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By Thomas Gryta

Of DOW JONES NEWSWIRES

NEW YORK -(Dow Jones)- Biogen Idec Inc. (NASDAQ-NMS:BIIB) (BIIB) exceeded Wall Street estimates for profit and revenue, prompting a boost to 2008 projections, on strong sales performance of its flagship multiple sclerosis drug Avonex.

Meanwhile, fellow Cambridge, Mass, biotech company, Genzyme Corp. (NASDAQ-NMS:GENZ) (GENZ), also reported strong results for the quarter ended March 31, on sales advances from its broad array of products and reiterated its lowered outlook from earlier this week.

Despite the performance, Biogen shares recently traded down $1.07, or 1.7%, to $63.55. Analyst Chris Raymond with Robert Baird & Co. said investors may be questioning the sustainability of Avonex's impressive sales in the quarter.

Genzyme (NASDAQ-NMS:GENZ) shares are up $1.60, or 2.3%, to $73.15.

The results from Biogen arrive in the shadow of its pending proxy fight with billionaire Carl Icahn, who is seeking seats on the company's board after criticizing its failed sale process last fall.

"We are very pleased with the first-quarter financial results and the strength across all products," said Chief Executive James Mullen in a conference call Wednesday.

The results prompted Biogen to raise its 2008 earnings forecast to $3.25 to $ 3.45 a share from $3.20 to $3.35 and projects 20% revenue growth, hitting the high end of its previous view of 15% to 20%. Analysts expect earnings of $3.30 a share on 18% revenue growth to $3.73 billion.

Biogen's performance was driven by sales of Avonex, which totaled $536.1 million for the quarter, up 19% from a year earlier and beating a consensus estimate of $490 million, according to Bear Stearns.

Paul Clancy, chief financial officer of Biogen, said in an interview that sales of Avonex benefited from foreign exchange, which added 10 percentage points to the drug's 27% rise in overseas sales, and from price increases last implemented in November.

He also noted that the slowing of Avonex's unit growth seen in 2007 was halted in the first quarter, and growth has picked up overseas.

"I think that some renewed marketing and sales focus in the U.S. is paying off," he said.

Biogen recorded sales of MS drug Tysabri - largely considered the company's future growth driver and co-marketed with Elan PLC (ELN) - rose to $114.7 million from $29.8 million last year and beating a consensus of $113 million.

The performance of the two drugs seems to show that Tysabri's growth isn't cannibalizing sales of Avonex. In fact, the company reported that 80% of new Tysabri patients in the U.S.