(Vienna, 09 April 2025) A new type of gene therapy to treat the severe form of haemophilia B has been carried out in Vienna for the first time in Austria. This treatment for the inherited bleeding disorder has the advantage over previous therapies and needs to be administered once as an intravenous infusion and is effective for years.
Haemophilia is a hereditary blood clotting disorder in which the blood does not clot properly. As a result, affected people bleed for longer than healthy people after injuries or develop spontaneous bleeding, particularly into joints, with serious consequences. The disease is usually caused by a deficiency or lack of certain clotting factors (factor VIII in haemophilia A or factor IX in haemophilia B). It almost exclusively affects men, as it is inherited X-linked. Treatment usually involves regular intravenous administration of the missing coagulation factors as prophylaxis to prevent bleeding.
In this gene therapy (active substance etranacogene-dezaparvovec), a functional gene for the missing coagulation factor IX is introduced into the liver cells of patients undergoing treatment using a modified viral vector, in this case an adeno-associated virus (AAV). The liver cells then begin to produce the missing coagulation factor, which eliminates the need for regular factor infusions for prophylaxis. This does not interfere with the germline of the cells, which is responsible for passing on the genetic material, but only directly as an addition to the cells in the liver that are responsible for producing the coagulation factor.
"Compared to previous treatment options, gene therapy has the advantage that is only administered intravenously only once and not weekly. It also has relatively few side effects," explains Cihan Ay, head of the program at MedUni Vienna and University Hospital Vienna, "according to approval studies, over 90% of patients respond well to this therapy and its effect lasts for years."
The Division of Hematology and Hemostaseology at the Department of Medicine I of MedUni Vienna and University Hospital Vienna is currently one of the few centers internationally where this therapy is offered and carried out. This opens up access to this therapy for people with haemophilia in Austria. "It is a great opportunity for those affected by haemophilia B to live a life with less disease burden for years," explains haematologist Cihan Ay. Gene therapy with etranacogene-dezaparvovec is currently approved for the treatment of severe and moderate forms of haemophilia B.