The team, led by University College London’s (UCL) Edward Tuddenham, reprogrammed adenovirus-associated virus eight (AAV8) to deliver a gene that encodes the healthy version of blood clotting protein factor IX to hepatocytes.
After infusion into the veins of six haemophiliac volunteers, the virus entered the liver cells where its DNA payload was uncoated and transferred to the nucleus where it started to direct synthesis of factor IX mRNA.
Four of the six patients have been able to discontinue use of their medication, FIX prophylaxis, whilst the other two require less frequent injections. And the team say the only abnormalities the patients will now suffer would be in the case of severe major trauma.
In the study, lead author Amit Nathwani, also of UCL, wrote that the approach “has the potential to convert the severe bleeding phenotype into a mild form of the disease or to reverse it entirely.”
However, though the results of the combined Phase 1 & 2 trial – published in the New England Journal of Medicine – seem promising, professorial research associate at UCL’s Cancer Institute Tuddenham told in-PharmaTechnologist that further work must be done over the next decade.
He said: “Over the next decade or two gene therapy could take over as the preferred treatment in adults.
“Further developments are needed to make it feasible in children since the fact AAV is non-integrating means a child treated at age 3 would need repeat treatment at least twice during growth, which could not be with the same serotype of AAV.”
A genetic cure-all?
Tuddenham also told us that the platform has potential in treating all single gene protein deficiency genetic diseases.
“The most obvious ones affect proteins made in the liver of which there are about 100 known defects,” he said.
“Other tissues can be targeted with other naturally occurring AAAV vectors or specifically engineered variants with any desired tissue tropism, opening the way for treatment of most genetic diseases.”
He added that certain acquired disorders are also potential targets, such as liver cancer.