SEATTLE -- Immunex Corp. on Tuesday received Food and DrugAdministration approval to market its Leukine granulocytemacrophage colony stimulating factor (GM-CSF).

Anticipating the action, investors have driven Immunex stockup about 45 percent since Feb. 21, when the FDA firstapproved a colony stimulating factor, AmgenLs G-CSF, trade-named Neupogen.

Immunex (NASDAQ:IMNX) closed yesterday up $2 at $52.50.

Leukine, which will not immediately compete with Neupogen,will be used to speed bone marrow recovery in patientsundergoing autologous bone marrow transplants to treat non-Hodgkin's lymphoma, Hodgkin's disease and acutelymphoblastic leukemia. About 5,000 bone marrow transplantswere performed worldwide in 1990.

Leukine will be sold in 250-microgram and 500-mcg vials, andwill cost $85 and $160 per vial, respectively. Treatmentconsists of an intravenous infusion of 250 micrograms once aday for 21 days.

Denise Gilbert, a pharmaceuticals analyst at County NatWestSecurities in San Francisco, has estimated the annual U.S.market for GM-CSF for bone marrow transplants at $15 million.

The FDA is reviewing separately Leukine to treat bone marrowfailure. Meanwhile, the company is conducting Phase IIIclinical trials of GM-CSF to treat low white blood cell counts inpatients receiving chemotherapy for ovarian cancer, small celllung cancer and breast cancer.

Amgen's Neupogen has been approved for use to preventinfections after chemotherapy for non-bone marrow cancers.Jeffrey Casdin, a biotech analyst for Oppenheimer & Co. Inc. inNew York, estimated that Amgen could reap $500 million fromU.S. sales of Neupogen in each of the next three years.

Schering-Plough Corp. also has a GM-CSF product under FDAreview.

Immunex developed its GM-CSF in collaboration with Hoechst-Roussel Pharmaceuticals Inc. of Someville, N.J. Immunex andHoechst have non-exclusive U.S. marketing rights to GM-CSF.Hoechst will independently market GM-CSF under the tradename Prokine.

Immunex also announced a three-year agreement with VHASupply Co., a division of Voluntary Hospitals of America Inc. toprovide VHA member hospitals with Leukine.

-- Karen Bernstein BioWorld Staff

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