Covalent Recruitment of NEDD4 for Targeted Protein Degradation: Rational Design of Small Molecular Degraders

Targeted protein degradation (TPD) has emerged as a promising therapeutic strategy for treating various diseases. However, current small molecule degraders predominantly rely on a limited set of E3 ubiquitin ligases, such as CRBN and VHL, which restricts their applications. Here, we report that incorporation of the 2<i>H</i>-azirine chemical handle into the EGFR^{L858R/T790M/C797S} inhibitor induced remarkable degradation of the targeted protein. Proteomic profiling and functional validation confirmed that the NEDD4 E3 ligase was covalently recruited by 2<i>H</i>-azirine through engagement of C1286 residue, facilitating target degradation. Furthermore, the 2<i>H</i>-azirine moiety demonstrated versatility by acting as a small molecular degrader when conjugated to various ligands, effectively mediating the degradation of CDK4, PDE5, BTK and Brd4. More importantly, using the identical protein ligand scaffold, we demonstrated that the 2<i>H</i>-azirine based probe can degrade proteins resistant to degradation by CRBN or VHL recruitment. This approach provides a rational strategy for developing novel small molecular degraders that target alternative E3 ubiquitin ligases. Notably, these degraders significantly outperformed their parent kinase inhibitor in suppressing cancer cell growth.