Abstract 345: Development of a novel and direct peptide Helicon࣪ inhibitor of β-catenin-TCF interaction with in vivo validation of transcriptional modulation and anti-tumor activity

Abstract Wnt pathway mutations can be found in nearly all colorectal cancers and a significant number of cancers of the liver, breast, prostate, endometrium and lung, among others. β-catenin is a key signaling hub in the Wnt pathway. Activated nuclear β-catenin forms a complex with TCF/LEF (T-cell factor/lymphoid enhancer binding factor) and drives the transcription of genes essential for cancer cell proliferation, survival, and metabolism. Blocking the β-catenin-TCF/LEF interaction offers an attractive therapeutic strategy to treat a large population of patients with WNT pathway mutations. However, β-catenin is considered as an “undruggable” target because it lacks tractable hydrophobic pockets for small-molecule binding. To address this challenge, we have successfully discovered and developed Helicon࣪ peptides targeting the β-catenin-TCF/LEF interaction. Using this novel modality, linear peptides are locked in a helical structure via a proprietary tethering technology to yield macrocyclic stapled peptides. Our helicons exhibit picomolar β-catenin binding affinity and nanomolar anti-proliferative cell-based activity. Cells treated with lead helicons followed by unbiased RNAseq GSEA indicate that the WNT/β-catenin pathways represent the top downregulated transcriptional signatures after treatment. Furthermore, PRISM cell line screening of more than 900 cell lines reveals that the most sensitive lines are enriched with APC and CTNNB1 mutations. Mechanistically, helicon treatment reduces nuclear β-catenin and alters the levels of cyclin D2/D3 and p27 in the sensitive lines. In vivo, our helicons display favorable pharmacokinetic properties, broad tissue distribution, and potent anti-tumor effects. Taken together, our data demonstrate β-catenin-targeting Helicon࣪ peptides have the potential to become the next-generation class of therapeutics to treat cancers with defined genetic mutations. Citation Format: Yaguang Si, Brian White, Sarah Cappucci, Jessica Ramirez, Charles Ponthier, Erica Visness, Kevin Ling, Peicheng Du, Minjung Choi, Ty Thomson, Josue Alfaro-Lopez, Pieter Beerepoot, Sorabh Agarwal, Paula Ortet, Miroslaw Lech, Zhi Li, Voké Olokpa, Ivan Jewett, Daniel La, Lihua Yu, John McGee, Martin Tremblay, Jonathan Hurov, Greg Verdine. Development of a novel and direct peptide Helicon࣪ inhibitor of β-catenin-TCF interaction with in vivo validation of transcriptional modulation and anti-tumor activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 345.