05/04/2007 - PTC Therapeutics Announces Additional Positive Interim Phase 2 Results of PTC124 in Duchenne Muscular Dystrophy

05/02/2007 -PTC Therapeutics Announces Promotion of Neil Almstead to Senior Vice President of Chemistry and CMC

04/23/2007 - Targeting Specific Mutations Reveals Promising New Approach to Treating Genetic Disorders; Preclinical Data Published in Nature

04/20/2007 - PTC Therapeutics Withdraws IPO Registration Statement

01/8/2007 - PTC Therapeutics - PTC Therapeutics Announces Strategic Drug Discovery Collaboration with Pfizer Utilizing PTC’s GEMS Technology Platform

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PTC THERAPEUTICS PRESENTS ENCOURAGING PHASE 1 RESULTS OF ITS NOVEL VEGF INHIBITOR, PTC299, AT 30TH ANNUAL SAN ANTONIO BREAST CANCER SYMPOSIUM

- Company Initiates Phase1b/2 Clinical Trial in Breast Cancer -

SOUTH PLAINFIELD, NJ – December 17, 2007 - PTC Therapeutics, Inc. (PTC), a biopharmaceutical company focused on the discovery, development, and commercialization of small-molecule drugs targeting post-transcriptional control mechanisms announced the presentation of preclinical and Phase 1 data regarding PTC299, its novel, internally discovered, vascular endothelial growth factor (VEGF) inhibitor. PTC299 is an orally bioavailable investigational drug which is designed to inhibit the production of VEGF in tumors, acting upstream of current anti-angiogenic agents that function at the site of the VEGF receptor. The preclinical and clinical data presented today formed the basis for the recent initiation of a Phase 1b/2 clinical trial of PTC299 in patients with advanced breast cancer.

“We are pleased to present these preclinical data on PTC299, which show drug activity in multiple preclinical models of human cancer, including breast cancer,” said Langdon Miller, M.D., Chief Medical Officer of PTC Therapeutics, Inc. “Based on the safety profile and pharmacokinetic results from our Phase 1a studies, we are excited to have initiated a Phase 1b/2 trial of PTC299 in patients with advanced breast cancer. Our hope is that PTC299 will offer an active, well-tolerated, and convenient oral therapy for patients with breast cancer and other tumor types.”

The data were detailed in a poster presentation at the San Antonio Breast Cancer Symposium entitled, “Preclinical Efficacy in Breast Cancer Xenografts and Phase 1 Results of PTC299, a Novel VEGF Expression Inhibitor,” (Poster Number 6082).

In the preclinical studies, PTC299 was administered to mice harboring established human breast tumor xenografts. In these studies, PTC299 monotherapy significantly decreased human tumor and plasma VEGF levels, impeded tumor growth, and prolonged time to tumor progression in hormone-sensitive and -insensitive xenograft models. As assessed by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), PTC299 also significantly reduced xenograft tumor volume and tumor perfusion, with effects beginning within one day of treatment initiation.

In the Phase 1 clinical studies, healthy volunteers received single doses or multiple doses through seven days of drug administration. PTC299 induced no serious, dose-limiting, or definitively drug-related adverse events. All clinical adverse events were mild (Grade 1) or moderate (Grade 2) in severity and did not require intervention. Consistent with preclinical findings which suggest that PTC299 selectively inhibits pathological tumor-associated VEGF production while sparing physiological VEGF expression, adverse events such as bleeding, hypertension, or proteinuria that have been associated with other VEGF inhibitors were not observed. Pharmacokinetic data indicated dose-proportional increases in plasma exposures with trough plasma concentrations exceeding those associated with activity in the preclinical models of breast cancer.

Together, these preclinical and Phase 1a clinical data have supported the recent initiation of a randomized, dose-ranging Phase 1b/2 clinical trial in patients with advanced breast cancer at New York University Medical Center. In addition to assessing longer-term safety and anti-tumor activity, the trial will evaluate tumor perfusion and metabolism and assess circulating VEGF and tumor markers. For additional information on the PTC299 clinical trial, please visit www.clinicialtrials.gov and search using the keyword, PTC299.

Founded in 2003, the Spinal Muscular Atrophy Foundation is a nonprofit organization dedicated to accelerating progress towards a treatment and cure for spinal muscular atrophy through targeted funding of clinical research and novel drug development efforts. Since its inception, the Foundation has awarded over $40 million in sponsored research agreements. In addition, the Foundation is committed to raising awareness and generating support for increased research efforts in SMA among the leaders of industry and government. For more information on the Spinal Muscular Atrophy Foundation, visit www.smafoundation.org or call (646) 253-7100.

“The initiation of trials with PTC299 in patients with breast cancer provides further clinical validation of our proprietary GEMS technology. This is an important milestone for the company,” commented Stuart W. Peltz, Ph.D., President and CEO of PTC Therapeutics, Inc. “PTC299 is an example of the utilization of the GEMS technology to identify innovative oral small molecules with the opportunity to change the paradigm of treatment in areas of continued unmet medical need such as oncology and infectious diseases.”

About PTC299
PTC299 is a novel, orally administered small-molecule compound that inhibits the production of the protein vascular endothelial growth factor, or VEGF, in tumors. PTC discovered PTC299 through PTC’s proprietary GEMS (Gene Expression Modulation by Small-Molecules) technology by targeting the post-transcriptional processes that regulate VEGF formation. Overexpression of VEGF plays a key role in the growth of many types of cancers. PTC299 inhibits VEGF production through a mechanism that is distinct from other VEGF inhibitors and has potential application in the treatment of multiple solid tumor types.

About GEMS
Gene Expression Modulation by Small-molecules (GEMS) is PTC's novel and proprietary screening technology for the identification of small-molecules that modulate post-transcriptional control mechanisms. Compounds identified through the GEMS technology target processes that act through the untranslated regions (UTRs) of messenger RNA (mRNA) molecules. GEMS was the basis for the discovery of PTC299 and is being used in multiple ongoing drug discovery programs.

About Department of Defense Clinical Translational Research Award
In September 2006, the company received a $2.2 million award from the Department of the Army to fund development of PTC299 as a potential treatment for breast cancer. The Department of Defense Clinical Translational Research Award sponsors innovative preclinical and clinical/translational research that may result in substantial improvements over current approaches to breast cancer chemoprevention and therapy. As part of the Congressionally Directed Medical Research Programs, it administers funds for peer-reviewed research toward specific diseases and supports research that positively affects the health and well-being of Americans. For this grant (grant number W81XWH-06-1-0629), the U.S. Army Medical Research Acquisition Activity, 820 Chandler Street, Fort Detrick, MD 21702-5014 is the awarding and administering acquisitions office. The content of this press release does not necessarily reflect the position or the policy of the Government, and no official endorsement should be inferred.

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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- Expanded Collaboration Focuses on Discovery of
Small-Molecule Drugs for Spinal Muscular Atrophy -

SOUTH PLAINFIELD, NJ – December 6, 2007 - PTC Therapeutics, Inc. (PTC), a biopharmaceutical company focused on the discovery, development, and commercialization of small-molecule drugs targeting post-transcriptional control mechanisms, today announced an expanded research collaboration with the Spinal Muscular Atrophy (SMA) Foundation. The collaboration builds on the existing research agreement to identify and characterize compounds that have the potential to treat SMA by increasing production of the survival motor neuron (SMN) protein, the absence of which causes SMA. Under the terms of the expanded agreement, the SMA Foundation will provide an additional $1.6 million in funding to PTC based upon completion of certain milestones.

“We are pleased to expand this collaboration with the SMA Foundation,” stated Stuart W. Peltz, Ph.D., President and Chief Executive Officer of PTC Therapeutics. “By applying our proprietary technologies, we have made important progress in our efforts to identify treatments for SMA. This program is another example of the breadth of our approach and we look forward to our continued collaboration with the SMA Foundation as we seek to develop treatments for disorders with high unmet medical need.”

“PTC has been an ideal partner in the identification of molecules targeting SMN,” noted Meg Winberg, Director of Discovery Research for the SMA Foundation. “We have been impressed with their progress and are pleased to continue our work together to identify and advance potential treatments for SMA.”

About Spinal Muscular Atrophy
Spinal muscular atrophy (SMA) is a genetic, motor neuron disease characterized by the wasting of skeletal muscles. Caused by progressive degeneration of nerve cells in the spinal cord, the disease leads to increasing muscular weakness and atrophy. It is estimated that approximately 1 in 6,000 to 1 in 10,000 infants are born annually worldwide with SMA. SMA is often compared to polio because the same spinal cord cells are attacked in each disease. Over time, patients afflicted by this disease continue to lose muscle control and strength, leading to progressive inability to walk, stand, sit up and breathe.

About the Spinal Muscular Atrophy Foundation
Founded in 2003, the Spinal Muscular Atrophy Foundation is a nonprofit organization dedicated to accelerating progress towards a treatment and cure for spinal muscular atrophy through targeted funding of clinical research and novel drug development efforts. Since its inception, the Foundation has awarded over $40 million in sponsored research agreements. In addition, the Foundation is committed to raising awareness and generating support for increased research efforts in SMA among the leaders of industry and government. For more information on the Spinal Muscular Atrophy Foundation, visit www.smafoundation.org or call (646) 253-7100.

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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- Data Presented at the World Muscle Society International Congress -

SOUTH PLAINFIELD, NJ – October 18, 2007 - PTC Therapeutics, Inc. (PTC), a biopharmaceutical company focused on the discovery, development, and commercialization of small-molecule drugs targeting post-transcriptional control mechanisms, today announced additional data from a Phase 2 clinical trial of PTC124 in patients with Duchenne muscular dystrophy (DMD) due to a nonsense mutation. The results, which include data from all three cohorts of the study, show that administration of PTC124 is associated with qualitative increases in muscle dystrophin expression and with reductions in serum creatine kinase values. These data were presented today at the World Muscle Society (WMS) International Congress in Taormina, Italy.

Patients with DMD are boys and young men who lack dystrophin, a protein that is critical to the structural stability of muscle fibers. This Phase 2 multi-site, open-label, dose-ranging clinical trial enrolled 38 boys with loss of dystrophin due to a nonsense mutation in the dystrophin gene. Participants also had substantially elevated serum creatine kinase levels due to the disease, and symptoms associated with DMD. Boys enrolled in the trial received 28 days of PTC124 treatment at one of three dose levels, with the primary endpoint of the trial being an increase in dystrophin expression in muscle. Pre- and post-treatment muscle biopsies and blood analyses to assess muscle-derived creatine kinase were available from all 38 patients.

An in vitro analysis demonstrated PTC124-induced dystrophin expression in cultured muscle cells from all 35 (100%) of the boys with samples evaluable in this analysis. The in vivo data indicated that, across all three dose levels of PTC124, 18/38 (47%) of patients demonstrated visible improvement in the staining for dystrophin from muscle biopsies. Response did not appear to be dependent on type of nonsense mutation.

Blood levels of muscle-derived creatine kinase were also measured as assessments of muscle integrity. Statistically significant reductions in the concentrations of muscle-derived creatine kinase were observed during PTC124 treatment. In addition, several parents and teachers reported that boys participating in the study had improvements in terms of greater activity level and increased endurance during the study duration.

“We are very encouraged by these results, which show improvements in critical biomarkers of DMD,” said presenter and study investigator, Carsten Bönnemann, M.D., Assistant Professor Neurology and Pediatrics, Children's Hospital of Philadelphia and University of Pennsylvania School of Medicine and Co-Director of the Neuromuscular Program, Children's Hospital of Philadelphia. “The combined in vitro and in vivo evidence of enhanced dystrophin expression and reduced muscle fragility offer signals of pharmacological activity that we hope to translate into potential clinical benefit for patients with DMD.”

“Coupled with the emerging safety profile of PTC124, these data provide the impetus for moving forward rapidly to initiate longer-term studies for boys with DMD,” said Langdon Miller, M.D., Chief Medical Officer of PTC. “We are actively working with our clinical investigators and the regulatory agencies to finalize plans for additional clinical trials and we look forward to commencing these studies in the coming months.”

Stuart W. Peltz, Ph.D., President and Chief Executive Officer of PTC Therapeutics added, “These results, combined with the data presented earlier this month at the Child Neurology Society meeting and North American Cystic Fibrosis Conference, further support our belief that PTC124 represents a paradigm shift in the treatment of genetic disorders. Our future plans for PTC124 include the initiation of longer-term studies in DMD and cystic fibrosis (CF) as well as additional proof of concept studies in other indications. We hope that PTC124 will one day offer an improved treatment option for patients with nonsense-mediated DMD, CF, and a broad range of genetic disorders.”

About Duchenne Muscular Dystrophy
Duchenne muscular dystrophy (DMD) is a progressive muscle disorder that causes the loss of both muscle function and independence. DMD is perhaps the most prevalent of the muscular dystrophies and is the most common lethal genetic disorder diagnosed during childhood today. Each year, approximately 20,000 children worldwide are born with DMD (one of every 3,500 male children). More information regarding DMD is available through the Muscular Dystrophy Association (www.mdausa.org) and the Parent Project Muscular Dystrophy (www.parentprojectmd.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. PTC is currently conducting Phase 2 clinical trials of PTC124 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 Fast-Track designations and 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 is 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 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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PTC THERAPEUTICS ANNOUNCES PHARMACOKINETIC AND SAFETY RESULTS FROM PHASE 2 STUDY OF PTC124 IN DUCHENNE MUSCULAR DYSTROPHY

- Data Presented at 36th Child Neurology Society Annual Meeting -

SOUTH PLAINFIELD, NJ – October 11, 2007 - PTC Therapeutics, Inc. (PTC), a biopharmaceutical company focused on the discovery, development and commercialization of small-molecule drugs targeting post-transcriptional control mechanisms, today announced pharmacokinetic and safety data from a Phase 2 clinical trial of PTC124 in patients with Duchenne muscular dystrophy (DMD) due to a nonsense mutation. The results, which include data from the third and final cohort of the study, show that treatment with PTC124 appeared well tolerated at all three dose levels and target plasma concentrations were achieved at the mid- and high-dose levels. These data were presented today at the 36th Annual Meeting of the Child Neurology Society (CNS) in Quebec City, Canada.

In the study, patients received 28 days of PTC124 treatment at one of three dose levels. All clinical trial participants are boys with a nonsense mutation in the dystrophin gene, substantially elevated serum creatine kinase levels, and symptoms associated with DMD. The analysis presented today showed that PTC124 appeared well tolerated among the 38 boys included in the study. Adverse events were infrequent, mild to moderate in severity, and did not result in therapy interruptions or discontinuations. There were no concerns based on physical examinations, vital sign measurements, electrocardiograms or laboratory parameters. Compliance with PTC124 treatment was excellent at all three dose levels. Target plasma concentrations associated with activity in a preclinical model of DMD were achieved at the mid- and high-dose levels.

“DMD is a disorder with a significant need for better treatment options and we are encouraged by the 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, OH, who presented the data today at CNS and is one of the trial's lead investigators. “Based on the findings from this study, we believe that the safety profile of PTC124 supports continued testing in longer-term studies”

“These results add to the growing body of safety data for PTC124, which has now been evaluated in more than 150 subjects, including patients with both DMD and cystic fibrosis. The safety profile has consistently shown that PTC124 appears well tolerated,” said Langdon Miller, M.D., Chief Medical Officer of PTC. “We are looking forward to presenting additional activity data from this study next week at the World Muscle Society meeting in Italy.”

About Duchenne Muscular Dystrophy
Duchenne muscular dystrophy (DMD) is a progressive muscle disorder that causes the loss of both muscle function and independence. DMD is perhaps the most prevalent of the muscular dystrophies and is the most common lethal genetic disorder diagnosed during childhood today. Each year, approximately 20,000 children worldwide are born with DMD (one of every 3,500 male children). More information regarding DMD is available through the Muscular Dystrophy Association (www.mdausa.org) and the Parent Project Muscular Dystrophy (www.parentprojectmd.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. PTC is currently conducting Phase 2 clinical trials of PTC124 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 Fast-Track designations and 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 is 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 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, CV Therapeutics and Schering-Plough. For more information, visit the company’s website, www.ptcbio.com.

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PTC THERAPEUTICS ANNOUNCES ENCOURAGING ADDITIONAL PHASE 2 RESULTS OF PTC124 IN CYSTIC FIBROSIS

- New pediatric data presented at 21st North American Cystic Fibrosis Conference confirm previous findings in adult population -

SOUTH PLAINFIELD, NJ – October 5, 2007 - PTC Therapeutics, Inc. (PTC), a biopharmaceutical company focused on the discovery, development and commercialization of small-molecule drugs targeting post-transcriptional control mechanisms, today announced encouraging data from a Phase 2 clinical trial of PTC124 in pediatric patients with cystic fibrosis (CF) due to a nonsense mutation. These pediatric results and additional information emerging from long-term studies support the existing data from prior short-term studies in adult CF patients. These studies show that treatment with PTC124 results in statistically significant improvements in a measure of the function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein. These data were highlighted today in a plenary session entitled “CF Drug Development: What’s New?” given by Dr. Felix Ratjen, University of Toronto Professor of Pediatrics and Respiratory Medicine Division Chief, at the 21st North American Cystic Fibrosis Conference in Anaheim, California.

Patients with CF lack the CFTR protein, a chloride channel that maintains proper hydration of epithelial cells in the lung, pancreas, and liver. PTC has completed multi-site, open-label, dose-ranging Phase 2 clinical trials in adult CF patients to determine whether PTC124 can induce production of active CFTR protein. Studies in the U.S. and Israel evaluated nasal transepithelial potential difference (TEPD) as a surrogate for CFTR protein production in adult CF patients. Across the two studies, at both PTC124 dose levels tested, TEPD assessments showed statistically significant (p<0.03) improvements of mean CFTR-dependent chloride secretion in the airways.

PTC is currently conducting a third, open-label, dose-ranging Phase 2 clinical trial in pediatric CF patients at l’Hôpital Necker-Enfants Malade, Paris, France to determine whether PTC124 can induce production of active CFTR protein. In the trial, patients receive two sequential two-week courses of treatment. Patients have been randomized to receive either a low or high dose of PTC124 followed by two weeks of rest and then are crossed over to the other dose level for an additional two weeks of therapy. Eleven patients have completed the study and data from these patients were available for inclusion in the initial analysis. Across both dose levels, statistically significant improvements (p<0.05) were seen in CFTR chloride-channel function as measured by TEPD.

“Our initial observations in a pediatric population confirm the findings from the previous studies in older CF patients,” said Isabelle Sermet-Gaudelus, M.D., Ph.D., principal investigator at l’Hôpital Necker-Enfants Malade, Paris, France. “Normalization of CFTR-mediated chloride secretion was observed in several of the children, indicating that PTC124 continues to demonstrate significant potential as a treatment for patients with CF. Based on the enthusiasm generated by these data, we have recently added two new study sites in Belgium in order to expand the evaluation of PTC124 across a larger pediatric population.”

Eitan Kerem, M.D., Head of Pediatrics and the CF Center at the Hadassah University Hospital in Mount Scopus, Jerusalem also commented on longer-term studies that he has been leading in Israel. “Based on the positive results we observed during our initial study with two-week treatment periods, we have analyzed preliminary data from a three-month extension study evaluating the longer-term effect of PTC124 in patients with nonsense-mutation-mediated CF. We have seen encouraging evidence of sustained CFTR chloride-channel function and improvements in symptoms of CF, such as coughing, which we believe may be predictive of longer-term clinical benefit. We look forward to presenting the full data from this trial next year.”

“We are very pleased to see the evidence of drug activity reported at last year’s North American Cystic Fibrosis Conference reproduced by additional investigators in a pediatric population,” said Langdon Miller, M.D., Chief Medical Officer of PTC. “We are also encouraged by the findings of the Israeli three-month study. We believe these confirmatory results, coupled with supportive safety data in more than 50 patients participating in the Phase 2 trial program, can lead to initiation of longer-term trials to evaluate the clinical benefit of PTC124 in patients with CF.”

ABOUT CYSTIC FIBROSIS
Cystic fibrosis (CF) is among the most common life-threatening genetic disorders worldwide. According to the Cystic Fibrosis Foundation, CF affects approximately 30,000 adults and children in the United States and, according to the European Cystic Fibrosis Foundation, it affects a similar number of patients in Europe. CF occurs in approximately one of every 3,500 live births, with approximately 1,000 new cases diagnosed each year in the United States. There is a commercially available genetic test to determine if a patient’s CF is caused by a nonsense mutation and it is estimated that nonsense mutations are the cause of CF in approximately 10% of patients in the United States. There is currently no available therapy to correct defective CFTR production and function. Instead, available treatments for CF are designed to alleviate the symptoms of the disease. These treatments include chest physical therapy to clear the thick mucus from the lungs, antibiotics to treat lung infections and a mucus-thinning drug designed to reduce the number of lung infections and improve lung function. In addition, the majority of cystic fibrosis patients take pancreatic enzyme supplements to assist with food absorption in digestion. There is a significant unmet medical need for a treatment for the underlying cause of CF. More information regarding CF is available through the Cystic Fibrosis Foundation (www.cff.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. PTC is currently conducting Phase 2 clinical trials of PTC124 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 Fast-Track designations and 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 is 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 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 Celgene, Pfizer, CV Therapeutics and Schering-Plough.

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PTC THERAPEUTICS ANNOUNCES $20 MILLION
STRATEGIC INVESTMENT FROM CELGENE CORPORATION

- PTC Grants Celgene Option for Collaboration on Two Targets Utilizing GEMS Platform -

SOUTH PLAINFIELD, NJ – September 13, 2007 - PTC Therapeutics, Inc. (PTC), a biopharmaceutical company focused on the discovery, development and commercialization of small-molecule drugs targeting post-transcriptional control mechanisms, today announced that that Celgene Corporation (NASDAQ: CELG) will make a $20 million equity investment in PTC. At the same time, PTC will grant Celgene an option for an exclusive research and option agreement on two oncology targets for the development of orally bioavailable small molecules through the application of PTC’s GEMS (Gene Expression Modulation by Small-molecules) technology.

Under the terms of the research and option agreement, if the Celgene option is exercised, PTC may receive funding for research efforts and earn substantial milestone payments per target for achieving certain discovery, development, regulatory, and commercial objectives. Celgene will receive exclusive worldwide rights and pay PTC royalties on worldwide net sales of any products resulting from this collaboration.

“Celgene is widely recognized for its scientific innovation and commercial success in developing novel oral solutions for areas of high unmet medical need. We are delighted to welcome them as an investor,” said Stuart Peltz, Ph.D., President and CEO of PTC Therapeutics. “We have developed an innovative approach to drug discovery in our GEMS technology and have demonstrated its potential through our multiple internal programs and collaborations. This significant support from Celgene will strengthen our continuing efforts to develop and commercialize products based on our GEMS technology.”

"We are pleased to make this investment in PTC Therapeutics, a demonstrated leader in the discovery and development of small molecules targeting RNA biology," said Sol Barer, Ph.D., Chairman and Chief Executive Officer of Celgene. "This investment, combined with the research option, enables Celgene to participate with PTC in the development of innovative therapies."

ABOUT GEMS
GEMS is PTC’s novel and proprietary technology platform for the identification of small-molecules that modulate post-transcriptional control mechanisms. Compounds identified through the GEMS technology target processes that act through the untranslated regions (UTRs) of messenger RNA (mRNA) molecules. PTC has successfully employed the GEMS technology in drug discovery programs in oncology, infectious diseases, cardiovascular diseases, and neuromuscular disorders.

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, CV Therapeutics and Schering-Plough. For more information, visit the company’s website, www.ptcbio.com.

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PTC THERAPEUTICS APPOINTS THERESA NATALICCHIO AS SENIOR VICE PRESIDENT OF MARKETING AND SALES

SOUTH PLAINFIELD, NJ – August 2, 2007 - PTC Therapeutics, Inc. (PTC), a biopharmaceutical company focused on the discovery, development and commercialization of small-molecule drugs targeting post-transcriptional control mechanisms, today announced that Theresa Natalicchio has been appointed as Senior Vice President of Marketing and Sales. In this role, she will be responsible for all commercialization aspects of PTC’s programs.

“We are excited to welcome Theresa to our management team,” said Stuart Peltz, Ph.D., President and CEO of PTC Therapeutics, Inc. “As we begin commercialization planning for our products, we look forward to leveraging Theresa’s extensive experience in the creation of successful product launch and marketing campaigns.”

“PTC’s drug discovery platform has the potential to address a broad range of genetic disorders, as well as many cancers and infectious diseases. I have been impressed with the company’s unique and innovative scientific focus and look forward to working with the PTC team to deliver these potential breakthrough treatments to patients who urgently need them,” commented Ms. Natalicchio.

Ms. Natalicchio comes to PTC with 25 years of product marketing experience at Pfizer. Inc. where she most recently held the position of Vice President of the Marketing Centers of Excellence overseeing consumer strategy, public relations, e-marketing, media, agency management, multicultural marketing and relationship marketing for Pfizer’s portfolio of US pharmaceutical products. Ms. Natalicchio began her career as a Market Research Analyst, advancing quickly into roles of increasing responsibility where she was primarily responsible for launch of blockbuster products such as Procardia XL®, Zithromax®, Zyrtec®, Viagra® and Lyrica®. Her previous roles have included U.S. and worldwide marketing, leading businesses focused on multiple therapeutic areas including arthritis, anti-infective, urology and women's health.

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, CV Therapeutics and Schering-Plough. For more information, visit the company’s website, www.ptcbio.com.

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PTC THERAPEUTICS ANNOUNCES $15.4 MILLION NIH RESEARCH GRANT FOR DUCHENNE MUSCULAR DYSTROPHY

Grant Extends Research Originally Supported by Parent Project Muscular Dystrophy

SOUTH PLAINFIELD, NJ – July 10, 2007 - PTC Therapeutics, Inc. (PTC), a biopharmaceutical company focused on the discovery, development and commercialization of small-molecule drugs targeting post-transcriptional control mechanisms, today announced that the National Institute of Neurological Disorders and Stroke and the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health (NIH) have awarded a $15.4 million, five-year U54 grant to fund further research into Duchenne muscular dystrophy (DMD). The grant award will support a research collaboration between PTC and the University of Pennsylvania School of Medicine and will build upon previous research and discovery work supported by Parent Project Muscular Dystrophy (PPMD) under an initiative known as Project Catalyst.

“This grant supports promising preclinical research on a number of targets believed to be medically relevant for DMD,” said H. Lee Sweeney, Ph.D., Professor and Chairman of the Department of Physiology at the University of Pennsylvania School of Medicine, Scientific Advisor to PPMD and principal investigator on this NIH grant. “Over the course of this grant, our goal is to have Project Catalyst compounds ready for advancement into clinical trials for patients with DMD.” Ellen Welch, Ph.D., Group Leader, Genetic Disorders at PTC and principal investigator for PTC on this grant, commented, “We are very excited about this grant award as it expands our ability to advance promising programs that we have been developing over the past several years.”

In 2003, PTC and PPMD initiated Project Catalyst, a research collaboration funded by PPMD to identify new treatments for patients with DMD. Project Catalyst leveraged PTC’s proprietary drug discovery technology called GEMS (Gene Expression Modulation by Small-molecules) to search for new potential drugs for DMD patients. The GEMS technology allows PTC to identify small molecules that up- or down-regulate the production of proteins. Utilizing the GEMS technology, promising lead compounds were identified for several targets believed to be medically relevant for DMD.

“We are extremely pleased that the initial progress of Project Catalyst will be extended through this NIH grant award,” stated Pat Furlong, Executive Director and Founder of Parent Project Muscular Dystrophy. “PTC and UPenn have demonstrated a long-standing commitment to research and clinical development for DMD and have made remarkable progress to date. The support of the NIH for Project Catalyst’s efforts offers great hope to all members of the DMD community.”

“This grant is a model of the type of translational research we seek to support,” said John D. Porter, Ph.D., Program Director, Neurogenetics Cluster and Technology Development Program, NIH National Institutes of Neurological Disorders and Stroke. “The strength of this collaboration is that it brings together advocacy groups, academia, industry, and government in order to make an impact on the treatment of rare disorders such as DMD.”

“We are honored to receive this award from the NIH in conjunction with our colleagues at UPenn,” stated Stuart W. Peltz, Ph.D., President and Chief Executive Officer of PTC Therapeutics. “These funds help support our commitment to developing multiple treatments for neuromuscular disorders. With PTC124 in Phase 2 trials for nonsense-mediated DMD, we are establishing the clinical and regulatory path for new treatments for DMD in which the Project Catalyst compounds can follow. Our goal is to help provide treatment options for all DMD patients.”

About Duchenne Muscular Dystrophy
Duchenne muscular dystrophy (DMD) is a progressive muscle disorder that causes the loss of both muscle function and independence. DMD is perhaps the most prevalent of the muscular dystrophies and is the most common lethal genetic disorder diagnosed during childhood today. Each year, approximately 20,000 children worldwide are born with DMD (one of every 3,500 male children). More information regarding DMD is available through the Muscular Dystrophy Association (www.mdausa.org) and the Parent Project Muscular Dystrophy (www.parentprojectmd.org).

About Parent Project Muscular Dystrophy
Parent Project Muscular Dystrophy (PPMD) is the largest nonprofit organization in the United States focused entirely on Duchenne muscular dystrophy. A small group of parents founded PPMD in 1994, and it has progressed into the world’s leading Duchenne muscular dystrophy organization. PPMD’s expertise is unparalleled, and they hold the highest ethical standards. They are the only organization taking a comprehensive approach in the fight against Duchenne—raising awareness, funding research, promoting advocacy, connecting the community, and broadening treatment options—and their efforts will ultimately lead to a cure.

About University of Pennsylvania School of Medicine
PENN Medicine is a $2.9 billion enterprise dedicated to the related missions of medical education, biomedical research, and high-quality patient care. PENN Medicine consists of the University of Pennsylvania School of Medicine (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System.

Penn's School of Medicine is ranked #2 in the nation for receipt of NIH research funds; and ranked #3 in the nation in U.S. News & World Report's most recent ranking of top research-oriented medical schools. Supporting 1,400 full-time faculty and 700 students, the School of Medicine is recognized worldwide for its superior education and training of the next generation of physician-scientists and leaders of academic medicine.

About the National Institute of Neurological Disorders and Stroke
The mission of National Institute of Neurological Disorders and Stroke (NINDS) is to reduce the burden of neurological disease - a burden borne by every age group, by every segment of society, by people all over the world.

The project described in this press release was supported by Grant Number U54NS058572 from the National Institute of Neurological Disorders and Stroke. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NINDS or the National Institute of Health.

About the National Institute of Arthritis and Musculoskeletal and Skin Diseases

The mission of the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), a part of the Department of Health and Human Services - National Institutes of Health, is to support research into the causes, treatment and prevention of arthritis and musculoskeletal and skin diseases; the training of basic and clinical scientists to carry out this research; and the dissemination of information on research progress in these diseases. For more information about NIAMS, call the information clearinghouse at (301) 495-4484 or (877) 22-NIAMS (free call) or visit the NIAMS Web site at http://www.niams.nih.gov.”

About PTC Therapeutics, Inc.
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, CV Therapeutics and Schering-Plough.

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PTC THERAPEUTICS APPOINTS MANAL MORSY, M.D., PH.D. AS VICE PRESIDENT OF REGULATORY AFFAIRS

SOUTH PLAINFIELD, NJ – June 26, 2007 - PTC Therapeutics, Inc. (PTC), a biopharmaceutical company focused on the discovery, development and commercialization of small-molecule drugs targeting post-transcriptional control mechanisms, today announced the appointment of Manal Morsy, M.D., Ph.D. as Vice President of Regulatory Affairs. In this role, Dr. Morsy will be responsible for leading PTC’s regulatory affairs activities for PTC124, PTC299, and future clinical programs.

“We are thrilled to welcome Dr. Morsy to our management team. Her broad experience in leading successful regulatory strategies will be invaluable to PTC as we continue the rapid advancement of our clinical programs,” said Stuart Peltz, Ph.D., President and Chief Executive Officer of PTC Therapeutics. “Dr. Morsy adds critical expertise in the regulatory arena as we expand our capabilities and move toward our goal of becoming a fully integrated biopharmaceutical company.”

“I am excited to join the PTC Therapeutics team. The Company’s clinical pipeline has tremendous potential to address significant areas of unmet medical need, and I am looking forward to guiding the regulatory strategies to advance the registration and commercialization plans for these novel and potentially life-changing compounds to patients,” commented Dr. Morsy.

Prior to joining PTC, Dr. Morsy spent three years at Tibotec / J&J, most recently serving as Senior Director, Global Regulatory Affairs. There she was responsible for global regulatory activities for the company’s pediatric development programs and the tuberculosis program. Previous to her tenure at Tibotec, Dr. Morsy served as Director of Worldwide Regulatory Affairs for Merck & Co., where she supported new regulatory filings in the US and abroad, as well as supplemental filings for previously approved products.

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, CV Therapeutics and Schering-Plough. For more information, please visit the Company’s website at www.ptcbio.com.


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PTC THERAPEUTICS PRESENTS PHASE 1 RESULTS OF ITS NOVEL VEGF INHIBITOR, PTC299, AT 43RD AMERICAN SOCIETY OF CLINICAL ONCOLOGY (ASCO) ANNUAL MEETING

-Company to Initiate Phase1b/2 Clinical Trial in Advanced Breast Cancer in 2007-

CHICAGO, IL and SOUTH PLAINFIELD, NJ – June 3, 2007 - PTC Therapeutics, Inc. (PTC), a biopharmaceutical company focused on the discovery and development of small-molecule drugs targeting post-transcriptional control mechanisms, today presented data from its Phase 1 single- and multiple-dose studies in healthy volunteers evaluating PTC299, its novel VEGF inhibitor. Data from these two safety and pharmacokinetic studies confirmed that PTC299 is well tolerated up to the maximum tested dose and, in the multiple-dose study, safely achieves the desired target plasma concentrations at all tested dose levels. PTC299 is a novel, orally bioavailable investigational drug discovered by PTC which selectively inhibits production of vascular endothelial growth factor (VEGF) in tumors.

“We are very encouraged by the results of these clinical studies which show that PTC299 is well tolerated at plasma concentrations associated with antiangiogenic and antitumor activity in preclinical models,” stated Langdon Miller, M.D., Chief Medical Officer at PTC Therapeutics, Inc. “Furthermore, these Phase 1 data appear consistent with our preclinical results that suggest PTC299 selectively inhibits pathological tumor-associated VEGF production while not affecting physiological VEGF production. It is notable that we did not see adverse events such as bleeding, hypertension, or proteinuria that have been associated with other VEGF inhibitors. Given the very high unmet medical need in oncology, we are committed to rapidly advancing clinical trials of PTC299 in patients with cancer.”

Data from these clinical trials were detailed in a poster entitled, “Phase 1 studies assessing the safety, PK, and VEGF-modulating effects of PTC299, a novel VEGF expression inhibitor” (Poster Number H9). The poster was presented on June 3rd at the Developmental Therapeutics: Molecular Therapeutics session of the 43rd Annual ASCO Meeting, being held from June 1-5, 2007, in Chicago, Illinois.

In the initial clinical study, 52 healthy volunteers received single doses up to 3 mg/kg of PTC299. In the subsequent multiple-dose study, 32 healthy volunteers received doses through 1.2 mg/kg/dose two times per day and 1.6 mg/kg/dose three times per day. Among these healthy volunteers, PTC299 was well tolerated, with no serious, dose-limiting, or definitively drug-related adverse events. All clinical adverse events were mild (Grade 1) or moderate (Grade 2) in severity and did not require any intervention. Pharmacokinetic data indicated dose-proportional increases in plasma exposures and the target trough plasma concentration was achieved and maintained at all dose levels in the multiple-dose study.

“The continued progress of PTC299 provides further validation of our novel GEMS technology which targets post-transcriptional control processes,” commented Stuart W. Peltz, Ph.D., President and CEO of PTC Therapeutics, Inc. “PTC299 selectively inhibited tumor VEGF production and tumor growth in preclinical studies. With a new mechanism that acts upstream of available antiangiogenic agents, PTC299 has demonstrated activity alone and in combination with hormonal, chemotherapeutic, and other antiangiogenic agents. These results position PTC299 as a potential therapy for a broad range of solid tumors.”

PTC plans to initiate a Phase 1b/2 clinical trial in patients with advanced breast cancer during the second half of 2007. This trial will be funded in part through a three-year, $2.2 million grant from the Department of Defense (DoD), which was awarded to PTC last year to fund both the preclinical and clinical development of PTC299 in breast cancer.

About Department of Defense Clinical Translational Research Award
The DoD Clinical Translational Research Award sponsors innovative preclinical and clinical/translational research that may result in substantial improvements over current approaches to breast cancer chemoprevention and therapy. As part of the Congressionally Directed Medical Research Programs, it administers funds for peer-reviewed research toward specific diseases and supports research that positively affects the health and well-being of Americans. For this grant (grant number W81XWH-06-1-0629), the U.S. Army Medical Research Acquisition Activity, 820 Chandler Street, Fort Detrick, MD 21702-5014 is the awarding and administering acquisitions office. The content of this press release does not necessarily reflect the position or the policy of the Government, and no official endorsement should be inferred.

About PTC299
PTC299 is a novel, orally administered small-molecule compound that inhibits the production of the protein vascular endothelial growth factor, or VEGF, in tumors. PTC discovered PTC299 through PTC’s proprietary GEMS (Gene Expression Modulation by Small-Molecules) technology by targeting the post-transcriptional processes that regulate VEGF formation. Overexpression of VEGF plays a key role in the growth of many types of cancers. PTC299 inhibits VEGF production through a mechanism that is distinct from other VEGF inhibitors and has potential application in the treatment of multiple solid tumor types. In September 2006, PTC announced that it had received a three-year, $2.2 million grant from the Department of Defense (DoD) to fund preclinical and translational clinical development of PTC299 as a potential treatment for breast cancer.

About GEMS
Gene Expression Modulation by Small-molecules (GEMS) is PTC’s novel and proprietary screening technology for the identification of small-molecules that modulate post-transcriptional control mechanisms. Compounds identified through the GEMS technology target processes that act through the untranslated regions (UTRs) of messenger RNA (mRNA) molecules. GEMS was the basis for the discovery of PTC299 and is being used in multiple ongoing drug discovery programs.

About PTC Therapeutics, Inc.
PTC is a biopharmaceutical company focused on the discovery and development 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, CV Therapeutics and Schering-Plough. For more information, please visit the Company’s website at www.ptcbio.com.

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PTC Therapeutics Announces Additional Positive Interim Phase 2 Results of PTC124 in Duchenne Muscular Dystrophy

Data Presented at 59th American Academy of Neurology Annual Meeting

BOSTON, MA and SOUTH PLAINFIELD, NJ – May 4, 2007 - PTC Therapeutics, Inc. (PTC), a biopharmaceutical company focused on the discovery and development of small-molecule drugs targeting post-transcriptional control processes, today announced positive interim data from a Phase 2 clinical trial of PTC124 in patients with Duchenne muscular dystrophy (DMD) due to a nonsense mutation. The results from the first two cohorts of the three-cohort study show that treatment with PTC124 was associated with increases in muscle dystrophin expression and reductions in serum creatinine kinase values in at least 50 percent of evaluable patients. These data were presented today at the 59th American Academy of Neurology (AAN) Annual Meeting.

Patients with DMD lack dystrophin, a protein that is critical to the structural stability of muscle fibers. This Phase 2 multi-site, open-label, dose-ranging clinical trial is evaluating muscle dystrophin expression in patients with nonsense-mutation-mediated DMD. Blood levels of muscle-derived creatine kinase are being measured as assessments of muscle integrity. PTC124 safety, compliance, and pharmacokinetics are also being evaluated.

“These data provide clinical evidence that PTC124 treatment may address the underlying cause of DMD,” said Dr. Richard Finkel, Director of the Neuromuscular Program, Children’s Hospital of Philadelphia, PA, who presented these results today at AAN as one of the trial’s lead investigators. “Development of PTC124 offers the potential for a new therapeutic option for patients with DMD due to a nonsense mutation.”

Langdon Miller, M.D., Chief Medical Officer of PTC, added, “We are very pleased with these additional pharmacologic proof-of-concept data from our short-term Phase 2 clinical trial of PTC124 in patients with DMD. Based on the growing body of Phase 2 clinical data, we plan to initiate longer-term clinical trials to evaluate the clinical benefit of PTC124 in patients with DMD.”

The Phase 2 clinical trial is being conducted at three sites in the United States: Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; and the University of Utah, Salt Lake City, Utah. In the study, patients have received 28 days of PTC124 treatment at one of three dose levels. All clinical trial participants are boys with a nonsense mutation in the dystrophin gene, substantially elevated serum creatine kinase levels, and symptoms associated with DMD. The analysis presented today includes data from 26 patients with DMD who received PTC124 at the low-dose and medium-dose levels. Completion of accrual and analysis of data from a higher dose level are ongoing.

The primary endpoint of the trial has been the proportion of patients having an increase in dystrophin expression in muscle during 28 days of treatment with PTC124. Pre- and post-treatment muscle biopsies were available from all 26 patients for analysis. In vitro treatment of patient muscle cells with PTC124 showed evidence of a dose-dependent increase in dystrophin expression in all of the evaluable patients. Preliminary review of the data indicate that, at both dose levels evaluated in this analysis, approximately half of the patients demonstrated visible improvement in the staining for muscle dystrophin in vivo. Overall, four of the six, or 67 percent, of patients treated at the lower dose level and 10 of the 20, or 50 percent, of patients treated at the medium dose level demonstrated an increase in the expression of dystrophin post-treatment. Response did not appear to be dependent on type of nonsense mutation.

Additionally, statistically significant reductions in the concentrations of muscle-derived creatine kinase levels in the blood were observed during PTC124 treatment. Several parents and teachers reported that boys participating in the study had improvements in terms of greater activity level and increased endurance during treatment. Individual subjects at both dose levels demonstrated some improvements in upper and lower muscle strength however in the overall analysis the magnitude of change was not statistically significant.

PTC124 was well tolerated among the 26 patients included in the study. Adverse events were infrequent, mild to moderate in severity, and did not result in therapy interruptions or discontinuations. There were no safety concerns based on physical examinations, vital sign measurements, electrocardiograms or laboratory parameters. Compliance with PTC124 treatment was excellent at both dose levels.

Stuart W. Peltz, Ph.D., President and Chief Executive Officer of PTC Therapeutics, stated, “In addition to the clinical proof-of-concept data we disclosed late last year, these new insights provide us with further evidence supporting the potential of PTC124 in genetic disorders due to a nonsense mutation. The findings in the DMD trials are consistent with the results observed in Phase 2 clinical trials of PTC124 in patients with cystic fibrosis and with preclinical results in the DMD mouse model that were recently published in Nature. We are eager to extend testing of this concept into other nonsense-mediated genetic disorders.”

About Duchenne Muscular Dystrophy
Duchenne muscular dystrophy (DMD) is a progressive muscle disorder that causes the loss of both muscle function and independence. DMD is perhaps the most prevalent of the muscular dystrophies and is the most common lethal genetic disorder diagnosed during childhood today. Each year, approximately 20,000 children worldwide are born with DMD (one of every 3,500 male children). More information regarding DMD is available through the Muscular Dystrophy Association (www.mdausa.org) and the Parent Project Muscular Dystrophy (www.parentprojectmd.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. PTC is currently conducting Phase 2 clinical trials of PTC124 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 Fast-Track designations and 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 Committee for Orphan Medicinal Products (COMP) of the European Medicines Agency (EMEA). PTC124’s development is 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 PTC Therapeutics, Inc.
PTC is a biopharmaceutical company focused on the discovery and development 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, CV Therapeutics and Schering-Plough.

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PTC Therapeutics Announces Promotion of Neil Almstead to Senior Vice President of Chemistry and CMC

SOUTH PLAINFIELD, NJ – May 2, 2007 - PTC Therapeutics, Inc. (PTC), a biopharmaceutical company focused on the discovery and development of orally administered, proprietary small-molecule drugs that target post-transcriptional control processes, today announced the promotion of Neil Almstead to Senior Vice President of Chemistry and CMC, Chemistry Manufacturing and Controls.

“Neil was one of the first ten employees at PTC,” commented Stuart Peltz, Ph.D., President and CEO of PTC Therapeutics, Inc. “He was instrumental in establishing our chemistry capabilities which now include medicinal chemistry, analytical chemistry, chemistry informatics and formulation. Neil has directed multiple successful lead optimization programs and has developed CMC and manufacturing capabilities to support PTC’s clinical programs. I am extremely pleased to announce Neil’s promotion and look forward to working with him through the next stage of PTC’s growth and development.”

“I am honored to be a part of a phenomenal team here at PTC,” said Dr. Almstead. “From our early drug discovery efforts through to the clinic, we have an excellent track record of accomplishments. I look forward to working with Stuart and my other colleagues on the further clinical development of PTC124 and PTC299 as well as advancing our numerous other programs.”

Dr. Almstead joined PTC from Procter & Gamble (P&G) where he was directly involved in the areas of inflammatory diseases and oncology. At P&G he was project leader for both the Matrix Metalloproteinase and Map kinase inhibitor projects. Dr. Almstead has coauthored more than 75 publications and patents pertaining to the design and synthesis of lead candidate compounds for genetic disorders, oncology and inflammatory diseases. After receiving his Ph.D. in Organic Chemistry from the University of Illinois at Urbana-Champaign under the direction of Professor Scott Denmark, Dr. Almstead was a postdoctoral associate at the University of Basel in Switzerland with Professor Bernd Giese.

About PTC Therapeutics, Inc.
PTC is a biopharmaceutical company focused on the discovery and development 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, CV Therapeutics, and Schering-Plough.

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Targeting Specific Mutations Reveals Promising New Approach to Treating Genetic Disorders; Preclinical Data Published in Nature

PTC124 Targets Nonsense Mutations; Addresses Underlying Cause of Genetic Disorders and Restores Protein Function

South Plainfield, N.J., April 23, 2007 — New preclinical data published online in the current edition of the journal Nature show that PTC124, an investigational new drug designed to bypass nonsense mutations, was efficacious in a preclinical model of Duchenne muscular dystrophy (DMD). It is estimated that approximately 13 percent of the cases of DMD are due to nonsense mutations. PTC Therapeutics, Inc., which discovered and is developing PTC124, has catalogued over 1,800 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%).

“We are pleased that the Nature paper offers an opportunity for us to describe our novel approach to regulating post-transcriptional control processes” said Stuart W. Peltz, Ph.D., President and Chief Executive Officer of PTC Therapeutics. “As these preclinical data demonstrate, the broad potential of PTC124 lies in its specificity and unique mechanism of action, which has the potential to address the underlying cause of a broad range of genetic disorders due to nonsense mutations.”

Dr. Peltz continued, “In addition to the ongoing Phase 2 clinical trials of PTC124 in cystic fibrosis and Duchenne muscular dystrophy, we are evaluating PTC124 in a number of additional genetic disorders.”

Post-transcriptional control processes are the cellular regulatory events that take place after an RNA molecule is copied from DNA. These processes are critical to proper cellular function and provide an opportunity for therapeutic intervention through the modulation of protein levels.

Genetic disorders, such as DMD and cystic fibrosis (CF) are caused by genetic alterations, known as mutations. By targeting a specific type of genetic alteration – nonsense mutations – PTC124 bypasses the defect and leads to the restoration of a functional protein. The Nature paper highlights the data obtained from PTC’s work in a mouse model of DMD in which a nonsense mutation precludes the production of dystrophin. Loss of functional dystrophin, an important muscle protein involved in maintaining the strength of muscle fibers, results in DMD. The data demonstrate that PTC124 allows dystrophin to be made in cells in which it was previously absent, to be delivered to the proper cellular location, and to induce restoration of muscle function. In addition to the studies described in the Nature paper, PTC has demonstrated in preclinical studies that PTC124 restores the presence of the missing protein in CF caused by nonsense mutations. Similar to the effect in DMD, PTC124 induces production of CFTR (the missing protein in CF).

The paper entitled, "PTC124 targets genetic disorders caused by nonsense mutations" is available in an advanced online publication of Nature on Sunday, April 22nd (www.nature.com). This publication is the result of collaborative efforts between PTC Therapeutics, the University of Pennsylvania School of Medicine, and the University of Massachusetts Medical School.

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 introduce premature stop codons in RNA, which halt the translation process, producing a shortened, non-functional protein. PTC124 has demonstrated activity in preclinical genetic disease models harboring nonsense mutations, allowing the readthrough of premature stop codons and the restoration of the production of full-length, functional proteins. 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 readthrough of normal stop codons. PTC is currently conducting Phase 2 clinical trials of PTC124 in nonsense-mutation-mediated cystic fibrosis and Duchenne muscular dystrophy.

The FDA has granted PTC124 Fast-Track designations and Orphan Drug designations for the treatment of CF and DMD due to nonsense mutations. PTC124’s development is 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), the National Institutes of Health, and by General Clinical Research Center grants from the National Center for Research Resources (NCRR).

About PTC Therapeutics, Inc.
PTC is a biopharmaceutical company focused on the discovery and development 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, CV Therapeutics, and Schering-Plough.

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PTC Therapeutics Withdraws IPO Registration Statement

South Plainfield, N.J., April 20, 2007 - PTC Therapeutics, Inc., announced today that it has withdrawn its S-1 registration statement, previously filed with the Securities and Exchange Commission (SEC).

“Since we originally filed our S-1 last year, PTC has enjoyed significant business development successes which have put us in a strong financial position,” said Stuart W. Peltz, Ph.D., President and Chief Executive Officer of PTC Therapeutics. “Given that we have sufficient capital to meet our planned needs and the fact that we expect important clinical trial results within the next six months, we have decided to postpone our IPO.”

Dr. Peltz continued, “Our collaborations with Pfizer, CV Therapeutics and Schering-Plough have allowed us to secure a total of $42M in up-front payments. In addition, we have been awarded more than $20 million in research grants and government contracts to fund our growing pipeline. With three Phase 2 studies ongoing in genetic disorders for our most advanced program, PTC124, and with our second most advanced program, PTC299, about to enter Phase 1b clinical development in breast cancer, we are excited about the coming year.”

About PTC Therapeutics, Inc.
PTC is a biopharmaceutical company focused on the discovery and development 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, CV Therapeutics, and Schering-Plough.

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PTC Therapeutics Announces Strategic Drug Discovery Collaboration with Pfizer Utilizing PTC’s GEMS Technology Platform

SOUTH PLAINFIELD, N.J., January 8, 2007 – PTC Therapeutics, Inc (PTC) announced today an exclusive research collaboration and licensing agreement with Pfizer Inc for the development of pharmaceuticals through the application of PTC’s GEMS (Gene Expression Modulation by Small-molecules) technology. Under the terms of the agreement Pfizer has made an initial upfront payment of $10M, will purchase an equity stake of $10M subject to certain closing conditions, and will provide supportive funding for PTC’s research efforts. At Pfizer’s option, the collaboration may include up to 10 targets and PTC could earn up to $121M in milestones per target based on the achievement of certain development, regulatory, and commercial goals. Pfizer will receive exclusive worldwide rights and pay PTC royalties on worldwide net sales of any products resulting from this collaboration.

“We are very pleased with Pfizer’s significant commitment to our scientific approach,” said Stuart Peltz, Ph.D., President and CEO of PTC Therapeutics. “We have demonstrated the potential of the GEMS technology through our multiple internal programs and collaborations based on GEMS and believe this collaboration with Pfizer will broaden the applicability of the technology into new areas of high unmet medical need.”

GEMS is PTC’s novel and proprietary technology platform for the identification of small-molecules that modulate post-transcriptional control mechanisms. PTC has successfully employed the GEMS technology in drug discovery programs in oncology, infectious diseases, cardiovascular diseases, and neuromuscular disorders. PTC’s most advanced compound identified through the GEMS technology is PTC299, an orally-administered small molecule designed to inhibit the production of vascular endothelial growth factor (VEGF), which functions through a mechanism that is distinct from other VEGF inhibitors. PTC299 is currently in Phase 1 clinical trials.

About PTC

PTC is a biopharmaceutical company focused on the discovery and development of orally administered, proprietary small-molecule drugs that target post-t-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 has assembled proprietary technologies and extensive knowledge of post-transcriptional control processes that it applies in its drug discovery and development activities. PTC’s current pipeline of clinical and preclinical product candidates addresses multiple indications, including genetic disorders, oncology, and infectious diseases. 

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