Abstract 409: Targeted degradation of FAK and PYK2 in cancer

Abstract Focal adhesion kinase (FAK) and its paralog proline-rich tyrosine kinase 2 (PYK2) are non-receptor kinases that are critical in the initiation, progression, and metastasis of several cancers, including triple-negative breast cancer and pancreatic ductal adenocarcinoma. FAK and PYK2 are overexpressed in these cancers and have diverse activities in the cell, including functioning as kinases, serving as scaffolding proteins, and regulating transcriptional programs. Consequently, they have emerged as important drug targets in cancer. Despite the critical need to advance novel therapeutic approaches in triple-negative breast cancer and pancreatic ductal adenocarcinoma to improve survival rates, the development of selective agents to target FAK or PYK2 in isolation has remained challenging. In this study, we hypothesized that abolishing all functions of FAK and/or PYK2 using targeted degradation approaches would be advantageous over small molecule kinase inhibitors. Building on our prior work to develop FAK-selective heterobifunctional degraders known as PROTACs, we endeavored on a campaign to develop PYK2-selective and FAK/PYK2-dual targeting PROTACs. We synthesized a series of PROTACs that engage FAK and/or PYK2 and recruit an E3 ubiquitin ligase to achieve target protein degradation. These compounds, which vary in their kinase binding warheads, linkers, and E3 ubiquitin ligase binders, were evaluated through assays to measure target engagement in cells, protein levels using immunoblotting, selectivity using quantitative proteomics, and impact on phenotypes including 3D-spheroid viability and cell migration. This pipeline led to the identification of potent (< 250 nM) and selective degraders of PYK2 and FAK/PYK2 that rapidly (< 2 hours) diminish protein levels. These PROTACs require the ubiquitin-proteasome machinery to achieve degradation and display proteome-wide selectivity towards the intended kinases. In pancreatic cancer and breast cancer cell lines, degradation of both FAK/PYK2 led to significant reductions in 3D-spheroid viability and migration. These effects were improved compared to FAK or PYK2 inhibition or degradation in isolation. In addition, targeted destruction of FAK, PYK2, or FAK/PYK2 led to substantially improved reductions in 3D-spheroid viability and migration compared to kinase inhibition, highlighting the importance of disabling the enzymatic and non-enzymatic roles of FAK and PYK2. Together, our work establishes a chemical toolbox to degrade FAK, PYK2, or FAK/PYK2 to uncover FAK and PYK2 shared and distinct roles and advances targeted degradation of these kinases as a potential therapeutic approach in cancer. Citation Format: Christina C. Kuismi, Yuan Jiang, Baishan Jiang, Behnam Nabet. Targeted degradation of FAK and PYK2 in cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 409.