Catalyst Pharmaceuticals has submitted a New Drug Application (NDA) for Firdapse (amifampridine) for the symptomatic treatment of Lambert-Eaton myasthenic syndrome (LEMS). 

The NDA is supported by results from a Phase 3 trial (LMS-002) which evaluated Firdapse in patients ≥18 years with a confirmed diagnosis of LEMS. Patients were randomized for 2 weeks of treatment to amifampridine phosphate given 3-4 times per day (30–80mg/day) with a maximum single dose of 20mg (n=21) or matching placebo (n=16). Results showed that the Quantitative Myasthenia Gravis (QMG) score from baseline to day 14 changed from 6.4 to 6.7 in the amifampridine group vs. 5.6 to 7.9 for the placebo group.  

Related Articles

The QMG includes 13 physical assessments; increased QMG total score correlates to worsening symptoms of LEMS. The Food and Drug Administration (FDA) indicated in the minutes of a Type C meeting with the Company that the proposed filing package would be sufficient for an NDA submission. 

LEMS is a rare autoimmune disorder, most often characterized by muscle weakness of the limbs. In ~50% of cases, LEMS is associated with an underlying malignancy, most commonly small-cell lung cancer.  

“We look forward to continuing to work with the FDA during the review process and to a potential future launch of Firdapse, if it is approved,” said Patrick J. McEnany, CEO of Catalyst Pharmaceuticals. The Company is also currently conducting a Phase 3 trial to examine Firdapse in patients with congenital myasthenic syndromes (CMS), which are considered mechanistically similar to LEMS. 

For more information visit