Synthesis and degradation effect of PROTACs targeting EGFR triple mutants.

Drug resistance caused by epidermal growth factor receptor (EGFR) mutation has significantly limited the clinical efficacy of EGFR tyrosine kinase inhibitors (EGFR-TKIs). In this study, we selected fourth-generation EGFR-TKIs (compounds A, B, and C) and EGFR-TKI D as ligands for EGFR, along with VHL-L1 and VHL-L2 as ligands for the E3 ligase, using acyl linkers to design novel PROTACs targeting EGFR triple mutants. We synthesized and evaluated compounds EP1-EP12. Among them, EP7, EP8, EP9, EP11 and EP12 exhibited potent antiproliferative activities against cells expressing EGFR mutants. Notably, EP9 and EP12 effectively induced the degradation of EGFR triple mutants (EGFRDel19/T790M/C797S and EGFRL858R/T790M/C797S) and significantly suppressed EGFR pathway signal transduction. Mechanism studies revealed that the degradation process requires the formation of ternary complexes and the ubiquitination of the EGFR protein, with the degradation being associated with lysosomal activity. In conclusion, compounds EP9 and EP12 were identified as potent degraders of EGFR triple mutants, offering new insights into the development of PROTACs for targeting these mutations.