Researchers at UMass Chan Medical School and Auburn University have developed the first-ever gene therapy for Tay-Sachs disease.
After fourteen years of development, gene therapy for Tay-Sachs disease has begun phase I/II trial. As part of the trial, two babies have already received the ground-breaking treatment. Previously, gene therapy has helped treat vision problems and even chronic pain. However, this is the first-ever gene therapy to enter clinical trials for Tay-Sachs disease.
Tay-Sachs is a lysosomal storage disease caused by an absence of the enzyme, HexA. This particular enzyme helps break down the fatty substance GM2 ganglioside within the brain. However, deficiency of the enzyme causes a buildup of the fatty substance to toxic levels; thus, damaging nerve cells in the brain and spinal cord. As a result, affected infants present with muscle weakness, vision loss, seizures, hearing loss, problems swallowing and loss of mental functions. Children survive only a few years with most death occurring by age 5.
The disease has no cure; therefore, doctors prescribe aggressive medical treatment to slow disease progression. Moreover, attempts at replacing the missing enzyme have not been successful due to the presence of the blood-brain barrier preventing large molecules from entering the brain. Now, researchers at UMass Chan Medical School have developed a gene therapy that can go around this barrier. Labelled AXO-AAV-GM2, the treatment uses viral vectors to deliver DNA instructions to brain cells. Thus, relaying instructions to produce the missing enzyme characteristic of Tay-Sachs. Children are given the treatment directly to the brain and spinal cord.
We share their hope that this treatment can halt or reverse the otherwise inexorable course of these tragic diseases.
Dr. Terence R. Flotte, principal trial investigator
Children Remain Seizure-Free
One of the children received gene therapy at the age of 2.5 years and was initially suffering from late-stage disease symptoms. However, doctors started noticing increased muscle control after just three months of treatment. Now, years later at the age of 5, the child has remained seizure-free and is in a stable condition.
The second child part of the trial received the treatment at 7 months of age. Similar to the previous case, doctors reported improved brain development after three months of treatment. Moreover, at the age of 2, the child has now remained seizure-free.
Despite the successful results, further research is required into the long-term effects of the treatment. And whether it can completely halt disease progression. The team of researchers are currently conducting a follow-up clinical trial to test the safety and efficacy of a higher dose in a larger sample size.
Reference:
Flotte, T.R., Cataltepe, O., Puri, A. et al. AAV gene therapy for Tay-Sachs disease. Nat Med 28, 251–259 (2022). https://doi.org/10.1038/s41591-021-01664-4
