has the world's largest MS franchise at the moment headed by its Avonex (interferon beta-1a) product.
Despite the competition, analyst Eric Le Berrigaud of Bryan, Garnier told Bloomberg that teriflunomide could still have sales of €500m in 2019 if approved.
Teriflunomide was filed with the US Food and Drug Administration (FDA) in August this year under the Aubagio trade name, and a European filing is expected in the first quarter of 2012.
Genzyme said it would incorporate the TENERE data into its European filing, along with recently-reported results from the placebo-controlled TEMSO trial which showed that the drug cut the risk of annual relapses by around a third.
Sanofi is also developing a monoclonal antibody-based therapy for MS - called Lemtrada (alemtuzumab) - which came out of its $20.1bn acquisition of Genzyme earlier this year.
Lemtrada proved more effective than Rebif in a trial reported in November, and Sanofi has said it intends to move ahead with a regulatory filing for the drug next year.