Design, Synthesis, and Biological Evaluation of Novel Diaminopyrimidine Macrocycles as Fourth Generation Reversible EGFR Inhibitors That Overcome Clinical Resistance to Osimertinib Mediated by C797S Mutation

Overcoming clinical resistance to osimertinib mediated by the tertiary C797S mutation remains an unmet medical need. To date, there are no effective drugs that have been approved for patients who harbor EGFR^T790M/C797S mutations. Herein, we applied a structure-based drug design strategy to discover a series of potent and selective diaminopyrimidine macrocycles as novel EGFR^T790M/C797S inhibitors. The representative compound <b>21v</b> potently inhibited EGFR^{19del/T790M/C797S} and EGFR^{L858R/T790M/C797S} mutants with IC₅₀ values of 2.3 nM and 12.5 nM, respectively, and exhibited antiproliferative activity against Ba/F3-EGFR^{19del/T790M/C797S} and Ba/F3-EGFR^{L858R/T790M/C797S} cells with IC₅₀ values of 41 and 52 nM, respectively. Further, <b>21v</b> inhibited proliferation of the EGFR^{19del/T790M/C797S} mutant PC-9-OR NSCLC cell line with an IC₅₀ value of 56 nM and displayed selectivity over parental Ba/F3 and A431 cells. Moreover, <b>21v</b> exhibited antitumor efficacy in a Ba/F3-EGFR^{19del/T790M/C797S} xenograft model. This study provides a promising macrocyclic lead for anticancer drug discovery overcoming EGFR^C797S mutation mediated resistance in NSCLC patients.