Biogen says Tecfidera sales slow, delays data readout on Alzheimer's drug

(Reuters) - Slowing sales of Biogen Inc's key oral multiple sclerosis (MS) drug Tecfidera and a delay in a data readout for its keenly watched Alzheimer's drug sent the company's stock down as much as 8 percent on Friday.

The U.S. biotechnology company posted lower-than-expected quarterly profit and revenue, saying Tecfidera's "challenging" quarter was hit by an overall slowdown in the MS market, which has been weighed down by discounting, a single case of a serious brain infection, and the effect of a stronger dollar.

A number of patients are switching to the Biogen's recently launched interferon-based MS drug Plegridy, which has also eaten into Tecfidera sales.

If Tecfidera's U.S. trajectory does not improve, Biogen's revenue growth may come in at the lower end of its previously issued forecast, Chief Financial Officer Paul Clancy said.

Tecfidera sales rose to $824.9 million in the first quarter ended March 31 from $506 million a year earlier, but came in well below consensus projections of about $931 million, according to Deutsche Bank.

Despite sales of the blockbuster treatment falling about 10 percent from the prior quarter, Clancy said Tecfidera would still be the largest contributor to the company's overall revenue growth.

Biogen's market value has more than tripled in the last three years to more than $100 billion due to its lucrative roster of MS drugs.

The company's attempts to diversify its pipeline received a boost last month when better-than-expected early-stage results for its drug to treat Alzheimer's sent its stock to an all-time high.

The drug, aducanumab, is the first to significantly slow cognitive decline and reduce brain-destroying plaque in early-stage patients, rekindling hope of a cure for a disease that affects more than 15 million people worldwide.

However, Biogen said on Friday that data on a 10 mg dose of the drug would not be available until next year, although data on a 6 mg dose would be available in July.

Many investors are concerned that, given the 10 mg titration delay, the major 2015 catalyst has now been moved to 2016, Evercore ISI's Mark Schoenebaum said.

Surprisingly, the company still plans to initiate late-stage development of aducanumab in the second half of 2015, RBC Capital Markets analyst Michael Yee said.

Cambridge, Massachusetts-based Biogen's stock was down about 5.8 percent at $405.27 on the Nasdaq.

(Editing by Simon Jennings)