A NEW gene therapy for haemophilia has the potential to cure the life-threatening bleeding disorder in one dose, groundbreaking research suggests.
Researchers at the Royal Prince Alfred Hospital in Sydney have called thier findings a major milestone for treating people with the hereditary disorder caused by a defective or missing coagulation factors, which stops their blood from clotting properly.
Patients are dependent on multiple infusions, of up to three times a week, to guard against major bleeding - both internally and externally - that can be triggered by even minor injuries.
But the team of Australian and US researchers have found that, by infusing haemophilia B patients with a gene therapy called factor IX Padua (R338L), their bodies kept expressing the factor IX coagulant on their own. Patients with the haemophilia B subtype have deficient coagulant factor IX.
Their blood was clotting without the need for repeated infusions.
All 10 men with haemophilia B involved in the study developed this response, according to the findings published in the New England Journal of Medicine on Thursday.
Nine of the 10 patients had no bleeds, and eight out of 10 needed no further infusions, the researchers reported after following the men for up to 10 years.
After more than two decades of work, the researchers had discovered "what may be a permanent cure", co-author John Rasko, from RPA, said.
"We now know how to beat the immune response," Professor Rasko, a clinical haematologist and scientist at the University of Sydney, said.
The rate of bleeding the men experienced dropped dramatically from an average of 11.1 bleeds per year to 0.4, reported Professor Rasko and his co-researchers led by haemotology experts at the Children's Hospital of Philadelphia, Pennsylvania.
The researchers reported the treatment was safe and caused no serious side-effects.
"We're very excited about the results, as those people in our trial have previously had to live with the risks of spontaneous bleeding every day," Professor Rasko said.
"To prevent potentially life-threatening bleeds, they have typically had to inject themselves with clotting factors every few days," he said.
About 500 men have the haemophilia B subtype in Australia. About 100 have a severe form of the condition.
Professor Rasko said the research team's next focus would be targeting haemophilia A caused by a defective clotting factor VIII, which affects more than 2300 Australians.
They hoped their work would also further efforts to use gene therapies to treat thousands of other genetic disorders, including blindness and cystic fibrosis.
Mark Lee, one of the men who took part in the trial, had to undergo infusions up to three times a week since birth.
His two brothers died of complications from haemophilia B when they were children. His own two young daughters are carriers for haemophilia.
Since he had the R338L infusion, he has not had a single bleed.
"Now I know that if they have affected children, it will be one injection and they can live normal lives," said Mr Lee, 38.
"This goes beyond our little family ... It will have a positive impact on all generations to come.
"And my mum now knows she won't see her only surviving son die from haemophilia."
Further research is needed to determine the long term efficacy and safety of the treatment.
Biotech company Spark Therapeutics, attached to the Children's Hospital of Philadelphia is funding the commercialisation of the therapy.
The trial was funded by Spark Therapeutics and Pfizer.
Director of the NSW Office of Health and Medical research Tony Penna said the breakthrough findings, which had the potential to save thousands of lives worldwide, was possible because of the dedication of the researchers and NSW's cutting-edge gene and cell therapy facilities.
"This is a world-first that all Australians can be proud of and highlight the need for both public and private investment in medical research," Dr Penna said.
