Catalyst Pharmaceuticals Inc. is seeking approval in the U.S. for its Lambert-Eaton myasthenic syndrome treatment Firdapse.

Lambert-Eaton myasthenic syndrome is a rare autoimmune disorder, most often characterized by muscle weakness of the limbs.

The U.S. Food and Drug Administration previously rejected the drug in 2016.

The submission to FDA is supported by the positive results of a phase 3 trial the company conducted under the regulator's special protocol assessment process. Firdapse demonstrated statistically significant improvements in arm and leg strength as well as face and neck muscle performance.