PTC Therapeutics starts phase 2 study of PTC124 for muscular dystrophy

By Lisa Kerner

Erie, Pa., Jan. 27 - PTC Therapeutics, Inc. said it has begun a phase 2 study of PTC124 in patients with Duchenne muscular dystrophy due to a nonsense mutation.

PTC124 is a novel, orally administered drug that targets nonsense mutations. It is being investigated initially as a treatment for Duchenne muscular dystrophy and cystic fibrosis, according to a company news release. Other potential indications for PTC124 include hemophilia, neurofibromatosis, retinitis pigmentosa, epidermolysis bullosa, and lysosomal storage disorders.

The multi-site, open-label, dose-ranging phase 2 clinical study is enrolling patients who have a nonsense mutation in the dystrophin gene. The primary endpoint of the clinical study is assessment of muscle dystrophin expression in response to treatment with PTC124. Other assessments include the presence of dystrophin mRNA and dystrophin-related proteins, muscle function, compliance with treatment, safety and pharmacokinetics, the company said.

Recruitment for the study is underway at the Children's Hospital of Philadelphia, the Cincinnati Children's Hospital Medical Center and University of Utah in Salt Lake City.

"With the initiation of the phase 2 study, we hope to establish proof-of- concept for PTC124 in nonsense-mutation-mediated [Duchenne muscular dystrophy]," Dr. Langdon Miller, PTC chief medical officer, said in the release. "Demonstration of pharmacological activity in this study would be an important step toward evaluating the longer-term clinical benefits of PTC124."

PTC said it also has phase 2 clinical trials for PTC124 underway with cystic fibrosis patients in the United States and in Israel.

Nonsense mutations are alterations in the genetic code that prematurely halt the translation process, producing a shortened, non-functional protein. In pre-clinical trials, PTC124 allowed the cellular machinery to bypass the nonsense mutation, the company said.

An estimated 10% of cystic fibrosis cases and 15% of Duchenne muscular dystrophy cases are due to nonsense mutations.

The Food and Drug Administration has granted PTC124 fast-track designation for the treatment of cystic fibrosis and orphan drug designations for the treatment of cystic fibrosis and Duchenne muscular dystrophy due to nonsense mutations. PTC124 has also been granted orphan drug status for the treatment of Duchenne muscular dystrophy and cystic fibrosis by the Committee for Orphan Medicinal Products of the European Medicines Agency.

PTC is a privately held biopharmaceutical company focused on the discovery, development and commercialization of small-molecule drugs. The company is based in South Plainfield, N.J.

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