Catalyst Pharmaceutical Partners Gets Breakthrough Therapy Designation, Stock Soars 41.55%

Catalyst Pharmaceutical Partners, Inc. recently announced its investigational product Firdapse (amifampridine phosphate) has received Breakthrough Therapy Designation by the US FDA for the symptomatic treatment of patients with Lambert-Eaton Myasthenic Syndrome (LEMS). Firdapse is Catalyst’s investigational therapy being evaluated for the treatment of the debilitating symptoms associated with LEMS, including muscle weakness.

“We are very pleased to have received Breakthrough Therapy Designation for Firdapse, and we are excited by the FDA’s decision to place our product in a category that may enable expedited development and review for patients with LEMS,” said Patrick McEnany, President and CEO of Catalyst. “With no approved or effective symptomatic treatment currently available for LEMS, Firdapse has the potential to be the first-line treatment option for patients with this rare condition.”

Breakthrough Therapy Designation for Firdapse was based on clinical data from several previously published clinical trials of amifampridine (3,4-DAP) in patients with LEMS. Firdapse has the potential to provide significant relief of the often debilitating symptoms of the disease, including muscle weakness (eg, difficulty walking), difficulty swallowing and talking, drooping of eyelids, and facial weakness.

Breakthrough Therapy Designation was enacted as part of the 2012 Food and Drug Administration Safety and Innovation Act (FDASIA). FDASIA defines breakthrough therapy as a drug that is “intended, alone or in combination with one or more other drugs, to treat a serious or life-threatening disease or condition and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development.”

A breakthrough therapy designation conveys all of the fast track program features, as well as more intensive FDA guidance on an efficient drug development program. The FDA also has an organizational commitment to involve senior management in such guidance. The Breakthrough Therapy Designation is a distinct status from both accelerated approval and priority review, which can also be granted to the same drug if relevant criteria are met.

Firdapse, also known as amifampridine phosphate, 3,4-diaminopyridine phosphate or 3,4-DAP phosphate, is a potassium channel blocker. It delays repolarization of the pre-synaptic neuron, causing voltage gated Ca2+ channels to remain open longer. The increase Ca2+ influx causes more acetylcholine to be released, making it more likely that a muscle action potential will be initiated, thereby reducing muscle weakness. The North American rights to Firdapse were licensed to the Company in 2012 by BioMarin Pharmaceutical. BioMarin currently markets Firdapse in the EU for the treatment of LEMS.

In the US, where the product has previously received orphan drug designation, Firdapse is in a Phase III, multicenter, double-blind, placebo-controlled, randomized discontinuation study followed by an open-label extension period to evaluate the efficacy and safety of Firdapse in patients with LEMS. In addition to LEMS, other potential orphan neuromuscular indications for Firdapse include Myasthenia Gravis and Congenital Myasthenic Syndrome, among others.

Lambert-Eaton Myasthenic Syndrome, LEMS, is a rare autoimmune disease that can be severely disabling, with the primary symptom of muscle weakness. The weakness is generally more marked in the proximal muscles, particularly of the legs and trunk. Other problems include reduced reflexes, drooping of the eyelids, facial weakness and problems with swallowing. Patients often report dry mouth, impotence, constipation and feelings of light headedness on standing. These problems can be life threatening when the weakness involves respiratory muscles. The muscle weakness in LEMS is caused by autoantibodies to voltage gated calcium channels, which cause a reduction in the amount of acetylcholine released from nerve terminals. The prevalence of LEMS is estimated at approximately 3,000 patients in the United States and Canada. Approximately 50 percent of LEMS patients diagnosed have small cell lung cancer. Patients with LEMS typically present with fatigue, muscle pain and stiffness. A diagnosis of LEMS is generally made on the basis of clinical symptoms, electromyographic and compound muscle action potential (CMAP) testing and where available, the presence of autoantibodies against voltage gated calcium channel.

Catalyst Pharmaceutical Partners, Inc. is a specialty pharmaceutical company focused on the development and commercialization of novel prescription drugs targeting rare (orphan) neuromuscular and neurological diseases. For more information, visit www.catalystpharma.com.