By Maureen Salamon
WEDNESDAY, Dec. 6, 2017 (HealthDay News) – Gene therapy has helped 10 men with a form of the bleeding disorder to produce hemophilia as a blood clotting factor. critical blood. This could eliminate the need for tedious and expensive standard treatments, the researchers report.
Although they said that unique gene therapy was an ideal treatment target because of its effects, researchers did not call it a cure for hemophilia B since it is not clear if the benefits will be permanent.
In addition, experts said that early-stage research should be replicated in larger trials.
But experimental gene therapy produced "a truly dramatic life change" for the men in the study, said the study's lead author, Dr. Lindsey George, a hematologist at Children's Hospital of Philadelphia.
"He really freed these men to live a normal life," George said. "It meant they could wake up and go on with their day and not live in fear of having bleeding episodes."
Hemophilia arises from an inherited genetic mutation that impedes the ability to produce normal levels of a blood coagulation factor. This leaves patients vulnerable to spontaneous bleeding or excessive bleeding from injuries. The disorder has two main forms: hemophilia A, which affects approximately 80 percent of all patients, and hemophilia B.
Hemophilia B occurs in about 1 in 30,000 children and men, George said. Because the recessive gene disorder is related to the X chromosome, women can be carriers but are not affected by the condition. Standard treatment involves weekly infusions of a coagulation factor manufactured to prevent bleeding problems.
The new research was funded by the pharmaceutical companies Spark Therapeutics and Pfizer.
For the study, George and his colleagues administered a dose of gene therapy each in 10 livers of patients with hemophilia B This is where the body normally produces the protein called factor IX that allows blood to clot properly.
The dose contained a "genetically modified payload" of the gene encoding a natural coagulation factor that is eight to 10 times stronger than the normal factor and known as factor IX-Padua.
All patients benefited from gene therapy, the researchers said. He removed them from the category of serious illness and almost eliminated the bleeding in his joints, a persistent previous problem.
Eight of the 10 did not require any additional standard treatment, and 9 of the 10 did not experience bleeding problems after treatment. gene therapy. None experienced serious complications, according to the study.
The research was published on December 7 in New England Journal of Medicine .
"What is transformative about this [study] is that they converted people who were at risk of having these bleeds and now have coagulation factor levels where they can do pretty much everything they want," said Dr. Matthew Porteus He is an associate professor of pediatrics – stem cell transplantation at the Stanford University School of Medicine.
"Patients can really live essentially normal lives, even playing sports like football, which now discourages patients with hemophilia," he added. Porteus, who wrote an editorial that accompanies the study.
"But this is a study on 10 patients and now the challenge is to expand it to many more," he said.
Another obstacle is that approximately one third of patients with hemophilia B have a pre-existing immunity to the virus that administers this type of gene therapy, which makes them ineligible to receive it, George and Porteus noted.
Researchers are also trying to develop a similar gene therapy for hemophilia A, which has proved to be more challenging.
The potential price of gene therapy with hemophilia B is a problem, but George and Porteus said it could be compensated by eliminating the need for standard treatments. These can cost between $ 100,000 and $ 500,000 per year.
Only two genetic therapies are approved for use in the United States, both for blood cancers. And "less than a handful" are in use around the world, said Porteus. Typically they cost between $ 400,000 and $ 1 million for each therapy.
"That obviously raised some eyebrows and gave some people a publicity shock," he added.
"But even from $ 800,000 to $ 1 million, that could end up being expensive" Effective during the life of a patient. That said, how to price and reimburse gene therapies is an active area of discussion and there is no real consensus, "said Porteus.