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PTC Therapeutics Initiates Trial Of PTC124 In Muscular Dystrophy

Armen Hareyan's picture

PTC Therapeutics initiates an international pivotal trial of PTC124 in patients with Duchenne/Becker muscular dystrophy (DMD/BMD) due to a nonsense mutation. The primary objective of this registration-directed Phase 2b trial is to demonstrate the efficacy of PTC124 as measured by improvements in the walking ability of patients with this progressive genetic disease.

"DMD/BMD is a disorder with a significant need for better treatment options, and we are very encouraged by the promising results we have seen to date with PTC124," said Brenda Wong, M.D., Associate Professor of Pediatrics and Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, who was involved in the Phase 2a study and is one of the trial's lead investigators. "We believe that the safety profile of PTC124 and activity we have seen in the Phase 2a studies clearly support the initiation of this longer-term, registration-directed efficacy and safety study. We are very pleased to be a part of this groundbreaking trial."

Patients with DMD and BMD are boys and young men who lack dystrophin, a protein that is critical to the structural stability of muscle fibers. Patients develop progressive muscle weakness that leads to loss of ambulation, wheelchair dependency, and eventual decline in respiratory and cardiac function. It is estimated that one in 10 DMD patients are likely to have a Becker presentation, a milder form of the disease that is associated with later manifestation of symptoms. In essence, DMD and BMD represent a continuum of the same disease.

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PTC124 is a novel, orally delivered drug in development for the treatment of patients with genetic disorders due to a nonsense mutation, a type of mutation found in approximately 13% of patients with DMD. In this double-blind study, patients will be randomized to receive placebo, or one of two dose levels of PTC124, three times per day. Eligible patients will be boys with nonsense-mutation-mediated DMD/BMD who are at least 5 years of age and are able to walk at least 75 meters or approximately 80 yards in six minutes. PTC expects to enroll a total of 165 patients at approximately 35 investigational sites; all study subjects will undergo 48 weeks of blinded treatment. Thereafter, all participants, including those who have been receiving placebo, will be eligible to enroll in an open-label PTC124 extension study.

The primary outcome measure is the total distance walked during a 6-minute walk test, a test of ambulation that has now been standardized for boys with DMD/BMD through a collaboration with noted investigator, Craig McDonald, M.D., at University of California at Davis. Other outcome measures in the Phase 2b study will evaluate activity at home, muscle and heart function, strength, cognitive ability, muscle integrity, and muscle dystrophin expression. Safety parameters, compliance, and PTC124 blood levels also will be monitored.

"We are very pleased to announce the initiation of the Phase 2b trial for PTC124 in boys with DMD/BMD," said Langdon Miller, M.D., Chief Medical Officer of PTC. "We applaud the patients, parents, and clinicians who have committed themselves to this effort. The design of this trial reflects our ongoing collaboration with the advocacy community, investigators at leading neuromuscular centers, and the U.S. and European regulatory agencies. We hope that PTC124 will soon offer a treatment that addresses the underlying cause of the disease for patients with nonsense-mediated DMD/BMD and that the development of PTC124 will set the stage for improving therapeutic options in this disabling and life-threatening disorder."

Stuart W. Peltz, Ph.D., President and Chief Executive Officer of PTC Therapeutics added, "Initiation of the Phase 2b trial is an important milestone for PTC. The trial builds on the results we have achieved to date in DMD and cystic fibrosis (CF) and constitutes a major step forward in establishing the potential for PTC124 as a paradigm shift in the treatment of genetic disorders. Our future plans for PTC124 include the initiation of longer-term studies in CF, as well as additional proof-of-concept studies in other indications."