Development of Novel Silicon-Based Hydrophobic Tags (SiHyT) for Targeted Proteins Degradation

Recent advances in targeted protein degradation (TPD) have propelled it to the forefront of small molecular drug discovery. Among these, hydrophobic tagging (HyT) strategies have garnered significant interest. Carbon-based hydrophobic tags have been recognized as effective Hyts for degrading a variety of target proteins. In this study, we introduce a novel class of potential EGFR degraders for the first time, which combine Gefitinib with silicon-based hydrophobic tags (SiHyT). The most promising candidate, degrader 7, which links Gefitinib to a simple TBDPS silyl ether, has shown efficacy in degrading mutant EGFRs via the ubiquitin-proteosome system (UPS) both in vitro and in vivo. Notably, degrader 7 exhibits enhanced oral bioavailability owing to its superior metabolic stability compared to traditional carbon-based Hyts. Mechanistically, it was revealed that degrader 7 disrupts EGFR stability by dissociating the EGFR-HSP90 complex and recruiting E3 ligase, RNF149. More importantly, the potent and selective PD-L1 and BTK degraders were discovered successfully by utilizing the SiHyT strategy. The development of these innovative SiHyT compounds could broaden the repertoire of HyTs, enhancing the future design of TPD agents.