eMedicineLive

In a breakthrough research, scientists have developed a gene therapy for treating the bleeding disorder, hemophilia B. The therapy was developed at St. Jude Children’s Research Hospital in Memphis and was successfully put to test at a clinical trial at the University College London. Hemophilia B is a genetic condition in which the patients lack Factor IX, required for normal blood clotting. The condition affects one in 30,000 people and is limited to males. It is characterized by painful bleeding episodes.

 

The clinical trial was done on six patients and the results have been published in the online edition of the New England Journal of Medicine. In the clinical trial, Factor IX gene was transported to the liver through an adeno-associated virus (AAV) 8. The vector was introduced through a one time infusion into a vein in the arm. The virus targeted the liver cells and caused a mild infection in some participants, but in the process it transported the correct version of the Factor IX to the liver cells. 

 

Following the infusion of the vector, the levels of Factor IX rose in all six participants from 1% to 3-12 %. Even the modest increase in the levels of factor IX was sufficient to alter the quality of life of the patients dramatically.  The participants have maintained a raised level of Factor IX and do not suffer from bleeding episodes any more. They have been able to participate in marathons and indulge in activities which were not possible for them to do prior to the gene therapy.

 

Some of the participants suffered from elevated level of liver enzymes following the transfusion of the virus due to immune response of the host, but the levels soon returned to normal following treatment with steroids. However, the good news was that even treatment with steroids did not reduce the levels of Factor IX. Encouraged by the results of this clinical trial, scientists want to experiment with something similar for treating Hemophilia A, a far more common bleeding disorder.

 

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