Tumour microenvironment changes after osimertinib treatment resistance in non-small cell lung cancer.

BACKGROUND:Growing evidence suggests that acquired resistance to targeted therapy in non-small cell lung cancer patients is linked to the mutual domestication between the tumour and its surrounding microenvironment. AIM:Our study aims to explore the remodelling of tumour microenvironment after osimertinib treatment resistance. METHODS:We took RNA-seq-based tumour immune infiltration analysis using the TIMER 2.0. We carried out flow cytometry assay and real-time cell analysis to explore the interaction between tumour cells and immune cells. In addition, we analysed exosomes via miRNA-seq and label-free proteomics. RESULTS:Immune infiltration estimation showed a significant decrease in the immune score (P < 0.001), microenvironment score (P < 0.001) and CD8+ T cells (P < 0.05), but an increase in M0 macrophages (P < 0.01) at osimertinib resistance compared to pre-treatment patients. It was demonstrated that exosomes from H1975OR cells could be taken up by macrophages and drove their polarisation towards the M2 phenotype, and the polarised M2 macrophages could reduce the inhibitory effect on tumour cell proliferation. Pre-activated peripheral blood mononuclear cells exhibited a more potent killing effect on H1975OR cells. We also detected a decrease in CD4+HLA-DR- T cells and an increase in CD4+PD1+ T cells after being co-cultured with H1975OR derived exosomes or conditioned medium. Further miRNA-seq and proteomics analysis of exosomes demonstrated that mir-1258-3p and miR-17-5p might participate in this interaction. CONCLUSIONS:An immunosuppressive environment, characterised by decreased T cell infiltration and activation, whereas increased macrophage infiltration and M2 polarisation, was identified at osimertinib resistance. This interaction may be carried out by tumour-derived exosomes.