Pathbreaking Gene Therapy Successful with X-Linked MTM in 9 Boys

Researchers have used a pathbreaking new gene therapy that had had incredible results in nine boys born with myotubular myopathy (MTM), a rare disease that causes extreme muscle weakness often from birth. Since the gene therapy treatment, all of the boys have better neuromuscular function, most can sit on their own, and four are now breathing without ventilators.

At the American Society of Gene & Cell Therapy (ASGCT), the audience broke out in applause. The gene therapy reduced the first ever results of this kind for this rare disease according to the report. Perry Shieh, neurologist and principal investigator at the University of California, Los Angeles, reports that the boys’ muscle function “have gone from nothing to something.”

The patients in the new study have X-linked MTM, caused by a defect in a gene called MTM1 that encodes an enzyme, myotubularin. Skeletal muscles need the enzyme to develop and function. Boys with the disease have low muscle tone and, in many cases, can barely breathe or move on their own—most require a ventilator and feeding tube. Half of patients die by 18 months, and few live past age 10.

The study was sponsored by Audentes Therapeutics, a gene therapy venture in San Francisco, CA. In this trial, nine boys between 8 and 6 years old with X-linked MTM received an intravenous (IV) infusion of many trillions of particles of a harmless virus, called an adeno-associated virus, reports Science.   In this study, the viruses were designed to carry a good copy of the MTM1 gene, not boy’s muscle cells. Science reported that a free-floating piece of DNA could then trigger the cell’s protein making machinery to produce myotubularin. Three of the patients had three side effects, but that could have been related to the therapy.

About Audentes Therapeutics

Founded in 2013, Audentes Therapeutics is a biotech venture committed to the development and commercialization of innovative new gene therapy treatments for people with serious rare diseases. They have raised $137.5 million since 2013. Audentes Therapeutics teamed with Nationwide Children’s to develop a gene therapy for Duchenne muscular dystrophy as well. Also, in 2013, it received its first $30 million Series A tranche.  For its lead programs, Audentes collaborates with Genethon, Joshua Frase Foundation, myotubular trust, University of Florida, Children’s Hospital and ReGenX as well as Nationwide Children’s. In July 2013, Audentes entered into a license agreement with REGENX Biosciences, LLC for the development and commercialization.