Catalyst Pharmaceuticals' Firdapse garners FDA approval for Lambert-Eaton myasthenic syndrome

The FDA announced the approval of Catalyst Pharmaceuticals' Firdapse (amifampridine) for the treatment of Lambert-Eaton myasthenic syndrome (LEMS) in adults, marking the first clearance of a drug for the autoimmune disorder. The company noted that the oral drug will be launched early in the first quarter of 2019.

"The approval of Firdapse is a crowning achievement for our company and an important step forward in our transition into a premier neurological rare disease company," remarked CEO Patrick McEnany. The executive added "we continue to prepare for what we hope will be a successful launch based on productive discussions with payers, our efforts in patient identification and our development of a field-based commercial infrastructure."

The approval was supported by data from the two late-stage studies in which 64 adults with LEMS received either Firdapse or placebo. Results, which were reported in 2014 and 2017, showed that on the measures of Quantitative Myasthenia Gravis score and the Subject Global Impression, patients receiving Firdapse experienced a greater benefit than those on placebo. 

Commenting on treatments for the condition, Oppenheimer analyst Leland Gershell noted that "there are drugs that are used off label to treat LEMS symptoms here in the US with varying degrees of efficacy and tolerability, but with respect to approved drugs, it is the first approval and there aren't any competing drugs in development for LEMS either." Analysts at SunTrust Robinson Humphrey estimate that Firdapse will generate sales of nearly $375 million for LEMS in 2025.

Catalyst Pharmaceuticals gained rights to Firdapse in North America from BioMarin Pharmaceutical under a deal signed in 2012. The therapy, which is a nonspecific, voltage-dependent, potassium channel blocker, was authorised in Europe in 2009 where it is marketed by BioMarin.

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