Insmed Incorporated, the University of Rochester School of Medicine and the Muscular Dystrophy Association (MDA) have initiated a Phase 2 clinical study investigating the use of iPlex (mecasermin rinfabate (rDNA origin) injection), a once-daily IGF-1 therapy, for the treatment of myotonic muscular dystrophy (MMD), the most common form of adult muscular dystrophy.

iPlex is a proprietary drug product for the delivery of recombinant insulin-like growth factor 1 (IGF-1). It is administered as a preformed complex with a recombinant form of its natural binding protein, insulin-like growth factor binding protein 3 (rhIGFBP-3). The novel compound is administered as a once-daily subcutaneous injection, which can restore and maintain IGF-1 levels to physiologically relevant levels. (The original name of the Insmed compound was SomatoKine.)

It has been known for decades that MMD patients do not respond normally to insulin. Recent research has identified an abnormality in an insulin receptor protein as the underlying cause and IGF-1 as a potential remedy.

Myotonic muscular dystrophy (also known as myotonic dystrophy, dystrophia myotonica or Steinert's disease, and abbreviated MMD, MyD, or DM) is the most common type of adult muscular dystrophy, which affects 1 in 8000 individuals (approximately 40,000 people in the United States). It causes progressive muscle wasting and weakness in the hands, forearms, legs, neck and face. It often involves many other systemic effects, including endocrine abnormalities, especially with respect to insulin, a regulator of blood sugar (glucose); neurological changes, including excessive sleepiness and apathy; cataracts, usually requiring surgical excision; gastrointestinal problems; and cardiac rhythm abnormalities, often requiring pacemaker insertion.

The disease can lead to severe disability, and death can result from respiratory muscle weakness or fatal cardiac dysrhythmias. At present, there is no treatment to reverse the muscle weakness or wasting or the defective insulin utilization in MMD.

"For decades we have studied various potential therapies for patients afflicted with myotonic dystrophy," stated Richard T. Moxley, Professor of Neurology and Paediatrics at the University of Rochester and the Principal Investigator in the Phase II trial. "This study is based on preliminary clinical data demonstrating IGF-1's ability to restore or preserve muscle strength as well as improve glucose control. We are optimistic that iPlex given once daily will be effective and well tolerated in these patients," he added.

Kenneth M. Attie, chief medical officer of Insmed, said, "Myotonic dystrophy is an example of a serious disease, characterized by muscle wasting and insulin resistance, for which iPlex may be an ideal therapeutic intervention. We are very pleased that NIH has endorsed Dr. Moxley's protocol and that NIH and MDA are supporting this important clinical trial. Insmed is committed to working with the University of Rochester to advance the study of iPlex for this devastating disease."