Biotechnology company Biogen Idec Inc said U.S. health regulators extended by three months the review date of its much-awaited multiple sclerosis (MS) drug BG-12, but analysts said the delay was only a minor setback.

Shares of Biogen were down 2 percent at $150.72 in morning trading on the Nasdaq.

The stock has risen more than 50 percent over the past 12 months, largely on optimism aboutBG-12, which showed robust results in trials and had no safety concerns.

Analysts said the delay would push the review date to March, but added such extensions were not uncommon.

"The registrational studies for BG-12 - DEFINE and CONFIRM - enrolled about 1,200 and 1,400 patients, respectively. Given the size and complexity of the filings, we are not surprised that the FDA would require additional time to review the application," Barclays Capital analyst Anthony Butler said.

The U.S. Food and Drug Administration said it needed additional time to review the application, but did not ask for additional studies, according to Biogen.

Butler and Wells Fargo Securities analyst Brian Abrahams pointed out that Sanofi's oral MS drug Aubagio also had its review extended earlier this year, but was later approved.

BG-12, also known as dimethyl fumarate, would be the second oral MS drug on the market, competing with Novartis AG's Gilenya.

Analysts expect sales of $390 million and $980 million for BG-12 in 2013 and 2014, Barclays's Butler said in a note.

The oral drug is currently also under regulatory review in the European Union, Australia, Canada and Switzerland.

Biogen also markets Avonex and Tysabri to treat relapsing-remitting MS, the most common kind of MS.

Multiple sclerosis affects 400,000 Americans and 2.5 million people worldwide, according to the National Multiple Sclerosis Society.

Source: Reuters © Thomson Reuters 2012 (18/10/12)