Targeting mutant p53 aggregates in pancreatic cancer using an autophagy-targeting chimera

Abstract Protein aggregation is increasingly recognized as a fundamental feature of cancer biology, particularly in tumors experiencing chronic proteotoxic stress. TP53 is one of the most frequently mutated genes in human cancers, and many cancer-associated missense mutations promote p53 misfolding and amyloid-like aggregation. These aggregates impair wild-type tumor-suppressive functions while conferring oncogenic gain-of-function (GOF) activities that promote tumor progression and therapeutic resistance. Despite decades of effort, direct pharmacological targeting of mutant p53 has remained challenging because of its structural properties, including the lack of a readily druggable pocket, as well as its extensive mutational heterogeneity. Here, we employed the AUTOTAC platform to target mutant p53 aggregates by exploiting aggregation-associated conformational features characteristic of β -sheet-rich oligomers and protofibrillar aggregates. ATC-37 was designed by linking a methylene blue-derived amyloid-binding ligand, which preferentially recognizes β -sheet-rich protein aggregates, to an autophagy-targeting ligand (ATL) that allosterically activates the autophagy receptor p62/SQSTM1. This design enables engagement of amyloid-like mutant p53 aggregates and promotes their recruitment to autophagosomes. ATC-37 exhibits a dual, concentration-dependent mechanism of action. At low concentrations, it promotes autophagic degradation of mutant p53 aggregates and suppresses downstream GOF signaling. At higher concentrations, it induces p62-dependent sequestration of mutant p53 aggregates that exceeds autophagic capacity, leading to proteotoxic cell death. In a PANC-1 pancreatic cancer xenograft model, ATC-37 significantly inhibited tumor growth, reduced amyloid-like mutant p53 aggregates, and attenuated mutant p53-associated GOF programs. Importantly, ATC-37 also enhanced the response of mutant p53 pancreatic cancer cells to radiation, suggesting potential utility in combination with radiotherapy. These findings establish aggregation-state-directed AUTOTAC therapy as a conceptually innovative, mutation-agnostic strategy for targeting aggregation-prone mutant p53 and potentially other aggregation-prone oncoproteins.