Epidermal growth factor receptor tyrosine kinase inhibitor remodels tumor microenvironment by upregulating LAG-3 in advanced non-small-cell lung cancer

Abstract

Introduction: Previous clinical investigations have demonstrated that patients with non-small-cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutation have moderate responses to programmed cell death-1 and it's ligand-1 (PD-1/PD-L1) inhibitors, while some patients who failed EGFR-tyrosine kinase inhibitor (TKI) therapy could benefit from immunotherapy. As a result, we have explored alterations in the tumor immune microenvironment (TIME) before and after EGFR-TKI treatment to detect the chances and proper timing of immunotherapy among patients.

Methods: We identified 16 paired tissue samples pre- and post-EGFR-TKI treatment. Sections 4 μm thick were utilized to evaluate CD8, PD-L1, PD-1, LAG-3, and TIM-3 expressions by multiplexed fluorescent immunohistochemical staining. Five to ten representative original multispectral images of each sample were employed in the analysis.

Results: Patients with positive CD8 + T-cell infiltration accounted for 37.5 % at baseline. Positive expression of PD-L1, PD1, LAG-3, and TIM-3 cells were observed in seven (43.8 %), four (25 %), one (6.25 %) and five (31.25 %) of the patients, respectively. PD-1 expression and infiltration of CD8⁺PD-1⁺-exhausted T cells increased significantly in patients with EGFR L858R mutation compared to patients with EGFR 19DEL. Patients who acquired T790 M after TKI treatment had less infiltrations of CD8⁺PD-1⁺ T cells and CD8⁺TIM-3⁺ T cells in the TIME at baseline. Positive expression of checkpoint proteins-including PD-1, TIM-3, and LAG-3-significantly correlated with shorter progression-free survival. LAG-3 was significantly upregulated after TKI treatment (p = 0.003), while other checkpoint proteins remained stationary.

Conclusion: The present study is the first work to report LAG-3 upregulation after EGFR-TKI failure in advanced NSCLC, which proposed novel insights for rational use of LAG-3 inhibitors in advanced NSCLC patients with EGFR mutation.

Keywords: EGFR-TKI; Immune checkpoint proteins; LAG-3; NSCLC; Tumor immune microenvironment.