(Updates with background, sales forecast)
By Toni Clarke
March 28 (Reuters) - Biogen Idec Inc has won U.S. approval for its long-acting hemophilia B treatment Alprolix, the U.S. Food and Drug Administration said on Friday.
Hemophilia B is a rare, inherited disorder in which a person's blood does not clot properly, which can lead to prolonged bleeding and bruising. It affects about 4,000 people in the United States and 25,000 worldwide.
Alprolix is a bioengineered version of the blood coagulation factor IX, a protein needed for normal blood clotting. Biogen is developing the drug in partnership with Swedish Orphan Biovitrum AB. It received approval in Canada a week ago.
Hemophilia drugs in general must be infused two to three times a week to prevent bleeding episodes. Biogen's drug needs to be administered once a week or once every 10 to 14 days.
The company is also developing a long-lasting drug, Eloctate, for Hemophilia A, a more common form of the disease, that affects about 20,000 people in the United States. Patients with hemophilia A lack or have reduced levels of coagulation factor VIII.
Current treatments for hemophilia B generate about $1 billion a year, according to Biogen. The market for hemophilia A therapies is worth about $6 billion.
Eloctate would compete with Baxter International Inc's drug Advate. Baxter is seeking to develop its own long-acting version but Biogen is expected to be first to the market.
Alprolix is expected to generate sales of $286 million by 2019, according to Thomson Reuters data. Eloctate is expected to generate sales of $1.1 billion. (Reporting by Toni Clarke in Washington; Editing by David Gregorio)