Abstract 3022: Novel hydrocarbon stapled peptide inhibitors suppresses β-catenin dependent cancer growth and immunomodulates colorectal tumors

Mutations in several components of the canonical Wnt pathway function as drivers in a range of common solid tumor cancers, including about 90% of sporadic colorectal cancers (CRCs), the third most common cancer in the US. In particular, activation of β-catenin (β-cat), a key Wnt signaling component, can initiate tumorigenesis in the intestine and promote cancer stem cell metastasis6,7. As such, targeting the Wnt pathway is an attractive approach to the development of cancer therapeutics. However, Wnt inhibitors tested to date, including those that disrupt β-cat activity, have either had limited efficacy or unacceptable side effect profiles1. Here, we developed a potent and robust, selective lead compound targeting oncogenic Wnt activity by disrupting the highly specific interaction of β-cat with its co-activators BCL9/B9L, which has been shown to abrogate transactivation. By using hydrocarbon stapled peptide technology and an acutely sensitive high throughput biochemical screening assay, we have identified several promising peptides that possess a strong pharmacokinetic profile. These peptides (i) exhibit robust activity in mouse models; (ii) inhibit cancer cell proliferation, metastasis, and stem cell progression; and (iii) modulate the immune microenvironment, demonstrating the feasibility of such peptide development and selection. Synergy is demonstrated between the stapled peptides and anti-PD1 antibodies, which has significant implications for combination therapy with commercial immune checkpoint blockers that have become standard of care for second-line melanoma treatment. These peptides represent a promising new potential therapeutic class for patients with CRC, for which traditional chemotherapy and targeted inhibitors have had limited therapeutic success. Citation Format: David Zhu, Joy Jin. Novel hydrocarbon stapled peptide inhibitors suppresses β-catenin dependent cancer growth and immunomodulates colorectal tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3022. doi:10.1158/1538-7445.AM2017-3022