Researchers at Nationwide Children’s Hospital (Ohio, USA) have published the results of their gene therapy trial for limb girdle muscular dystrophy type 2D (LGMD2D). This was a phase I, open-label study testing a potential new treatment called MYO-102.
The therapy aims to deliver alpha-sarcoglycan – the gene that is faulty in LGMD2D – into muscles. This is achieved by packaging the gene into a carrier called a vector. MYO-102 uses an adeno-associated virus (AAV) vector. This has the ability to infect human cells and deliver the gene without causing disease.
In this trial, MYO-102 was administered to patients using a method called isolated limb infusion. This is where the flow of blood to and from the limb is temporarily stopped with a very tight band. The treatment is then pumped into the limb using a thin tube connected to a blood vessel.
The researchers chose this delivery method because it keeps the gene therapy within the limb. They thought that this would be safer than delivering it systemically (to the entire body).
Six patients with LGMD2D took part in the study. Initially, a non-ambulant adult received the gene therapy in one leg. Once the investigators confirmed that the treatment was safe, five ambulatory children went on to receive the drug in both legs. They were followed up for a total of two years.
Following treatment, four of the children had increased levels of alpha-sarcoglycan protein in their muscles. Two children had changes in their thigh muscle strength but unfortunately, the results from the six minute walk test worsened or remained the same in all participants. According to the researchers, to see an improvement in walking ability, the gene therapy would need to reach a wider set of muscles.
Based on these results, the researchers concluded that isolated limb infusion is not an adequate method of delivery for MYO-102. The next step will be a clinical trial testing systemic administration of the therapy. This is expected to begin in early 2020.
MYO-102 is one of the five LGMD gene therapies being developed by Myonexus Therapeutics. In February, Sarepta Therapeutics announced its intention to buy out Myonexus and continue the development of these important treatments.
The study was published in the journal Human Gene Therapy.
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