A new type of gene therapy has sharply reduced the risk of bleeding in people with the rare condition haemophilia B.
Researchers found that a single injection of the gene therapy, called FLT180a, removed the need for people to give themselves weekly injections of clotting factors.
The study was led by experts from University College London, the Royal Free Hospital in London and British biotechnology company Freeline Therapeutics.
Haemophilia affects the blood’s ability to clot. It is usually inherited and mostly affects men.
Normally, when a person cuts themselves, clotting factors mix with blood cells called platelets to make the bleeding stop.
But people with haemophilia lack clotting factors, putting them at risk of heavy bleeding.
About 85 per cent of people with the condition have haemophilia A, which is caused by a lack of the blood clotting factor VIII, while haemophilia B is caused by a deficiency of clotting factor IX.
People with haemophilia B need to inject themselves regularly – usually every week – to make up for the deficiency in clotting factor IX, but can continue to incur debilitating joint damage.
In the new 26-week trial, published in the New England Journal of Medicine, experts found that a single treatment with FLT180a led to sustained production of the protein from the liver in nine out of 10 patients with severe or moderately severe haemophilia.
This removed the need for their regular injections and the treatment has long-lasting effects.
“Removing the need for haemophilia patients to regularly inject themselves with the missing protein is an important step in improving their quality of life," said lead author Prof Pratima Chowdary, from University College London.
“The long-term follow-up study will monitor the patients for durability of expression and surveillance for late effects.”
Patients on the trial had to take immune-suppressing drugs over several weeks or several months, to prevent their bodies from rejecting the therapy.
While the treatment was generally well-tolerated by patients, all experienced some side effects.
The patient who received the highest FLT180a dose and had the highest levels of the protein developed an abnormal blood clot.
“Gene therapy is still a young field that pushes the boundaries of science for people with severe genetic diseases," said Freeline co-founder Prof Amit Nathwani, who is also from the university and co-authored the study.
He said the new trial added to “the growing body of evidence that gene therapy has the potential to free patients from the challenges of having to adhere to lifelong therapy or could provide treatment where none exists today".
