In an industry dominated by unprofitable micro caps, biotech has only four companies whose market caps exceed $10 billion. Following sector powerhouses Amgen (NASDAQ:AMGN) and Genentech (NYSE:DNA), whose caps top $50 billion, and ahead of Genzyme (NASDAQ:GENZ) at $14 billion, Biogen IDEC (NASDAQ:BIIB) at $22 billion earned its place in this elite group through the development of two blockbuster products: Avonex, for the management of multiple sclerosis, and Rituxan, for non-Hodgkin's lymphoma. Both treatments continue to show strong growth, as Biogen IDEC's 2004 earnings, released yesterday, bear out.

Avonex sales totaled $1.4 billion, up 21% over 2003, and revenues for Rituxan, which Genentech markets, were $615 million, up 25%. Combined, the products have pushed Biogen IDEC over the $2 billion revenue mark, and with the introduction of a new MS drug, Tysabri, the company isn't likely to look back.

Tysabri, which Biogen IDEC shares with Elan (NYSE:ELN), was launched in late 2004, and neither company gave a 2005 sales forecast for the drug. I won't, either, but there's no reason to believe that the drug shouldn't easily become a multibillion-dollar product. It's likely to be approved in Europe, and its use could expand beyond MS management -- data will be emerging from clinical trials for its use in treating Crohn's disease and rheumatoid arthritis.

The merger of Biogen with IDEC Pharmaceuticals in late 2003 created the world's third-largest biotech company. With the success of its treatments and the promise of more to come, Biogen IDEC is positioned to be one of the dominant players in the biotech sector for a long time.

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Fool contributor Charly Travers is an analyst for Motley Fool Rule Breakers and does not own shares of any company mentioned in this article. The Motley Fool has adisclosure policy.