Immunex Corp. announced Tuesday that it has received a U.S.patent on its yeast-derived granulocyte macrophage-colonystimulating factor (GM-CSF), the protein the Seattle company ismarketing as Leukine (or Sargramostim).

Patent No. 5,229,496 covers "the human GM-CSF protein with asubstitution converting the 23rd amino acid from arginine toleucine," explained Mary McConnon, communications specialistat Immunex (NASDAQ:IMNX).

It's that substitution that allows the protein to be producedefficiently in yeast, and "served as an important step in themanufacture and approval of the product," added Steven Gillis,Immunex's chief scientific officer.

While the newly issued patent covers the GM-CSF protein,Immunex's patent application (which it filed in October 1984)covering the DNA sequence for GM-CSF is still the subject of anongoing, long-lasting interference battle between Immunex,Genetics Institute Inc. (GI), its licensee Sandoz Corp. andsublicensee Schering-Plough Corp.

"The last action on the interference was in September 1991,when the Patent and Trademark Office issued an order askingGI to show cause as to why the interference should not bedissolved because the subject matter isn't patentable,"McConnon told BioWorld. "There's been no further action fromthe Patent Office."

Meanwhile, Immunex's use patent on GM-CSF, No. 5,078,996,was granted in January 1992. This covers the use of GM-CSF tostimulate anti-cancer activity in immune cells.

Immunex is marketing the white blood cell stimulant Leukineto speed the recovery of patients undergoing autologous bonemarrow transplantation and to improve the survival of cancerpatients whose bone marrow transplants have failed.

In March, Immunex filed an amendment to its product licenseapplication (PLA) to allow use of Leukine for the prophylaxisand treatment of chemotherapy-induced neutropenia.

-- Jennifer Van Brunt Senior Editor

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