Catalyst Pharmaceuticals Announces Publication of Phase 3 Clinical Trial Data for Firdapse® for the

Catalyst Pharmaceuticals Announces Publication of Phase 3 Clinical Trial Data for Firdapse® for the Treatment of Lambert-Eaton Myasthenic Syndrome

CORAL GABLES, Fla., Feb. 26, 2019 (GLOBE NEWSWIRE) -- Catalyst Pharmaceuticals, Inc. (Catalyst) (Nasdaq: CPRX), a biopharmaceutical company focused on developing and commercializing innovative therapies for people with rare debilitating, chronic neuromuscular and neurological diseases, today announced the online publication in the Journal of Clinical Neuromuscular Disease of the results of its second Phase 3 clinical trial (LMS-003) evaluating Firdapse® (amifampridine phosphate) for the treatment of Lambert-Eaton Myasthenic Syndrome (LEMS).

The positive topline results from this trial were previously announced, but the full results of safety, efficacy, and other clinical data are now available online. The LMS-003 trial was a randomized, double-blind, placebo-controlled design. Both co-primary endpoints were met with statistical significance (QMG score: p=0.0004 and Subject Global Impression Score: p=0.0003). This was further supported by similar success with other endpoints (Triple Timed Up and Go walk test and the Clinical Global Impression of Improvement). The study provided statistically and clinically significant evidence that Firdapse was safe and effective in treating LEMS patients.

These data are more fully described in the manuscript entitled, “Amifampridine Phosphate (Firdapse) Is Effective in a Confirmatory Phase 3 Clinical Trial in LEMS”. The article can be accessed at the Journal of Clinical Neuromuscular Disease 2019;20:111-119.

https://journals.lww.com/jcnmd/Fulltext/2019/03000/Amifampridine_Phosphate__Firdapse__Is_Effective_in.2.aspx

“The results of this second pivotal Phase 3 trial again demonstrate that Firdapse is effective for the treatment of LEMS,” said Gary Ingenito, M.D., Ph.D., Chief Medical Officer of Catalyst Pharmaceuticals. “We are pleased to offer access, for all adults LEMS patients, to the first FDA approved, evidence-based treatment available in the United States.”

About Catalyst Pharmaceuticals

Catalyst Pharmaceuticals is a biopharmaceutical company focused on developing and commercializing innovative therapies for people with rare debilitating, chronic neuromuscular and neurological diseases, including Lambert-Eaton myasthenic syndrome (LEMS), congenital myasthenic syndromes (CMS), MuSK antibody positive myasthenia gravis (MuSK-MG), and spinal muscular atrophy (SMA) Type 3. Catalyst's new drug application for Firdapse® (amifampridine) 10 mg tablets for the treatment of adults with LEMS was recently approved by the U.S. Food & Drug Administration ("FDA"), and Firdapse is now commercially available in the United States. Prior to its approval, Firdapse for LEMS had received breakthrough therapy designation and orphan drug designation from the FDA.

Firdapse is currently being evaluated in clinical trials for the treatment of CMS, MuSK-MG and SMA Type 3 and has received Orphan Drug Designation from the FDA for CMS and myasthenia gravis. Firdapse (amifampridine) 10 mg tablets is the first and only approved drug in Europe for the symptomatic treatment in adults with LEMS.

Forward-Looking Statements

This press release contains forward-looking statements. Forward-looking statements involve known and unknown risks and uncertainties, which may cause Catalyst's actual results in future periods to differ materially from forecasted results. A number of factors, including (i) whether Catalyst will be successful in commercializing Firdapse, (ii) whether, even if Catalyst is successful in commercializing Firdapse, Catalyst will become profitable, (iii) whether Firdapse will ever be approved for the treatment of CMS, MuSK-MG, SMA Type 3, or any other disease, and (iv) those other factors described in Catalyst's Annual Report on Form 10-K for the fiscal year 2017 and its other filings with the U.S. Securities and Exchange Commission (SEC), could adversely affect Catalyst. Copies of Catalyst's filings with the SEC are available from the SEC, may be found on Catalyst's website, or may be obtained upon request from Catalyst. Catalyst does not undertake any obligation to update the information contained herein, which speaks only as of this date.

Investor Contact Brian Korb Solebury Trout (646) 378-2923 Company Contact Patrick J. McEnany Catalyst Pharmaceuticals Chief Executive Officer (305) 420-3200 Media Contact David Schull Russo Partners (212) 845-4271