> ## Content Index
> Fetch the complete content index at: https://www.fdaweb.com/llms.txt
> Use this file to discover other available public pages before exploring further.

# FDA Refuses Catalyst NDA for Firdapse
- URL: https://www.fdaweb.com/fda-refuses-catalyst-nda-for-firdapse/
- Published: 2016-02-17T12:00:00.000Z
- Updated: 2026-09-15T02:36:36.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5134789

> FDA has issued Catalyst Pharmaceuticals a “Refusal to File” letter on its NDA for Firdapse (amifampridine phosphate), an investigational drug candidate for symptomatic treatment of Lambert Eaton myasthenic syndrome (LEMS) and congenital myasthenic syndromes (CMS). The letter says that after a preliminary review, the agency determined that the submission was not sufficiently complete. It requests additional supporting information, and Catalyst plans to request a meeting with the agency to understand the request in order to gain NDA acceptance and review.  
>  
> Both LEMS and CMS are rare, annually affecting about 3,000 and 1,000-1,500 U.S. patients, respectively. The NDA includes more than 60 pre-clinical and clinical studies conducted over the past five years by both Catalyst and BioMarin Pharmaceutical, according to the company. It also includes a request for a priority review. Previously, Firdapse received breakthrough therapy and orphan drug designations.