Novel gene therapy cuts painful bleeding of inherited blood disorder

Scientists involving one of an Indian origin have found that a single treatment with a newly developed gene therapy significantly improved symptoms of bleeding disorder hemophilia B in adults.

The gene therapy developed by researchers at St. Jude Children’s Research Hospital in Memphis have been demonstrated to be safe in a clinical trial conducted at the University College London (UCL) in the U.K.

The findings of the six-person study mark the first proof that gene therapy can reduce disabling, painful bleeding episodes in patients with the inherited blood disorder.

Results of the Phase I study showed that 4 participants stopped receiving protein injections to prevent bleeding episodes after undergoing the therapy and have not suffered spontaneous bleeding.

Several have also participated in marathons and other activities that would have been difficult prior to gene therapy.

“This is a potentially life-changing treatment for patients with this disease and an important milestone for the field of gene therapy. It could have ramifications for the treatment of hemophilia A, other protein and liver disorders and chronic diseases such as cystic fibrosis,” said first author Amit Nathwani, M.D., Ph.D., a faculty member at the UCL Cancer Institute, Royal Free Hospital and NHS Blood and Transplant (NHSBT).

The current study used adeno-associated virus (AAV) 8 as the vector to deliver the Factor IX gene along with additional genetic material into the patient’s liver.

AAV8 was picked because the incidence of natural infection with AAV8 is low. It belongs to a family of viruses that target liver cells but do not cause disease in humans or integrate into human DNA.

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Factor IX levels increased the most in the two study volunteers who received the highest dose of the experimental vector, researchers said.

After treatment, levels of the protein ranged from 3 to 12 percent in those men. Even modest increases that raise Factor IX production to more than 1 percent of normal levels have the potential to dramatically affect a patient”s quality of life and reduce bleeding episodes, said the study’s senior author Andrew Davidoff, M.D., chair of the St. Jude Department of Surgery.

Results of the Phase I study appeared in online edition of the New England Journal of Medicine.

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