Seragen Inc.'s DAB486IL-2 fusion toxin reduced cancerouswhite blood cells by more than fivefold in a patient sufferingfrom chronic lymphocytic leukemia (CLL).

DAB486IL-2 consists of the toxic portion of diphtheria toxinjoined to interleukin-2 (IL-2). IL-2 targets the toxin to whiteblood cells with high affinity IL-2 receptors. Such receptorsbind tightly to IL-2 and are found primarily on diseased whiteblood cells, such as those that cause leukemia.

Dr. Charles LeMaistre of the University of Texas M.D. AndersonCancer Center in Houston and his colleagues reported in theMay 11 issue of The Lancet that DAB486IL-2 was also able topenetrate solid tumors in the spleen and lymph nodes of theCLL patient. The authors said, "The response of the patientunderscores the potential of genetic and protein engineering inthe development of the fusion toxins as a new class ofbiological responses modifiers."

Hopkinton, Mass.-based Seragen, which is privately held, is alsotesting its fusion toxin as a treatment for autoimmune diseasessuch as rheumatoid arthritis and insulin-dependent diabetes.

Other companies, such as Xoma Corp. and ImmunoGen Inc., aredeveloping immunotoxins in which the plant toxin ricin istargeted to diseased white blood cells by monoclonal antibodiesattached to the toxin.

-- Carol Talkington Verser, Ph.D. Special to BioWorld

(c) 1997 American Health Consultants. All rights reserved.

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