Discovery of Rezatapopt (PC14586), a First-in-Class, Small-Molecule Reactivator of p53 Y220C Mutant in Development

p53 is a potent transcription factor that is crucial in regulating cellular responses to stress. Mutations in the TP53 gene are found in >50% of human cancers, predominantly occurring in the DNA-binding domain (amino acids 94–292). The Y220C mutation accounts for 1.8% of all of the TP53 mutations and produces a thermally unstable protein. Rezatapopt (also known as PC14586) is the first small-molecule p53 Y220C reactivator being evaluated in clinical trials. Rezatapopt was specifically designed to tightly bind to a pocket created by the TP53 Y220C mutation. By stabilization of the p53 protein structure, rezatapopt restores p53 tumor suppressor functions. In mouse models with established human tumor xenografts harboring the TP53 Y220C mutation, rezatapopt demonstrated tumor inhibition and regression at well-tolerated doses. In Phase 1 clinical trials, rezatapopt demonstrated a favorable safety profile within the efficacious dose range and showed single-agent efficacy in heavily pretreated patients with various TP53 Y220C mutant solid tumors.