Investigation of immune microenvironment in EGFR mutant NSCLC.

Abstract

e20517 Background: Immune checkpoint inhibitor therapy has made great achievements in NSCLC, but patients with EGFR mutations have poor efficacy with immunotherapy. Previous studies have explored the expression of PD-L1, neo-antigen, co-mutation and regulatory pathways in EGFR mutate NSCLC. This work compared the immune microenvironment of EGFR mutant and wild-type NSCLC. Methods: Patients: NSCLC. Using multi-color immunohistochemistry (multi-IHC) to evaluate the expression of 2 indicators in tumors and tumor stroma, namely CD8+ T cell and macrophage. Shapiro-Wilk was used for normality test, and t-test or Mann-Whitney U test was used according to the results. Two-sided P < 0.05 was considered a significant difference. Results: The study included 119 NSCLC patients, including 59 women (49.6%) and 60 men (50.4%), with a median age of 57. There were 68 patients (57.1%) with EGFR mutations, 19 patients (16%) with KRAS mutations, and 58 patients (48.7%) with TP53 mutations. multi-IHC results showed that, EGFR mutation Vs EGFR wild type samples, (1) the number and proportion of CD8+ T cells in tumor were not statistically different. The median number of CD8+ T cells in tumor stroma was 231.5 vs 359, p = 0.05 and the proportion of CD8+ T cells was 3.92% vs 5.64%, p = 0.02; (2) The median number of macrophage in tumors was 1522 vs 110, p < 0.01, and the proportion of macrophage cells was 24.93% Vs 1.38%, p < 0.01. The median value of macrophages in tumor stroma was 617.5 Vs 208, p < 0.01, and the proportion of macrophages cells was 10.88% vs 3.03%, p < 0.01. Conclusions: Compared with EGFR wild-type patients, EGFR mutation patients have a lower proportion of CD8+ T cells and a higher proportion of macrophages in the immune microenvironment.