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Wnt signaling pathway mutations leading to constitutive activation of the driver oncogene β-catenin occur in at least 20% of all human cancers, but β-catenin itself has remained undruggable by traditional modalities. In order to inhibit the activity of β-catenin, we have developed conformationally hyperstabilized α-helical peptides (Helicons) that are cellularly permeable and bind directly to β-catenin in order to block its interaction with TCF family of transcription factors. Starting with a helical peptide derived from phage display, a combination of structural biology insights and medicinal chemistry optimization improved β-catenin binding of lead peptides to picomolar affinity. Cellular permeability was achieved by modification of physical properties as well as cyclization strategies to enforce helicity and manage backbone amide bonds. Helicons show excellent pharmacokinetic profiles suitable for intermittent dosing. β-catenin targeting helicons demonstrate on-target activity and potent inhibition of Wnt-driven tumor growth in vivo. Citation Format: Brian H. White, Yaguang Si, Sarah Cappucci, Zhi Li, Jessica D. Ramirez, Charles M. Ponthier, Erica Visness, Peicheng Du, Minjung Choi, Pieter C. Beerepoot, Paula C. Ortet, Ivan T. Jewett, Josue Alfaro-Lopez, Sorabh Agarwal, Daniel La, Aaron Fulgham, John H. McGee, Keith Orford, Jonathan B. Hurov, Martin R. Tremblay, Gregory L. Verdine. Discovery of a HeliconTM peptide inhibitor of the beta-catenin-TCF interaction with in vivo activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3094.

Genetic and epigenetic alterations in the Wnt signaling pathway leading to constitutive activation of the driver oncogene Β-catenin occur in at least 20% of all human cancers. We have developed conformationally hyperstabilized α-helical peptides (Helicons) that bind directly to Β-catenin with picomolar affinity and block its interaction with TCF transcription factors. We describe here the characterization of anti-tumor efficacy, pharmacodynamic biomarkers and mechanism of action using multiple in vivo patient-derived xenograft (PDX) models treated with Helicons. Helicon treatment leads to dose-dependent anti-tumor effects and durable regressions in PDX models from multiple indications with Wnt pathway activating mutations. Anti-tumor responses are seen in the presence of additional driver mutations, including KRAS and PIK3CA. RNA-sequencing and Gene Set Enrichment Analysis confirm Helicon treatment inhibits both Wnt/Β-catenin and MYC-regulated gene sets. Inhibiting Β-catenin-TCF interaction with Helicons represents a first-in-class therapeutic approach for the treatment of cancers resulting from aberrant transcriptional signaling via Β-catenin. Citation Format: YaGuang Si, Minjung Choi, Xinwei Han, Brian White, Ziyang Wu, Erica Visness, Pieter Beerepoot, Elizabeth Jaensch, Jessica Ramirez, Charles Ponthier, Xiaogang Han, Paula Ortet, Peicheng Du, Sorabh Agarwal, Mirek Lech, Aaron Fulgham, Sarah Cappucci, Zhi Li, John McGee, Lihua Yu, Martin Tremblay, Keith Orford, Gregory Verdine, Jonathan Hurov. Anti-tumor activity of Helicon inhibitors of Β-catenin-TCF interaction in patient-derived xenograft models. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4972.

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.