PN-105

PN-105 (also known as PTG-100) is an orally delivered, gut-restricted peptide antagonist of the α4β7 integrin. Developed by Protagonist Therapeutics, it was designed to treat inflammatory bowel diseases (IBD), such as ulcerative colitis, by blocking the interaction between α4β7 integrin on T-cells and MAdCAM-1 on the gut endothelium, thereby preventing the trafficking of inflammatory cells into the gastrointestinal tract. Unlike systemic biologics like vedolizumab, PN-105 is designed to act locally in the GI tract with minimal systemic exposure. Development of PN-105/PTG-100 was discontinued following a Phase 2 interim analysis in ulcerative colitis, with the company subsequently focusing on a more potent successor, PN-943.