Trial to Test Firdapse in MG Seeks Participants

Researchers are looking for people with myasthenia gravis (MG) to participate in a phase 3 clinical trial to evaluate the safety and effectiveness of the investigational drug amifampridine phosphate (brand name Firdapse). Effects of the drug will be assessed in individuals with muscle-specific kinase (MuSK) antibody positive MG and in a smaller group with acetylcholine receptor (AChR) antibody positive MG.

Amifampridine phosphate, under development by Catalyst Pharmaceuticals, is a potassium channel inhibitor designed to prolong signals released from nerves and allow greater stimulation of muscles. The drug currently is under clinical investigation as a symptomatic therapy to treat muscle weakness in people with MuSK-antibody positive myasthenia gravis. It also has shown promising results in a phase 3 trial to test it in people with Lambert-Eaton myasthenic syndrome (LEMS), and currently is under investigation as a treatment for children and adults with congenital myasthenic syndrome (CMS).

Amifampridine phosphate received Orphan Drug designation for treatment of MG from the U.S. Food and Drug Administration (FDA) in September 2016.

Trial length is approximately 38 days, during which participants will visit with study investigators four to six times. At study visits, participants will undergo EKG testing and treatment effects will be measured across two MG-specific assessment scales: the Quantitative Myasthenia Gravis (QMG) and the Myasthenia Gravis – Activities of Daily Living profile (MG-ADL).

In order to be eligible to participate, individuals must:

  • be at least 18 years old
  • have a diagnosis of MG with positive serologic test for anti-MuSK antibodies or anti-AChR antibodies
  • meet additional criteria

The trial is taking place at more than a dozen study sites across the United States. Support for travel costs may be available.

To learn more about this trial, visit and enter NCT03304054 into the “Other Terms” search box, or visit the Catalyst Pharmaceuticals website.