Cytotoxicity of NK92-CD16 cells on NSCLC cell line resistant to TKI

Abstract

Purpose: The use of tyrosine kinase inhibitor (TKIs) improved outcome of non-small cell lung cancer (NSCLC) patients harboring targetable driver mutation. However, the most patients eventually showed disease progression due to the acquired resistance to TKIs by various mechanisms including gatekeeper mutation and alternative pathway activation. As immunotherapy can be considered for these patients to override drug resistance, I investigated the efficacy of NK92-CD16 cells (CD16-transduced NK-92 cell line) to TKI-resistant NSCLC cells. Methods: TKI-resistant NSCLC cells (H3122CR1, H3122LR1, H3122CR1LR1, EBC-CR1, EBC-CR2, PC-9GR and PC-9ER) were established from NCI-H3122 (EML4-ALK fusion), EBC-1 (MET amplification), and PC-9 (EGFR exon 19 deletion) after continuous exposure to crizotinib, ceritinib, capmatinib, gefitinib, and erlotinib. NK cytotoxicity and antibody-dependent cell-mediated cytotoxicity (ADCC) using anti-EGFR monoclonal antibody (mAb) cetuximab were measured using off-the-shelf NK92-CD16 as effectors and detected by the 51Chromium-release assay. Expression of the ligands for NK cell receptors and total EGFR were analyzed by flow cytometry. Results: Most of TKI-resistant NSCLC cell lines were more susceptible to NK92-CD16 cell compared with their parental cell lines. The expression of ICAM-1, which is a ligand for LFA-1 in NK cells, is higher in TKI-resistant NSCLC cells than in parental cells and is expected to be correlated with NK92-CD16 cytotoxicity. When ICAM1-CD11a interaction was blocked during a cytotoxic assay, the cytotoxicity was decreased. Cetuximab-mediated ADCC was higher in resistant cells due to the increased expression level of total EGFR in resistant cells. Conclusions: TKI-resistant NSCLC cells are more sensitive to NK92-CD16 cell-mediated cytotoxicity that is partially dependent on up-regulation of ICAM-1 via an immunological synapse. In addition, cetuximab, an EGFR-targeting mAb, significantly increases NK cell cytotoxicity in TKI-resistant NSCLC cells. Taken together, NK-cell based immunotherapy with cetuximab might be feasible to treat NSCLC patients with acquired resistance to TKIs.