Harnessing p53 for Proximity Killing

p53 tumor suppressor evolved as a critical player in navigating the response to environmental stresses such as DNA or oxidative damage and drives cell fate by governing life and death decisions. The p53 protein is encoded by the most commonly mutated gene in human cancers. TP53 gene mutations are associated with worse prognosis and refractory and relapsed disease. The most prevalent mutations are of the missense type and often result in disruption of the DNA-binding capacity and transcription activity. In healthy cells, p53 protein is tightly regulated by its E3 ubiquitin ligase, MDM2 (HDM2), its own transcription target. Mutant p53, therefore, escapes the regulation by the negative feedback loop and is often found upregulated in cancer cells. The efforts to exploit wild-type and mutant p53 for precision oncology have been ongoing in the last two decades yet have not been successful. A recently reported strategy to target TP53-mutant cancers leverages induced proximity, utilizing the high cellular abundance of mutant p53 as a scaffold to concentrate a small-molecule inhibitor against an essential survival protein. This strategy relies on the Regulated Induced Proximity TArgeting Chimera (RIPTAC). Given the recent FDA approval of the first chimeric drug, vepdegestrant, killing by proximity might turn out to be a promising medical advancement for precision oncology.