Biogen Idec's Tecfidera approved in US

Biogen Idec rounded off a great week with US approval for its oral multiple sclerosis (MS) therapy Tecfidera following closely on a green light for the drug in Europe.

Tecfidera (dimethyl fumarate; formerly known as BG-12) is the third orally-active MS treatment to be registered in the US after Novartis' Gilenya (fingolimod) and Sanofi's Aubagio (teriflunomide).

But it's the first MS treatment to affect the Nrf-2 pathway, which provides a way for cells in the body to defend themselves against inflammation, and impressive results in clinical trials have see it tipped to lead the oral MS sector despite being third to market.

"No drug provides a cure for multiple sclerosis so it is important to have a variety of treatment options available for patients," commented the FDA's Russell Katz, who is director of the division of neurology products in the agency's Center for Drug Evaluation and Research (CDER).

"Results from two clinical trials showed that those taking Tecfidera had fewer MS relapses compared to people taking … placebo [while] one of the trials showed that those taking Tecfidera experienced a worsening of disability less often," said the FDA.

Gilenya has already made significant headway in the MS market, racking up sales of $494m in 2011 and $1.2bn last year, while Aubagio posted $9m in sales in its few weeks on the US market following approval there in October. 

Aubagio verdict adds uncertainty outside the US

While US approval is undoubtedly great news for Biogen Idec, prospects in Europe and other non-US markets have been thrown into doubt following a Committee for Medicinal Products for Human Use (CHMP) decision on Aubagio (teriflunomide).

The European regulatory advisory committee declined to give Aubagio a New Active Substance (NAS), despite recommending it be granted marketing authorisation.

The recommendation could have significant repercussions for the emerging oral MS market as low-cost teriflunomide generics could now become available as early as 2016 unless Sanofi can successfully appeal the ruling.

In austere times, particularly in Europe, that ruling raises the possibility of doctors prescribing generic teriflunomide in the first instance, even though clinical trials suggest Biogen's Tecfidera has greater efficacy and safety than its rival.

At peak Tecfidera is expected to reach around $3bn in annual revenues, followed by Gilenya with around $2bn and Aubagio following behind, with its potential wholly dependent on the impact of the NAS decision.