Stories about: myotubular myopathy

New hope for X-linked myotubular myopathy as gene therapy clinical trial begins

gene therapy myotubular myopathy

Boys born with X-linked myotubular myopathy (XLMTM) face a grim prognosis. Extreme muscle weakness leaves many ventilator-dependent from birth, and most infants need feeding tubes. About half pass away before 18 months of age.

Last week, the biotechnology company Audentes Therapeutics announced the dosing of the first patient in a gene-therapy clinical trial — 21 years after the MTM1 gene was first cloned.

Hopes are high. Gene therapy has already shown striking benefits in dogs with XLMTM in studies co-authored by Alan Beggs, PhD, director of the Manton Center for Orphan Disease Research at Boston Children’s Hospital, and colleagues at Généthon and the University of Washington. In the most recent study, 10-week-old Labrador retrievers already showing signs of the disease showed improvements in breathing, limb strength and walking gait after a single dose of the gene therapy vector.

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A gene therapy advance for muscle-wasting myotubular myopathy

X-linked myotubular myopathy XLMTM gene therapy
Nibs, a carrier of MTM whose descendants provided the basis for the gene therapy study. (Read more of her story.)

For more than two decades, Alan Beggs, PhD, at Boston Children’s Hospital has explored the genetic causes of congenital myopathies, disorders that weaken children’s muscles, and investigated how the mutations lead to muscle weakness. For one life-threatening disorder, X-linked myotubular myopathy (XLMTM), the work is approaching potential payoff, in the form of a clinical gene therapy trial.

Boys with XLMTM are born so weak that they are dependent on ventilators and feeding tubes to survive. Almost half die before 18 months of age.

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Gene therapy strengthens weak muscles in congenital myopathy

Alison Frase with Nibs, a carrier of MTM whose descendants provided the basis for the gene therapy study.
Alison Frase with Nibs, a carrier of MTM whose descendants provided the basis for the gene therapy study.

Babies born with X-linked myotubular myopathy (MTM), which affects about one in 50,000 male births, are commonly referred to as “floppy.” They have very weak skeletal muscles, making it difficult to walk or breathe; survival requires intensive support, often including tube feeding and mechanical ventilation. Most children with MTM never reach adulthood.

One of these children, Joshua Frase, succumbed to MTM on Christmas Eve, 2010. The son of former NFL player Paul Frase, he lived to age 15. But his parents, who continue to actively support MTM research, now see a glimmer of hope for children born with the disease today.

A preclinical study on the cover of last week’s Science Translational Medicine, funded in part by the Joshua Frase Foundation, showed dramatic improvements in muscle strength using gene replacement therapy in mouse and dog models of MTM—paving the way for a potential clinical trial.

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Restoring muscle function in a rare, devastating disease: Part 2

Joshua Frase, who died from X-linked MTM, with his father in 2006.

Part 2 of a two-part series. (Read part 1.)

Back in the 1990s, rheumatologist Richard Weisbart, MD, of University of California, Los Angeles (UCLA), was studying lupus in a mouse model and found that the mice were making an antibody that had the intriguing ability to get inside tissues and cells.

Weisbart shifted his work away from studying lupus to studying and refining the antibody, called 3E10, and he and others showed that proteins could be delivered into different tissues of the body simply by attaching them to a fragment of 3E10.

Dustin Armstrong, PhD, a postdoc at Novartis at the time, was trying to find molecules that could activate growth in weakened muscles—without activating possibly cancerous growth in other tissues. He saw Weisbart’s work and contacted UCLA. In 2008, he obtained seed money and founded a company around 3E10-based therapeutics for muscular diseases, now known as Valerion Therapeutics (formerly 4s3 Bioscience).

“There’s a huge need for therapies for genetic muscle diseases, and muscle was a tissue we could target well with our technology,” says Armstrong.

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Restoring muscle function in a rare, devastating disease: Part 1

Will Ward at the NSTAR Walk for Boston Children’s Hospital in 2012.

This two-part series examines two potential treatment approaches for myotubular myopathy, a genetic disorder that causes muscle weakness from birth.

Sixth-grader William Ward cruises the hallways at school with a thumb-driven power chair and participates in class with the help of a DynaVox speech device. Although born with a rare, muscle-weakening disease called X-linked myotubular myopathy, or MTM, leaving him virtually immobile, he hasn’t given up.

Neither has Alan Beggs, PhD, who directs the Manton Center for Orphan Disease Research at Boston Children’s Hospital, and who has known Will since he was a newborn in intensive care.

“From the very beginning, Alan connected with our family in a very human way,” says Will’s mother, Erin Ward. “In the scientific community, he’s been the bridge and the connector of researchers around the world. That makes him unique.”

Since the 1990s, Beggs has enrolled more than 500 patients with congenital myopathies from all over the world in genetic studies, seeking causes and potential treatments for congenital myopathies—rare, often fatal diseases that weaken children’s skeletal muscles from birth, often requiring them to breathe on a ventilator and to receive food through a gastrostomy tube.

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