Abstract 5940: JAB-30355: A highly potent, orally bioavailable p53-Y220C reactivator

Abstract Background: As a key tumor suppressor, p53 precisely regulates cellular events such as cell cycle arrest, apoptosis, senescence, and DNA repair under physiological conditions. In 50-60% of human cancers, TP53 gene is mutated. The TP53 Y220C is a hotspot loss-of-function mutation occurring in around 1% of solid tumors. Application of p53-Y220C reactivator for restoration of p53 function represents a promising treatment strategy for patients with this mutation. Methods: The Induced Allosteric Drug Discovery Platform (IADDP), which integrates medicinal chemistry, biochemical and biophysical studies, and computational techniques, was applied for the development of JAB-30355. The proportion of p53-Y220C with wild-type protein-like structure after JAB-30355 treatment was determined by immunoprecipitation. Thermal shift assay was applied to assess the thermal stability of JAB-30355-reactivated p53-Y220C protein. DNA binding assay was developed to evaluate the in vitro DNA binding activity. p53-luciferase reporter system was developed to evaluate the cellular transcriptional activity. qPCR and Western blotting were performed to evaluate the transcriptional and translational levels of p53 downstream targets, respectively. CellTiter-Glo assay was performed to evaluate the inhibitory activity of JAB-30355 on the viability of tumor cell lines harboring wild-type or Y220C mutated TP53. In vivo PK-PD study was conducted to evaluate the relationship between JAB-30355 concentration and expression of p53 target genes. Multiple CDX and PDX mouse models harboring TP53 Y220C were used to evaluate the antitumor activity of JAB-30355. Results: Immunoprecipitation assay and thermal shift assay results demonstrated that JAB-30355 efficiently restored the wild-type p53-like structure and enhanced protein stability of p53-Y220C in a dose-dependent manner. In addition, JAB-30355 significantly enhanced the DNA binding activity of p53-Y220C and subsequently increased the expression of p53 target genes, such as CDKN1A, MDM2 and PUMA. JAB-30355 inhibited cell viability of multiple TP53 Y220C-mutated cancer cell lines with IC50s ranging from 0. 2 to 0. 7 μM, and exhibited good selectivity against TP53 wild-type cells. Overall, the in vitro data demonstrated that JAB-30355 is a potent and selective p53-Y220C reactivator. In vivo PK-PD study showed good correlation between JAB-30355 exposure and activation of p53 target genes. Furthermore, JAB-30355 exhibited dose-dependent anti-tumor activity, inducing tumor stasis or regression in multiple CDX and PDX models of ovarian cancer, pancreatic cancer, gastric cancer, and small cell lung cancer, with overall good tolerability. Conclusions: JAB-30355 is a highly potent, selective, and orally bioavailable p53-Y220C reactivator that will be tested in clinical space soon. Citation Format: Qian Zheng, Peng Wang, Chen Liang, Yao Li, Xin Sun, Amin Li, Wei Zhang, Wei Long, Yanping Wang. JAB-30355: A highly potent, orally bioavailable p53-Y220C reactivator abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 5940.