Catalyst Pharmaceuticals announced the enrollment of the first patient in its new Phase 3 clinical trial of amifampridine phosphate (Firdapse) in patients with muscle-specific kinase (MuSK) antibody positive myasthenia gravis (MuSK-MG).
Myasthenia gravis (MG) is a rare autoimmune disease that affects the neuromuscular junction, which is the site where nerve cells and muscle cells communicate, while MuSK is a second chemical necessary for proper nerve-muscle communication. MuSK-MG is when the patients’ bodies attack cells that produce the MuSK chemical needed to conduct nerve-muscle communication across the neuromuscular junction. Approximately 8% of all people with MG in the US suffer from the MuSK-MG type (about 3,000-4,800 total patients).
“By conducting this Phase 3 study in patients with MuSK-MG, we hope to provide a potential treatment option for people suffering from this rare condition,” said Patrick J. McEnany, Chairman and CEO of Catalyst. “Catalyst continues to build a leadership position in developing therapies to treat rare neuromuscular diseases with this next step for an important investigational product to potentially treat the symptoms of MuSK-MG.”
In August 2017, Catalyst announced that it had reached an agreement with the U.S. Food and Drug Administration (FDA) under a Special Protocol Assessment (SPA) for the protocol design, clinical endpoints, and statistical analysis approach in the Phase 3 trial. Catalyst has also received Orphan Drug designation for Firdapse for the treatment of Myasthenia Gravis.
About the MSK-002 Clinical Trial
Catalyst previously announced that it had reached agreement with the FDA on a special protocol assessment for its Phase 3 trial (designated as MSK-002) of Firdapse in patients with MuSK-MG. This is a particularly severe form of myasthenia gravis that affects about 3,000 to 4,800 patients in the U.S., for which there are no approved effective therapies and is therefore an unmet medical need. The double-blind, placebo-controlled withdrawal trial will be conducted at clinical trial sites in the U.S. and Italy and is targeted to enroll about 60 subjects diagnosed with MuSK-MG. The trial will employ a primary endpoint of Myasthenia Gravis Activities of Daily Living (MG-ADL) and a secondary endpoint of Quantitative Myasthenia Gravis Score (QMG). At the FDA’s request, the trial will also enroll up to 10 generalized myasthenia gravis patients who will be assessed with the same clinical endpoints, but achieving statistical significance in this subgroup of patients is not required and only summary statistics will be provided. We anticipate that it will take about 12 months to complete the enrollment for the trial.
Additional information about MSK-002 can be found on www.clinicaltrials.gov (NCT03304054).
