PTI-129

PTI-129 is a **preclinical, once-daily, oral small molecule** developed by **Proteostasis Therapeutics** as a **modulator of the unfolded protein response**. It was designed to enhance the adaptive branches of the UPR and reduce accumulation of misfolded proteins, with an initial therapeutic focus on **cystic fibrosis** and other disorders driven by defective protein folding and processing. The compound was also reported in vitro to reduce viral protein production in host cells in exploratory work related to **COVID-19**, but it remained a **preclinical research-stage asset** and had not advanced to clinical development based on the provided information.