EGFR tyrosine kinase inhibitor ZZC4 overcomes acquired resistance to gefitinib

Abstract

Despite the tremendous progress of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) development, acquired resistance mechanisms have limited their efficacy in treating non-small cell lung cancer (NSCLC). To overcome these limitations, novel EGFR-TKIs are needed. In our previous study, we presented ZZC4 as a potent EGFR-TKI. In this study, we developed NSCLC cells resistant to EGFR-TKI gefitinib and osimertinib and assessed the effect and mechanism of action of ZZC4 on those cells. HCC827 cells were cultured with gefitinib in a concentration-escalation manner to achieve HCC827 gefitinib-resistant (HCC827-GR) cells after 6 months of treatment. Then, the effect of ZZC4 was assessed at the cellular and animal levels. To understand ZZC4's mechanism of action, the proteome alteration induced by ZZC4 on the resistant cell line was compared to the parental HCC827 cells using comparative proteomics. The result showed that gefitinib's IC₅₀ on HCC827 was 533 nM, approximately 80 times its IC₅₀ on normal cells (7.6 nM), confirming its resistance to HCC827 cells. The obtained resistant cells were treated with ZZC4, which potently suppressed the resistant cells' proliferation with an IC₅₀ of 0.1 nM. In tumor-bearing mice, ZZC4 also suppressed the growth of HCC827-GR cell tumors with an inhibition ratio of 82 % at ZZC4 4 mg/kg. Further, the proteomic analysis revealed that ZZC4 inhibited HCC827-GR cell growth by upregulating CDKN1B and downregulating CCNA2 and CHEK1. In conclusion, ZZC4 overcomes resistance to gefitinib by altering the cell cycle pathway.