CMS-001 Phase III study of Firdapse fails to meet primary endpoint in Congenital Myasthenic Syndromes.- Catalyst Pharma

Catalyst Pharmaceuticals announced top-line results from CMS-001, a Phase III study evaluating amifampridine phosphate for the symptomatic treatment of genetically confirmed Congenital Myasthenic Syndromes (CMS) in adults and children aged 2 years and above. The Company�s lead product, Firdapse (amifampridine phosphate), is currently approved for the treatment of Lambert-Eaton Myasthenic Syndrome (LEMS) in adults, and amifampridine phosphate is being investigated for the treatment of CMS and other neuromuscular and neurological disease to support applications to FDA for these indications.

CMS-001 is the first ever double-blind, placebo-controlled, clinical trial conducted in genetically confirmed CMS patients. In the trial, 20 subjects were enrolled and 16 randomized, in a 2 period, 2 treatment crossover study designed to evaluate the efficacy and safety of amifampridine phosphate in patients (aged 2 years and above) diagnosed with certain genetic subtypes of CMS. While individual patient improvements were observed in some patient sub-groups, the trial did not meet its primary endpoint of subject global impression (SGI) or the secondary endpoint of muscle function measure (MFM) across all tested subtypes. Due to the rarity of CMS, this trial took almost 4 years to recruit.

Comment: Catalyst is scheduled to meet with the FDA before the end of the year to discuss the outcome of this clinical trial, and potential paths forward to seek approval of amifampridine phosphate for the symptomatic treatment of some subset of genetic subtypes of CMS. After receiving additional guidance, Catalyst will provide future updates on its plans for this potential indication.