Genzyme Corp. announced Tuesday what it believes to be thefirst orphan drug designation granted to a proposed genetictherapy -- this one aimed at correcting the defective gene thattriggers cystic fibrosis.

Genzyme plans to take its cystic fibrosis gene therapy (CFGT)into clinical trials next year, said Alison Taunton-Rigby,Genzyme's senior vice president of biotherapeutics.

Although other companies are pursuing therapeutic treatmentsof cystic fibrosis, Cambridge, Mass.-based Genzyme is taking adifferent tack.

"There really isn't another company developing a gene therapyapproach," Taunton-Rigby told BioWorld. "Some are working ongene therapies to treat the symptoms of cystic fibrosis, butthey aren't developing drugs to address the underlying causesof the disease."

Genzyme's gene therapy involves inserting a correct copy ofthe defective gene into the patient's own cells, which use thegene to make a protein responsible for producing cystic fibrosistransmembrane regulator. The CFTR protein is normally foundin the cell membranes that line air passages of the lung. CFpatients, who lack the protein, develop thick and viscous fluidin their lungs, often causing infections that damage lung cellwalls, which ultimately leads to death due to pulmonaryinfection.

Genzyme scientists have identified two methods of correctingthe defective gene, both of which have been granted orphandrug designations. In addition to the gene therapy, Genzymehas developed a recombinant CFTR replacement protein.Genzyme received orphan drug designation on this approach inJanuary.

Other companies developing therapeutics for CF includeSynergen Inc., Glaxo Inc. and Genentech Inc.

Synergen has in Phase II trials a secretory leukocyte proteaseinhibitor (SLPI), a naturally occurring protein that regulatesthe elastase enzyme that destroys two proteins important toproper lung function. Glaxo is in early clinical trials withAmiloride, a diuretic used for reducing mucus in the airpassages of CF patients. And Genentech is in Phase III trialswith DNase, an inhaled therapeutic designed to dissolve mucusin lungs of CF patients.

Genzyme's Taunton-Rigby predicted that it will take at leastsix more years before the company has gene therapy productson the market. "These are definitely long-term products, asgene therapy represents a whole new approach to thetreatment of cystic fibrosis," she said. "As yet, we don'tunderstand all the risks and safety issues involved with genetherapy."

Genzyme (NASDAQ:GENZ) develops, manufactures and sellsbiotherapeutic and diagnostic products and services, andpharmaceuticals. The company has received six orphan drugdesignations.

-- Michelle Slade Associate Editor

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