Proof of Concept Data Highlights Viability of Gene Therapy for Metachromatic Leukodystrophy

According to a story from Market Screener, the genetic medicines company Homology Medicines, Inc., recently announced the presentation of data which revealed that the company’s proprietary virus vectors, which are common delivery mechanisms for gene therapies, are capable of crossing the blood-brain barrier. This will allow them to be a possible treatment for the rare disorder metachromatic leukodystrophy.

About Metachromatic Leukodystrophy

Metachromatic leukodystrophy is a type of lysosomal storage disease which is characterized by the buildup of cerebroside sulfate. This is caused by a deficiency in the metabolism of sphingolipids. Leukodystrophies affect the development of the myelin sheath, an insulating fatty layer that coats nerve cells and plays a critical role in normal nerve function and communication. The disease is caused by a mutation which in turn leads to a deficiency of the ARSA enzyme. Symptoms vary depending on when onset of disease begins. In the most common infantile form, symptoms include difficulty walking, muscle atrophy, weakness, and stiffness, trouble swallowing, dementia, loss of vision, and convulsions. In later onset forms, disease progression is much slower and is most characterized by dementia. Treatment is mostly symptomatic; gene therapy, enzyme replacement, and other therapies are in clinical trials. Stem cell transplant can be useful in some cases. Most patients die before age five. To learn more about metachromatic leukodystrophy, click here.

Homology’s Data

The data showed that Homology’s vectors were able to traverse a number of nervous system cells and tissues without issue following intravenous injection. The metachromatic leukodystrophy model also indicated encouraging results regarding the therapy’s potential effectiveness. Administration led to 30 to 115 percent of ARSA enzyme activity, which well exceeded the target percentage of 10-15. The company has yet to announce its gene therapy candidate, but it is expected to do so before the end of the year. Early studies will soon follow in 2019.

The Blood-Brain Barrier

Many drugs are not able to pass the blood-brain barrier, which impacts their ability to address the cognitive effects of disease. Having this ability will be essential to any therapy for metachromatic leukodystrophy that has any chance of being completely effective, and dementia is one of the most common and defining symptoms of the disease.

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