Time – Patients with hemophilia need to receive infusions of FIX two to three times per week in order to prevent them from bleeding spontaneously or bleeding too much from even slight cuts and wounds — a potentially fatal condition. But in the new study, four of the six patients who received gene therapy were able to make FIX on their own, enough to stop their regular treatments. The other two patients also benefited: they weren’t able to abandon their infusions altogether, but they didn’t need as many sessions as before the gene therapy.
Led by Amit Nathwani at University College London, scientists introduced the working gene for FIX to patients by injecting them with cold viruses that were engineered to carry the gene in, infect cells, and start producing the needed clotting protein. This is the standard technique used in gene therapy, but often it fails because the immune system kills off the cold viruses before they can do their work.
Nathwani’s team was able to figure out a more efficient way to install the new genes. At the start of the study, all of the participants had less than 1% of normal levels of FIX in their blood. By the end of the study, which followed patients for as long as six to 16 months, most had FIX levels that were 3% to 11% of normal values. Two patients each received low, intermediate or high doses of the gene therapy in an IV-like infusion in the arm.
Haemophilia is rare, with only about 1 instance in every 10,000 births (or 1 in 5,000 male births) for haemophilia A and 1 in 50,000 births for haemophilia B. About 18,000 people in the United States have haemophilia. Each year in the US, about 400 babies are born with the disorder. Haemophilia usually occurs in males and less often in females. It is estimated that about 2500 Canadians have haemophilia A, and about 500 Canadians have haemophilia B