The thirteen patients were given the gene therapy at Barts Health NHS Trust, in the U.K. Eleven of the patients are now producing normal levels of the protein that was previously missing from their blood. The lead researcher of the trial, Professor John Pasi, who told the BBC: “This is huge. It’s ground-breaking because the option to think about normalising levels in patients with severe hemophilia is absolutely mind-blowing.”
The medic added: “To offer people the potential of a normal life when they’ve had to inject themselves with factor VIII every other day to prevent bleeding is transformational.”
Hemophilia
Hemophilia is a rare condition that affects the blood’s ability to clot. The condition is usually inherited, and most people who have the genetic disease are male. With people without the condition (the majority of the population), when someone cuts themselves substances in the blood known (clotting factors) combine with blood platelets to make the blood sticky and stop the bleeding. For people with hemophilia this doesn’t happen, leading to risk of injury or death.
Hemophilia A (also known as Classic Hemophilia or Factor VIII deficiency) is the most well-known type of clotting disorder. Here the specific coagulation factor that is missing or reduced in people with Hemophilia A is Factor VIII. There is currently no cure and treatment is given by clotting factors are either preventively or on-demand. Clotting factors are either manufactured from donated human plasma or by recombinant technology.
Gene therapy
With the new study, this was based on gene therapy. This is the therapeutic delivery of nucleic acid into a patient’s cells as a drug to treat disease. Gene therapy is a way to fix a genetic problem at its source, involving replacing a mutated gene that causes disease with a healthy copy of the gene; or inactivating, or “knocking out,” a mutated gene that is functioning improperly; or introducing a new gene into the body to help fight a disease. The new study involved medics infusing a single intravenous dose of a codon-optimized adeno-associated virus serotype 5 (AAV5) vector, desiged to encode a B-domain–deleted human factor VIII (AAV5-hFVIII-SQ).
While the results were successful, there was a wide variation in who responded to therapy and further study is required. Nonetheless, the results could be the first step towards a cure for hemophilia.
The results of the trial have been published in the New England Journal of Medicine. The research paper is titled “AAV5–Factor VIII Gene Transfer in Severe Hemophilia A.”
