Myo-029 is safe but does not increase muscle strength

The results of a phase I/II trial to test the safety and tolerability of Myo-029 were published last week in the scientific journal Annals of Neurology by Dr Karthryn R. Wagner from John Hopkins University School of Medicine in Baltimore, US and colleagues.

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What is Myo-029?

Myo-029 is an antibody that blocks the activity of myostatin, a muscle protein that acts to inhibit muscle strength. Myostatin was therefore considered as a target for the development of treatments for adults with muscular dystrophy. It was hoped that by blocking its activity the muscles would become larger and increase in strength.

What are the results?

The multinational phase I/II clinical trial included patients with Becker muscular dystrophy, facioscapulohumeral muscular dystrophy and limb girdle muscular dystrophy. The report states that Myo-029 shows no side effects at all three dosages tested and was safe and well tolerated in these types of muscular dystrophies. There was, however, no increase or improvement in muscle strength or function over the length of the trial, although the authors mention that the trial was designed to only investigate safety. The number of patients in each group was considered too small to detect any significant differences.

The researchers state that the results of the clinical trial support the hypothesis that systemic administration of myostatin inhibitors is safe and that further evaluation of more potent myostatin inhibitors should be considered.

Statement from Wyeth Pharmaceuticals

The company that initiated the trial in 2005, Wyeth Pharmaceuticals of Madison, US, announced last week that it will not continue with further development Myo-029 for muscle disease.

“The decision to discontinue development of Myo-029 was a difficult one that was appropriate based on the evidence from our studies,” Gary L. Stiles, M.D., Executive Vice President and Chief Medical Officer at Wyeth Pharmaceuticals.

“Wyeth remains committed to discovering and developing treatments for muscle diseases and continues to explore myostatin inhibition along with other strategies.”


Statement from Dr Marita Pohlschmidt, Director of Research at the Muscular Dystrophy Campaign

Dr Marita Pohlschmidt, Director of Research at the Muscular Dystrophy Campaign said: “Although the results of the trial are disappointing, we are pleased to hear that Wyeth will continue to invest into other promising compounds directed at inhibiting myostatin activity. Myostatin as a target has great potential for developing a treatment and I hope that research will continue in this direction.”

Further information about Myo-029 can be found in the original paper. Please go to www3.interscience.wiley.com