PTC Therapeutics Announces Publication of Preclinical Data in PNAS
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PTC Therapeutics, Inc. today announced the publication of new preclinical data in the February 12, 2008 edition of the Proceedings of the National Academy of Sciences (PNAS) which show that PTC124, a novel drug designed to bypass nonsense mutations, was active in a preclinical model of cystic fibrosis (CF). These results support and add to research published last year in the journal Nature, which demonstrated the activity of PTC124 in a preclinical model of Duchenne muscular dystrophy (DMD). PTC124 has demonstrated pharmacodynamic proof of concept in Phase 2a clinical trials in nonsense-mutation-mediated CF and DMD.

PTC has catalogued over 2,400 distinct genetic disorders where nonsense mutations are the cause of the disease in a significant percentage of patients.  Nonsense mutations inactivate gene function and are known to cause anywhere from five to 70 percent of the individual cases of most inherited diseases, such as cystic fibrosis (10%) and Hurler's syndrome (70%).

“The preclinical and clinical data on PTC124 support our hope that this drug will be an important disease-modifying therapy for cystic fibrosis,” said Robert J. Beall, Ph.D., President and CEO of the Cystic Fibrosis Foundation. “This is an exciting potential new treatment for patients afflicted with nonsense-mutation-mediated CF. We look forward to the next stage of clinical development to demonstrate the benefits of this promising new investigational drug.”

As with the DMD data published in Nature, the results published in PNAS further demonstrate that PTC124 targets genetic mutations in a completely new way. PTC124 functions by overcoming the premature stop signal and reading through the complete genetic instructions, resulting in the restoration of a full-length, functional protein. Patients with CF lack the CFTR protein, a chloride channel that maintains proper hydration of epithelial cells in the lung, pancreas, and liver. The data in PNAS demonstrate that PTC124 allows CFTR to be made in cells in which it was previously absent, to be delivered to the proper cellular location, and to induce chloride channel function. Collectively, these results indicate that this new approach may ultimately be applicable to a subset of patients across a large number of genetic disorders.

The paper entitled, “PTC124 is an orally bioavailable compound that promotes suppression of the human CFTR-G542X nonsense allele in a CF mouse model,” will be available in an advanced online publication of PNAS during the week of February 4, 2008 (http://www.pnas.org/papbyrecent.shtml).  This publication is the result of collaborative efforts between the University of Alabama at Birmingham and PTC Therapeutics.

“These preclinical data further demonstrate the potential applicability of the PTC124 mechanism of action to multiple genetic disorders,” said Stuart W. Peltz, Ph.D., President and Chief Executive Officer of PTC Therapeutics.  “We look forward to further evaluating PTC124 in registration-directed clinical trials in both CF and DMD this year, as well as in studies in additional genetic disorders in the future.”

About PTC124

PTC124 is an orally delivered investigational new drug in Phase 2 clinical development for the treatment of genetic disorders due to nonsense mutations.  Nonsense mutations are single-point alterations in the genetic code that prematurely halt the translation process, producing a shortened, non-functional protein.  PTC124 has restored production of full-length, functional proteins in preclinical genetic disease models harboring nonsense mutations.  In Phase 1 clinical trials, PTC124 was generally well tolerated, achieved target plasma concentrations that have been associated with activity in preclinical models and did not induce ribosomal read through of normal stop codons.  PTC124 has demonstrated pharmacodynamic proof of concept in Phase 2a clinical trials in nonsense-mutation-mediated cystic fibrosis (CF) and Duchenne muscular dystrophy (DMD).

It is estimated that 10% of the cases of CF and 13% of the cases of DMD are due to nonsense mutations.  PTC believes that PTC124 is potentially applicable to a broad range of other genetic disorders in which a nonsense mutation is the cause of the disease.  The FDA has granted PTC124 Subpart E designation for expedited development, evaluation and marketing and has granted Orphan Drug designations for the treatment of CF and DMD due to nonsense mutations.  PTC124 has also been granted orphan drug status for the treatment of CF and DMD by the European Commission.  PTC124's development has been supported by grants from the Muscular Dystrophy Association (MDA), Cystic Fibrosis Foundation Therapeutics, Inc. (CFFT), Parent Project Muscular Dystrophy (PPMD), FDA's Office of Orphan Products Development (OOPD) and by General Clinical Research Center grants from the National Center for Research Resources (NCRR).

About the Cystic Fibrosis Foundation

The Cystic Fibrosis Foundation is the leading organization devoted to curing and controlling cystic fibrosis. Headquartered in Bethesda, Md., the Foundation funds CF research, has 80 chapter and branch offices, and supports and accredits a nationwide network of 115 CF care centers, which provide vital treatments and other CF resources to patients and families. For more information, visit www.cff.org.

About PTC Therapeutics, Inc.

PTC is a biopharmaceutical company focused on the discovery, development and commercialization of orally administered, proprietary, small-molecule drugs that target post-transcriptional control processes.  Post-transcriptional control processes regulate the rate and timing of protein production and are of central importance to proper cellular function.  PTC's internally-discovered pipeline addresses multiple therapeutic areas, including genetic disorders, oncology and infectious diseases.  In addition, PTC has developed proprietary technologies and extensive knowledge of post-transcriptional control processes that it applies in its drug discovery and development activities, including the Gene Expression Modulation by Small-molecules (GEMS) technology platform, which has been the basis for collaborations with leading pharmaceutical and biotechnology companies such as Pfizer, Celgene, CV Therapeutics and Schering-Plough.  For more information, visit the company's website, www.ptcbio.com

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