Catalyst is Meeting with the FDA to Discuss the Future of Firdapse for Congenital Myasthenic Syndromes

Firdapse, or amifampridine phosphate, is a medication currently approved for Lambert-Eaton myasthenic syndrome, or LEMS. However, Catalyst Pharmaceuticals has been working to evaluate if it can aid other neurological and neuromuscular disease patient populations. They are currently enrolling anti-MuSK antibody positive myasthenia gravis (MuSK-MG) patients for a trial. The company expects to complete enrollment for this investigation by the end of 2019 and report their findings within the first half of next year.

Additionally, they are completing a trial for spinal muscular atrophy type 3. This is a proof of concept study and results of which should be reported by the first half of 2020.

Unfortunately, one of their recently completed trials was not as successful as they had hoped. This trial was called CMS-001.


CMS-001 was a Phase 3 clinical trial evaluating Firdapse for congenital myasthenic syndromes (CMS) patients. The placebo-controlled trial enrolled 20 patients, who in total took 4 years to recruit. All participants were 2 years old or older and were diagnosed with a subset of CMS. The aim of this trial was to investigate the safety and efficacy of Firdapse for different subsets of CMS as it is not a very homogeneous disease and the treatment could work differently for different populations. There are 50 total subtypes of congenital myasthenic syndromes.

While a few patients did experience some improvements, the trial ultimately failed to meet both its primary or secondary endpoints. The primary endpoint was subject of global impression and the second was muscle function measure.

This is a setback for CMS, yes. However, even a failure tells researchers more information. Each failure is still progress in its own right.

Looking Forward

Catalyst is meeting with the FDA soon to discus this trial and whether or not Firdapse should be investigated further for individual subsets of CMS. Following this meeting, the company will announce its next steps to the public.

Despite the unknown future of Firdapse for CMS, Catalyst is very hopeful for its efficacy in MuSK-MG and SMA as these are much more homogeneous diseases.

You can read more  about these investigations here.

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