Researchers Seek Participants for CMS Trial

Researchers are looking for children and adults with congenital myasthenic syndrome (CMS) to participate in a phase 3 study being conducted by Catalyst Pharmaceuticals to test the experimental drug amifampridine phosphate (brand name Firdapse).

Amifampridine phosphate is a potassium channel inhibitor designed to cause greater stimulation of muscle by prolonging nerve signals and is expected to help treat muscle weakness in people with CMS. The drug has shown promising results in treating patients with a related disorder called LEMS.

The goals of the study are to determine the safety, tolerability and efficacy of amifampridine phosphate and determine whether the drug is effective in CMS.

Study participants will receive an initial evaluation and several clinical exams. Tests will include heart rhythm (ECG), muscle testing (EMG) and questionnaires. Expected length of participation time is 56 days. After study completion, participants will be eligible for an expanded access program in which they will be able to continue to receive treatment with the drug.

Participants may be male or female, age 2 years or older, with a genetically confirmed CMS mutation. Those whose CMS has not been genetically confirmed will have genetic testing done at screening, and additional eligibility criteria will be reviewed with each patient’s physician.

Trial sites are located in California, Georgia, Maryland, Massachusetts and Ohio. Travel-related costs will be provided for those who are willing to travel.

For additional information on this trial, visit and enter NCT02562066 in the “Other Terms” search box. There you can find contact information for the trial coordinator at each study site. You can also visit Catalyst’s website: If you are interested in participating in the study, call 844-347-3277 or email

MDA has supported the development of amifampridine phosphate for children with CMS. It’s hoped that this trial will yield insight into whether or not the drug may be an effective treatment.