ELX19

ELX19 is a first-in-class proteolysis-targeting chimera (PROTAC) designed to specifically degrade the embryonic transcription factor SIX1. SIX1 is an embryonic transcription factor that is typically absent or weakly expressed in adult tissues but is frequently reactivated in various cancers, including head-and-neck squamous cell carcinoma (HNSCC) and esophageal adenocarcinoma (EAC). Reactivation of SIX1 drives pro-tumorigenic effects such as increased proliferation, induction of epithelial-mesenchymal transition (EMT), and the development of an immunosuppressive tumor microenvironment. ELX19 utilizes a Von Hippel-Lindau (VHL) E3 ligase recruitment mechanism to induce the ubiquitination and subsequent proteasomal degradation of SIX1. Preclinical studies have demonstrated that ELX19 achieves efficient SIX1 degradation in the nanomolar to low micromolar range, leading to reduced tumor cell proliferation and increased apoptosis, particularly when used in combination with cisplatin.