Synergistic Antitumor Activity of Combination Therapy with a MET TKI Vabametkib and a Third-Generation EGFR TKI Lazertinib in MET-Amplified EGFR-Mutant NSCLC

Purpose: Third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKIs) improved outcomes in EGFR-mutant non-small cell lung cancer (NSCLC); however, the subsequent development of resistance emphasizes the necessity of overcoming this therapeutic limitation. MET amplification is one of the major resistance mechanism in EGFR-mutant NSCLC, bypassing EGFR inhibition by activating cell survival, proliferation, and metastasis. Combining MET- and EGFR-TKIs is thus emerging as a promising therapeutic strategy to overcome resistance to EGFR TKIs. Materials and Methods: This study aimed to investigate the combination of the selective MET TKI vabametkib and a third-generation EGFR TKI lazertinib in MET-amplified EGFR TKI resistance models. Inhibition of downstream signaling and cell proliferation by vabametkib plus lazertinib were evaluated in osimertinib-resistance NSCLC cell lines (HCC827-AR) and patient-derived organoid (YUO-010) by western blot and Cell Titer-Glo assay. Results: In vitro studies demonstrated that vabametkib plus lazertinib synergistically inhibited EGFR/MET phosphorylation, leading to markedly enhanced anti-proliferative effects through downstream PI3K/AKT and MAPK pathway blockade. To investigate the antitumor effects in in vivo, we employed two patient-derived xenograft (PDX) models (YHIM-1035(1) and YHIM-1053) harboring MET amplification, as characterized by whole-exome sequencing or droplet digital PCR (ddPCR). Consistent with the in vitro findings, treatment with vabametkib plus lazertinib produced pronounced suppression of tumor growth in both models through a synergistic mechanism. Conclusion: These findings establish vabametkib plus lazertinib as a promising strategy for MET-amplified NSCLC, currently under evaluation in an ongoing phase II clinical trial (NCT05541822).