Two "essentially identical" gene therapy protocols wereapproved by the Recombinant DNA Advisory Committee (RAC)of the National Institutes of Health for treatment of Gaucher'sdisease.
This metabolic disorder leaves the body unable to break downfatty substances in the bloodstream before they accumulate inthe spleen, liver and bones. The disease can lead to anemia,enlarged organs, weakened bones and, sometimes, early death.
Genetic Therapy Inc. (GTI) and Theragen Inc. received approvalfor strategies that would use a retroviral vector to introduce agene for the enzyme glucocerebrosidase, lacking in Gaucher'spatients, to progenitor CD34 blood cells. These treatedprogenitor cells should then produce mature blood cells thatmake the enzyme needed to complete lipid metabolicprocessing.
The disease affects 30,000 patients worldwide and can betreated with an expensive, limited supply ofglucocerebrosidase, extracted from placentas. Genzyme Corp.(NASDAQ:GENZ) of Cambridge, Mass., recently completed PhaseIII trials using its recombinant form of glucocerebrosidase,Ceredase, and Enzon Inc. (NASDAQ:ENZN) of South Plainfield,N.J., has been developing a version of glucocerebrosidaseattached to polyethylene glycol to extend its circulating time.
However, the gene therapy methods that received approvalMonday would bypass the need to produce the enzyme outsidethe body and are intended to provide longer-term relief sincethe blood progenitor cells should produce waves of offspringwith the proper gene.
Genetic Therapy (NASDAQ:GTII) of Gaithersburg, Md., alsoreceived approval to alter precursor blood cells to treat severecombined immune deficiency due to adenosinedeaminase(ADA) deficiency. Known as the "bubble boy" disease, ADAdeficiency is a life-threatening illness that leaves patientswithout a properly functioning immune system.
Theragen of Ann Arbor, Mich., is collaborating on its protocolwith the University of Pittsburgh Center for Human GeneTherapy and the Pittsburgh Genetics Institute.
Gaucher's is a prime target of early gene therapy techniques,said M. James Barrett, GTI's president and CEO, because it iswell-characterized and relatively independent of the level ofenzyme expression.
GTI is also producing vectors for two other trials consideredTuesday. In one, Corey Raffel of the Children's Hospital in LosAngeles proposed introducing the enzyme thymidine kinaseinto dividing tumor cells in children with recurrent braintumors to make the cells vulnerable to the anti-viral drugganciclovir. In the other, Ralph Freedman of the M.D. AndersonCancer Center in Houston sought permission to alter tumorinfiltrating lymphocytes to treat ovarian cancer patients.However, the panel voted to defer approval pending moreinformation about experimental design.
The cancer center received permission on Monday to introducea multidrug resistance gene to progenitor blood cells of ovariancancer patients so the women can receive larger doses of taxol.The trial will use cells selected with the Ceprate SC system ofCellPro Inc. (NASDAQ:CPRO) of Bothell, Wash. The panelunanimously passed this protocol on the condition that theresearchers test the safety of the viral vector.
-- Nancy Garcia Associate Editor
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