Overexpression of LILRB2 (ILT4) is correlated with immunosuppressive immune infiltration in lung adenocarcinoma.

e20519 Background: Immune checkpoint inhibitors have revolutionized the patterns of tumor treatment with significantly improved survival. However, it’s worth noting that the objective response rate of PD-1/PD-L1 inhibitors monotherapy is just 20% in non-small cell lung cancer (NSCLC) patients, and biomarkers for the prognosis of patients receiving PD-1/PD-L1 inhibitors are urgently needed. LILRB2 (ILT4) is known as an immunosuppressive molecule and promotes the development and progression of NSCLC. However, the relationship between LILRB2 expression and immune microenvironment remains unclear in patients with lung adenocarcinoma. Methods: Expression profile and corresponding clinicopathological data of patients with lung adenocarcinoma were obtained from The Cancer Genome Atlas (TCGA) database. TIMER 2.0 was used to investigate the relationship between LILRB2 expression and immune infiltrates, including T cell subset, macrophage and so on. Cox proportional hazard model was also performed to evaluate the role LILRB2 expression and immune infiltrations in prognostic prediction of patients with lung adenocarcinoma. Results: 515 patients with lung adenocarcinoma were included in analysis from TCGA dataset. LILRB2 expression was found to have significant negative correlation with CD8+ T cell infiltration (P = 0.0012), and positive correlation with CD4+ T cell infiltration (P < 0.001). There were also significant positive correlations between LILRB2 expression and Treg (P = 0.0083), cancer associated fibroblast (P < 0.001), monocyte (P < 0.001), M2 macrophage (P < 0.001) infiltration, which was regarded as the marker of immunosuppressive microenvironment. Notably, there were also significant association between the expression of LILRB2 and PD-1 (P < 0.001) and PD-L1(P < 0.001). In terms of survival analysis, high level of Treg (HR = 0.86, P = 0.03) and M2 macrophage (HR = 0.84, P = 0.017) infiltration was associated with poor prognosis of patients with lung adenocarcinoma. However, the level of CD8+T cell (HR = 0.93, P = 0.298), CD4+ T cell (HR = 0.933, P = 0.321), and LILRB2 expression (P = 0.56) was not associated with the survival of patient with lung adenocarcinoma. Conclusions: The overexpression of LILRB2 is significantly correlated with immunosuppressive immune infiltration and microenvironment in lung adenocarcinoma and might be the potential predictive biomarkers for the PD-1/PD-L1 inhibitors.