A 50-year old man suffering from haemophilia A last week became the first person to receive in vivo gene therapy for his condition. The genetically inherited blood disorder affects about 1 in 10,000 men. Affected men carry a defect in the gene for the blood-clotting protein, factor VIII, which can result in potentially life-threatening bleeding episodes. Unlike existing therapies, in vivo gene therapy offers the possibility of a long-term treatment by supplying a functional copy of the factor VIII gene to the body. In previous trials of ex vivo gene therapy for the disorder, cells were taken from a patient, grown in culture, genetically modified and then transferred back to the patient.
The ground-breaking in vivo therapy uses a modified retrovirus which delivers its genetic payload mainly to the liver and spleen. Researchers anticipate that the factor VIII gene will permanently integrate into a cell's genetic material to effectively become a drug-producing factory.
The therapy, designed and initiated through the California-based Chiron Corps., is part of a phase I clinical trial performed at the University of Pittsburgh Medical Center.