MMD1: Antisense Drug Moves to Human Testing

Isis Pharmaceuticals is launching a phase 1 trial of ISIS-DMPKRx, an experimental drug for type 1 myotonic muscular dystrophy

Article Highlights:
  • ISIS-DMPKRx is an experimental drug for type 1 myotonic muscular dystrophy (MMD1 or DM1) based on antisense technology, a strategy to block disease-causing genetic instructions.
  • MDA has funded multiple studies to understand the underlying causes of MMD1 and to conduct laboratory experiments to test antisense strategies for this disorder.
  • A phase 1 trial of ISIS-DMPKRx is being launched; details are expected soon.
by Margaret Wahl on June 10, 2014 - 8:30am


Update (June 11, 2014): This story has been updated with additional information about the phase 1 trial of ISIS-DMPKRx in healthy volunteers and the planned trial in people with type 1 MMD, as well as the availability of a fact sheet on this drug provided by Isis Pharmaceuticals.


An experimental drug that targets the root cause of type 1 myotonic muscular dystrophy (MMD or DM) will now be tested in a phase 1 clinical trial in healthy volunteers, says the drug’s developer, Isis Pharmaceuticals, of Carlsbad, Calif.

Isis, which is collaborating with Cambridge, Mass.-based Biogen Idec, announced the launch of the phase 1 trial to evaluate the safety of the investigational drug -- known as ISIS-DMPKRx -- in a June 9, 2014, press release. A trial of the drug in people with type 1 MMD is expected to start in late 2014, and details will be posted on and as soon as they become available.

“ISIS-DMPKRx is an example of the broad applicability of our … technology to develop novel drugs to treat patients with severe and rare diseases,” said C. Frank Bennett, senior vice president of research at Isis. He added that “myotonic dystrophy represents an ideal opportunity” for Isis’ technology, because the underlying abnormality in this disorder has not been treatable with traditional approaches but should be treatable with the type of molecular approach Isis is taking.

New drug targets toxic web using ‘antisense’

Type 1 myotonic dystrophy (MMD1 or DM1) is a genetic, multisystem disorder that causes weakness of voluntary muscles and difficulty relaxing muscles (“myotonia”), as well as abnormalities of the heart, gastrointestinal tract, eyes and brain.

The genetic cause of MMD1, which was identified with MDA support in 1992, is an abnormal expansion in a gene on chromosome 19 that codes for a protein known as DMPK. Since then, and also with substantial funding from MDA, biologists have learned that the molecular root of the disease is the presence of expanded DMPK genetic instructions (strands of RNA) that trap important cellular proteins the way a spider’s web traps insects.

Blocking the abnormal RNA expansions so that they can’t interact with and disable cellular proteins is the goal of treatment with ISIS-DMPKRx. For details, see Myotonic Dystrophy Type 1 & ISIS-DMPKRx, a fact sheet provided by Isis Pharmaceuticals.

The drug was developed using antisense technology, which specifically targets and then blocks or destroys harmful genetic instructions.

MDA helped develop promising technology

MDA has played a major role in developing antisense-based therapy for MMD, particularly via research grants to Charles Thornton at the University of Rochester (N.Y.), Thomas Cooper at Baylor College of Medicine in Houston, and Matthew Disney at the Scripps Research Institute in Jupiter, Fla.

“This is a big step forward for the myotonic dystrophy community,” said neurologist Valerie Cwik, MDA’s chief medical and scientific officer. “MDA has long supported and continues to support antisense-based technology, a highly promising strategy for disorders in which blocking flawed genetic instructions has the potential to save and improve lives.”

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