Immunex Corp. said Thursday that its Leukine granulocytemacrophage colony stimulating factor (GM-CSF) has beengranted orphan drug status by the Food and DrugAdministration.

Leukine received FDA approval this month for use in thetreatment of neutropenia, or low white blood cell counts, inautologous bone marrow transplant patients with Hodgkin'sdisease, non-Hodgkin's lymphoma and acute lymphoblasticleukemia.

Immunex estimates that 12,000 patients with these threecancers are candidates for autologous bone marrow transplantsin the United States each year. The average cost of a 21-daycourse of therapy is $3,400, for a potential market of $41million.

Immunex's orphan drug status entitles it to seven years ofmarketing exclusivity for these indications. Immunex, based inSeattle, will share its marketing exclusivity with HoechstRoussel Pharmaceuticals Inc., which co-markets Immunex'sGM-CSF under the name Prokine.

Immunex common stock (NASDAQ:IMNX) closed Thursday at$53.25, down $1.25.

The FDA is still reviewing Immunex's application for approvalfor Leukine to treat bone marrow failure. Orphan drug statusfor that indication is pending. -- Karen Bernstein

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