R&D Overview

Oral, GI-restricted Peptides for GI Diseases

We are a clinical-stage biopharmaceutical company with a proprietary technology platform focused on discovering and developing peptide-based new chemical entities (NCEs) to address significant unmet medical needs. Our primary focus is on developing first-in-class oral peptide drugs that specifically target biological pathways also targeted by currently marketed injectable antibody drugs. Compared to injectable antibody drugs, our oral peptides offer targeted delivery to the gastrointestinal (GI) tissue compartment, potential for improved safety due to minimal exposure in the blood, improved convenience and compliance due to oral delivery, and the opportunity for earlier introduction of targeted therapy for inflammatory bowel disease (IBD). Our initial lead product candidates, PTG-100 and PTG-200, are based on this approach, and we believe they have the potential to transform the existing treatment paradigm for IBD, a GI disease consisting primarily of ulcerative colitis (UC) and Crohn’s disease (CD).

IBD is a chronic inflammatory disease with significant unmet medical need, which has created a large and growing market with an estimated 1.6 million patients in the United States in 2013. As of 2008, annual direct treatment costs for patients with IBD in the United States were estimated to exceed $6.3 billion, with indirect costs estimated to be an additional $5.5 billion. In 2015, GlobalData estimated that the UC markets reached approximately $4.6 billion across seven major markets and are expected to increase at a compound annual growth rate of approximately 1.7% to $5.5 billion by 2025. In 2012, GlobalData estimated that the CD markets reached approximately $3.2 billion across ten major markets and is expected to grow approximately 5% per year through 2022.

The current tumor necrosis factor-alpha (TNF-α) antibody drugs approved for moderate-to-severe IBD, Humira® and Remicade®, are both injectable. According to GlobalData, the 2013 sales for Humira and Remicade for IBD were $3.4 billion in the United States. Takeda Pharmaceuticals reported 2016 fiscal year sales for Entyvio® for IBD of ¥143.2 billion JPY (approximately US $1.3 billion). Like Entyvio, which is an injectable antibody drug, the oral peptide PTG-100 inhibits alpha-4-beta-7 integrin.

Approximately one third of IBD patients are nonresponders to TNF-α antibody drugs and approximately another 30% to 40% become refractory within the first year of treatment. Additionally, TNF-α antibody drugs may predispose patients to an increased risk of serious infection and the development of anti-drug antibodies (ADAs), which over time can cause loss of drug response. Thus, while available treatments exist for moderate-to-severe IBD, there continues to be a significant medical need for efficacious, safer, and convenient treatments.

Oral GI-Restricted Peptide Advantages Over Antibody Drugs

Oral Administration

  • Localized delivery with higher drug concentrations at site of active disease
  • No injection-site reactions
  • Greater convenience leads to increased compliance in patients

Potential for Improved Safety and Reduced Immunogenicity

  • Oral and GI-restricted delivery minimizes undesirable side effects associated with systemic exposure in the blood
  • Peptides can be cleared more quickly from systemic circulation
  • Likelihood of lower immunogenicity and reduces the risk of loss of response


  • Lower cost of production, storage, and shipment
  • Less complex manufacturing processes required

Other Peptide Assets

The genesis of our oral, GI-restricted peptide antagonists PTG-100 and PTG-200 is our proprietary technology platform. The platform in itself is not confined to oral delivery, or to GI disease targets or an antagonist approach. The platform is very diverse and can be potentially applied to discover and develop oral or injectable peptides via an antagonist or agonist/mimetic approach in both GI and non-GI diseases. A good example of this is our third asset PTG-300, an injectable hepcidin mimetic peptide discovered using the Company’s proprietary technology platform. PTG-300 is being developed as a potential treatment for patients with chronic iron overload in rare diseases such as beta-thalassemia.

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