Trial of Antisense Drug for Type 1 Myotonic Dystrophy Opens

Isis Pharmaceuticals has announced the opening of a U.S. trial to evaluate the safety and tolerability of ISIS-DMPKRx in adults with type 1 myotonic dystrophy

Article Highlights:
  • ISIS-DMPKRx is an "antisense"-based compound in development by Isis Pharmaceuticals and Biogen Idec to target and reduce toxic RNA levels in cells in type 1 myotonic dystrophy patients.
  • MDA, while not supporting this trial directly, has supported the foundational research that has contributed to understanding the molecular underpinnings of myotonic dystrophy and antisense strategies to treat this disease.
  • The trial is slated to include 36 adults with type 1 myotonic dystrophy at seven U.S. centers.
by Margaret Wahl on December 22, 2014 - 5:12pm

A phase 1-2 trial of ISIS-DMPKRx, an experimental compound for the treatment of type 1 myotonic muscular dystrophy, is now underway in the U.S. in adults with this disorder who are 20 to 55 years old and meet other study criteria. Isis Pharmaceuticals of Carlsbad, Calif., which is developing the drug in collaboration with Biogen Idec of Cambridge, Mass.,  announced the opening of the new trial in a Dec. 16, 2014, press release.

ISIS-DMPKRx targets toxic genetic material

ISIS-DMPKRx is an "antisense" compound and is designed to reduce levels of toxic genetic material (RNA, made from DNA) from the DMPK gene. This toxic RNA, produced because of a mutation in the DMPK gene inside muscle and other cells, is the molecular cause of type 1 myotonic dystrophy. MDA has supported much of the foundational research that led to understanding this phenomenon in myotonic dystrophy and developing antisense-based and other strategies to counteract its effects.

"Myotonic dystrophy represents an ideal oportunity for antisense, as the disease-causing gene produces a toxic RNA, which accumulates within cells, including muscle, and is not accessible by traditional therapeutic approaches," said Frank Bennett, senior vice president of research at Isis. "ISIS-DMPKRx has the potential to address the underlying genetic defect that causes DM1 [type 1 myotonic dystrophy]. This study is important, as it is the first study in which we will be observing the effects of our drug in patients with myotonic dystrophy, and it is the first study in which we are targeting a toxic RNA."

About the phase 1-2 ISIS-DMPKRx trial

The phase 1-2 trial of ISIS-DMPKRx in type 1 myotonic dystrophy patients will enroll approximately 36 adults who will be randomly assigned to receive subcutaneous (under the skin) injections of the drug or a placebo for six weeks. Participants in the DMPKRx group will receive multiple injections of the drug at a specific dose, with different groups receiving different doses, to help establish the safety and tolerability of ISIS-DMPKRx.

Study sites are in Stanford, Calif.; Gainesville, Fla.; Kansas City, Kan.; Baltimore, Md.; and Salt Lake City, Utah. As of Dec. 10, 2014, only the Salt Lake City site was open to recruitment.

Participants must:

  • have a genetically confirmed diagnosis of type 1 myotonic dystrophy, with at least 100 "CTG repeats" in the DMPK gene;
  • be 20-55 years old;
  • have experienced symptom onset after age 12;
  • have myotonia (difficulty relaxing muscles);
  • be able to walk at least 25 meters (82 feet) without a cane or walker at screening; and
  • meet other study criteria.

Participants must not:

  • have significant abnormalities in their medical history or screening laboratory tests;
  • have a recent history of drug or alcohol abuse;
  • have a history of bleeding tendency or be on drugs that interfere with blood clotting; or
  • have developmental delay, intellectual disability or significant behavioral abnormalities.

 Note: This is not a complete list of study criteria.

To participate

For details and contact information, see A Safety and Tolerability Study of Multiple Doses of ISIS-DMPKRx in Adults With Myotonic Dystrophy Type 1; or enter NCT02312011 in the search box at

You can also contact Isis Pharmaceuticals at (800) 679-4747 or



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