Gene therapy for the treatment of haemophilia B

In a study recently published in the New England Journal of Medicine, 10 men who received gene therapy for haemophilia B now produce the IX factor within normal limits. Hemorrhagic episodes have been reduced from one per month to less than one per year.

The biotech company Spark developed the therapy and carried out the study in collaboration with Pfizer.

The coagulation factor thereby obtained is 8 times stronger than normal and is called factor IX Padua, being discovered in 2009 in an Italian family. The gene is transported to the liver, where the coagulation factor is produced through an inactivated virus – an adeno-associated viral vector.

The earlier studies targeting gene therapy for haemophilia B did not have good outcomes because patients’ immune systems destroyed the altered cells or there was not enough factor. In this study, liver cells were programmed to produce a much more potent version of the factor IX protein, which allowed the use of a lower dose of the viral vector, thus minimizing the immune response.

9 out of 10 men did not register any episode of bleeding and in the only case where the administration of the factor was needed, the dose was reduced by up to 91%.

“The study is small, but very promising and I think that gene therapy for haemophilia B will be at our disposal in a very short time, in a few years. One of the key questions is how long will the effect last? Does it disappear in time? So far, after a year, this doesn’t seem to happen”Aric Parnes, director of the Boston Haemophilia Center, Dana-Farber.


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