Below is a wrap-up of recent research news about the development of therapies for Duchenne, Becker and limb-girdle muscular dystrophies.
Follistatin compound gains orphan drug status
A potentially therapeutic construct that combines the gene for the follistatin protein with the shell of an AAV1 virus as a delivery vehicle has been granted orphan drug designation by the U.S. Food and Drug Administration (FDA) for the treatment of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD).
Orphan drug designation is a mechanism the FDA uses to encourage development of treatment for rare disorders. It qualifies the developer of the experimental drug for a tax credit and other financial incentives. However, it does not alter the requirements for safety and efficacy that a compound must meet for approval. Milo Biotechnology, a Cleveland-based company, announced the designation December 12, 2012.
Follistatin gene transfer, which may help build muscle size and strength, is now being tested in a clinical trial in people with BMD and sporadic inclusion-body myositis (IBM).
To learn more, see: Milo Biotechnology Announces FDA Orphan Drug Designation for AAV1-FS344 for Treatment of Duchenne and Becker Muscular Dystrophy and Follistatin Gene Transfer to Patients with Becker Muscular Dystrophy and Sporadic Inclusion-Body Myositis (description of a clinical trial of follistatin gene transfer, which is enrolling participants by invitation only).
Building better utrophin
Scientists funded in part by Muscular Dystrophy Association (MDA) have modified the gene for the utrophin protein, potentially making utrophin supplementation a more effective therapy for DMD or BMD, two disorders that result from a deficiency of the dystrophin protein.
Dongsheng Duan, an MDA grantee at the University of Missouri, Columbia, and colleagues, changed the utrophin gene so that a protein that helps regulate blood flow to exercising muscles can stick to it the same way it does to the dystrophin protein. When mice missing both utrophin and dystrophin were given gene therapy using the new, modified utrophin genes, the blood-flow protein known as nNOS was properly located in muscle fibers.
To learn more, see: Alpha 2 and Alpha 3 Helices of Dystrophin R16 and R17 Frame a Microdomain in the Alpha 1 Helix of Dystrophin R17 for Neuronal NOS Binding and Another Muscular Dystrophy Mystery Solved; MU Scientists Inch Closer to a Therapy for Patients.
Dantrolene enhances exon skipping
The prescription drug dantrolene has been found to have an unexpected benefit— it appears to enhance the effectiveness of the experimental, gene-altering therapy known as exon skipping in a mouse model of DMD and in cells taken from patients with the disorder.
Dantrolene is used to treat chronic spasticity and an adverse anesthesia reaction known as malignant hyperthermia. When given along with an exon-skipping therapy to DMD mice, it improved exon skipping, resulting in additional production of the needed dystrophin protein and allowing the dantrolene-treated mice to hang on a wire for 50 percent longer than those treated with exon skipping alone.
To learn more, see: Dantrolene Enhances Antisense-Mediated Exon Skipping in Human and Mouse Models of Duchenne Muscular Dystrophy; A Genetic Intervention Stands a Skip Away from Clinical Tests and Scientists Find Drug That May Help in Fight Against Duchenne Muscular Dystrophy.
Written by Margaret Wahl. Read more at Quest: MDA’s Research & Health Magazine.