Mice that received implants of skin cells modified to contain theerythropoietin (EPO) gene have produced therapeutic levels of EPOfor one year, Transkaryotic Therapies Inc. reported Wednesday atHambrecht & Quist's Annual Life Sciences Conference in SanFrancisco.
TKT of Cambridge, Mass., is continuing the experiments to determinewhether the gene therapy will last the entire lifetime of the animals.Such a therapy could replace the weekly injections of geneticallyengineered EPO that are given to patients with chronic anemiacaused by kidney disease. TKT said the annual cost of such treatment-- which is often lifelong -- is approximately $6,000 per year.
EPO is currently marketed by Amgen Inc. for treatment of chronicanemia. Johnson & Johnson licensed it from Amgen for all indicationsexcept use in kidney dialysis. TKT's president and chief executiveofficer, Michael Forrest, said TKT would have been unable tocommercialize the EPO gene therapy without obtaining a license tothe EPO gene patent from Amgen or J&J. However, he said TKTscientists "have come up with a novel way of activating the existingEPO gene in normal cells in a fashion which absolutely eliminates theneed to get a license."
Forrest explained that within the skin fibroblast cell there is acontrol region -- a gene sequence -- that tells the cell not to makeEPO since EPO is not naturally produced in skin fibroblast cells. Hesaid TKT is able to insert its own control region in the cell thatdeletes the existing control region. The new control region instructsthe cell to produce EPO. In this way, Forrest told BioWorld, EPO isactivated without using Amgen's patented gene sequence.
TKT is developing gene therapies for several diseases. The companyplans to begin clinical trials of human growth-hormone delivery incancer patients suffering from cachexia (muscle wasting) early thisyear. TKT also expects to file an investigational new drug (IND)application later in the year for either a Factor VIII gene therapy forhemophilia A or a Factor IX gene therapy product for hemophilia B.
-- Brenda Sandburg News Editor
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