The Company also reports that it remains on track to complete enrollment in its clinical trial of amifampridine phosphate in patients with anti-MuSK antibody positive myasthenia gravis(MuSK-MG) before the end of this year, and to reporttop-line data from this trial in the first half of 2020. We also expect to reporttop-line results from our SMAType-3 proof of concept study in the first half of 2020. Both of these diseases have a much more homogeneous patient population than CMS and should not present the same challenges.
“We have made significant progress in genetically testing patients who were unable to previously get diagnosed,” added Steven Miller, Ph.D., Chief Operating Officer and Chief Scientific Officer of Catalyst Pharmaceuticals. “Due to the small patient prevalence, the low number of patients tested, and heterogeneity of the disease with a wide range of variation in clinical presentation across its more than 50 subtypes, it was challenging to demonstrate a statistically significant benefit across multiple subtypes.”
About Congenital Myasthenic Syndromes (CMS)
Congenital myasthenic syndromes, or CMS, are rare neuromuscular disorders comprising a spectrum of more than 50 genetic defects with some of the various mutations having as few as a handful of diagnosed patients. CMS patients are characterized by fatigable weakness of skeletal muscles with onset at or shortly after birth or early childhood; in rare cases, symptoms may not manifest themselves until later in childhood. The severity and course of the genetic disease types are variable, ranging from minor symptoms to progressive disabling weakness; symptoms may be mild, but sudden severe exacerbations of weakness or even sudden episodes of respiratory insufficiency also occur.
CMS is rare. Catalyst estimates that there are between 1,000 and 1,500 CMS patients in the United States.
About MuSK Myasthenia Gravis (MuSK-MG)
About 15% of Myasthenia Gravis, or MG, patients test negative for the acetylcholine receptor antibody, and about40-50% of these “seronegative MG” patients are test positive for theMuSK-MG antibody and are identified asMuSK-MG patients, representing about 4,500 patients in the United States. MuSK is a protein that is required for the maintenance of the neuromuscular junction.MuSK-MG is a clinically distinguishable, more severe form of MG. The disease is characterized by a predominance in females, a prevalent involvement of cranial and bulbar muscles, high incidence of respiratory crises and a resistance to treatment. Although many patients withMuSK-MG are presently treated with anticholinesterase inhibitors or immunosuppressants, such patients do not generally respond adequately to these treatments.
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), anti-MuSK antibody positive myasthenia gravis(MuSK-MG), congenital myasthenic syndromes (CMS), 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 approved in November 2018 by the U.S. Food & Drug Administration (“FDA”), and Firdapse is now commercially available in the United States.
Firdapse is currently being evaluated in clinical trials for the treatment ofMuSK-MG, CMS, and SMA Type 3 and has received Orphan Drug Designation from the FDA for myasthenia gravis and CMS. Firdapse (amifampridine) 10 mg tablets is the first and only approved drug in Europe for the symptomatic treatment in adults with LEMS.
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