PTC Therapeutics, Inc.
(PTC), today announced the initiation of 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.



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."



About Duchenne and Becker Muscular Dystrophy



Duchenne and Becker muscular dystrophy (DMD/BMD) are progressive muscle
disorders that cause the loss of both muscle function and independence.
DMD/BMD is perhaps the most prevalent of the muscular dystrophies and is
the most common lethal genetic disorder diagnosed during childhood.
Each year, approximately 20,000 children worldwide are born with DMD (one
of every 3,500 male children). 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. More information regarding DMD
and BMD is available through the Muscular Dystrophy Association
(http://www.mdausa.org), the Parent Project Muscular Dystrophy
(http://www.parentprojectmd.org), and the Association Francaise contre les
Myopathies (http://www.afm-france.org).



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
Duchenne muscular dystrophy (DMD) and cystic fibrosis (CF).



It is estimated that 13% of the cases of DMD and 10% of the cases of CF
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). For additional information on the
PTC124 clinical trial, please visit http://www.clinicaltrials.gov and search using
the keyword: PTC124.



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,
http://www.ptcbio.com.


PTC Therapeutics, Inc.

http://www.ptcbio.com