Acquired resistance mechanisms to capmatinib, a MET inhibitor in MET-amplified non-small cell lung cancer cells

Abstract

Purpose: Amplified mesenchymal-epithelial transition factor, MET, is a receptor tyrosine kinase (RTK) that has been considered a druggable target in non-small cell lung cancer (NSCLC). Although multiple MET tyrosine kinase inhibitors (TKIs) are being actively developed for MET-driven NSCLC, the mechanisms of acquired resistance to MET-TKIs have not been elucidated. Capmatinib (INC280, Novartis) is a highly potent and selective small molecule MET-TKI. To understand the mechanisms of resistance to MET-TKIs and establish therapeutic strategies, we developed an in vitro model using capmatinib-resistant cell lines (EBC-CR1, CR2, and CR3) derived from the MET-amplified NSCLC cell line EBC-1. Methods: We established capmatinib-resistant NSCLC cell lines from the MET-amplified NSCLC cell line EBC-1 and identified alternative signaling pathways using 3mRNA sequencing and human phospho-RTK arrays. Copy number alterations were evaluated by quantitative PCR and cell proliferation assay

activation of RTKs and downstream effectors were compared between the parental cell line EBC-1 and the EBC-CR1, -CR2, and -CR3 resistant cell lines. Results: We found that epidermal growth factor (EGFR) mRNA expression and protein activation were increased in EBC-CR1–3 cells compared to EBC-1 cells. EBC-CR1 cells showed EGFR-dependent growth and sensitivity to afatinib, an irreversible EGFR TKI. EBC-CR2 cells, which overexpressed the EGFR-MET heterodimer, responded dramatically to the combination of capmatinib and the phosphoinositide-3 kinase catalytic subunit α (PIK3CA) inhibitor afatinib. In addition, EBC-CR3 cells, which had activated EGFR along with amplified PIK3CA, were sensitive to the combination of afatinib and the PI3Kα inhibitor BYL719. Conclusions: Our in vitro studies suggested that activation of EGFR signaling and/or genetic alteration of downstream effectors like PIK3CA were alternative resistance mechanisms used by capmatinib-resistant NSCLC cell lines. In addition, combined treatments with MET, EGFR, and PI3Kα inhibitors may be an effective therapeutic strategy in MET-TKI-resistant NSCLC patients.