Catalyst Seeks FDA Approval of Firdapse for Treatment of LEMS

Catalyst Pharmaceuticals filed a New Drug Application (NDA) with the U.S. Food and Drug Administration for Firdapse (amifampridine) as a treatment for Lambert-Eaton myasthenic syndrome (LEMS).

“We are pleased to reach this regulatory milestone and believe that our NDA submission contains all of the necessary information to satisfy the FDA requirements,” Patrick J. McEnany, chairman and CEO of Catalyst, said in a press release.

“This important milestone is the culmination of a strong collaboration and commitment among the patients, physicians and Catalyst employees who have worked diligently to advance Firdapse and to further expand access to an FDA-approved product to all LEMS patients,” McEnany said.

“We look forward to continuing to work with the FDA during the review process and to a potential future launch of Firdapse, if it is approved,” he added.

In February, Catalyst announced that after a meeting with the FDA, its proposed filing package would be sufficient for submitting an NDA for Firdapse.

The company is seeking regulatory approval after reporting positive top-line results from its LMS-003 Phase 3 clinical trial (NCT02970162). The double-blind study was conducted under a protocol agreed to by the FDA specifically evaluated the effects of withdrawing Firdapse treatment from LEMS patients.

Catalyst recruited 26 adult patients who were randomly assigned to a four-day oral treatment with either 10 mg Firdapse, 30 to 80 mg total daily dose, or a placebo. Among other benefits, treatment with Firdapse led to clinically relevant differences compared to placebo in quantitative myasthenia gravis score — a 13-item physician-rated assessment of arm and leg strength, face and neck muscle performance, swallowing, speech, grip strength, forced respiration, and gaze.

Firdapse received breakthrough therapy designation from the FDA for the treatment of LEMS, as well as orphan drug status for LEMS, congenital myasthenic syndromes (CMS) and myasthenia gravis. Firdapse is the only approved medication in Europe for the symptomatic treatment of adults with LEMS.

In 2016, Catalyst had a previous NDA application refused by the FDA. The agency ruled the application was not sufficiently complete and requested additional information. Upon submission of an NDA, the FDA has 60 days to decide whether it is complete and acceptable for filing.

In its FDA submission, the company decided not to include limited types of CMS similar to LEMS. This decision was intended to not overcomplicate the FDA’s review of Firdapse for LEMS.

Catalyst is currently recruiting participants for a Phase 3 clinical study (NCT02562066) of Firdapse to treat CMS, which the company expects to complete before the end of the year. Announcement of top-line results are planned for the first quarter of 2019.

LEMS is a rare autoimmune disease characterized by progressive muscle weakness, especially in the pelvic and thigh muscles. About 60 percent of LEMS cases are associated with a small-cell lung cancer. LEMS symptom onset often precedes a cancer diagnosis.