Enrollment Completed in Phase 3 of Firdapse in Lambert-Eaton Myasthenic Syndrome

Mathew Shanley

The LMS-003 Phase 3 trial evaluating Firdapse (amifampridine phosphate) in patients with Lambert-Eaton Myasthenic Syndrome (LEMS) has completed enrollment, Catalyst Pharmaceuticals, Inc. announced today.

LMS-003 is a double-blind, placebo controlled withdrawal trial that enrolled 26 subjects with the co-primary endpoints of change from Baseline Quantitative Myasthenia Gravis (QMG) score, and change in Subject Global Impression (SGI) score. The endpoints are consistent with the endpoints of Catalyst’s first Phase 3 that evaluated Firdapse for the treatment of LEMS.

Myasthenia gravis is a chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of the body’s skeletal muscles. The disease is characterized by the progressive worsening of muscle weakness during periods of activity. Patients with the condition develop antibodies that interfere with acetylcholine receptors at the neuromuscular junction.

The drug has previously been granted orphan drug designation for congenital myasthenia gravis and LEMS, but earlier in the year, Catalyst received a “Refusal to File” letter from the U.S. Food and Drug Administration (FDA), stating that not enough information was found after preliminary review of the initial application.

“Completion of enrollment in LMS-003 marks a significant milestone for Catalyst as well as the LEMS community as we take another step toward advancing treatment for LEMS patients,” commented Patrick J. McEnany, Chief Executive Officer of Catalyst in a press release. “We would like to express our thanks to the dedicated investigators and clinical site coordinators who are conducting the trial and also patients with LEMS and their caregivers who are participating. We look forward to reporting top-line results in early December.”

While many patients with myasthenia gravis develop the aforementioned antibodies, some do develop antibodies to MuSK-a surface membrane enzymes that assist in the regulation of acetylcholine receptors. These patients are generally treated with anticholinesterase inhibitors or immunosuppressants, however, do not always respond adequately. Because of this, Catalyst is also developing Firdapse for the treatment of MuSK antibody positive myasthenia gravis (MuSK-MG) and congenital myasthenic syndromes (CMS).

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