Abstract 1192: Increased regulatory T cells induced by glycolytic metabolic change in EGFR mutant NSCLC after EGFR TKI therapy
Authors: Hong Sook-hee , Kang Nahyeon , Kim Seung joon , Kim Okrane , Kang Jin-hyoung , Sung Sook Whan 
Published: August 2019

Abstract
Background. Studies on the immune microenvironment of EGFR mutant lung cancer have been limited. We analyzed the effect of immune microenvironments on the development of EGFR-TKI resistance in EGFR-mutated lung cancer.
Methods. The EGFR mutant lung cancer cell line was co-cultured with activated PBMC for 72 hours with EGFR-TKI. Changes of cytokines/chemokines in the media, PD-1 expression of CD8+ T cells, regulatory T cells fraction and transcriptome analysis of tumor cells were analyzed. We also performed immune profile analysis of fresh tissues of 21 surgically resected NSCLC (7 EGFR mutant and 14 EGFR wild) by multicolor FACS.
Results. The Cytotoxicity of EGFR-TKI (elrotinib) in EGFR mutant HCC827 and H4006 lung cancer cell lines co-cultured with active PBMC tended to decrease. IL-6, IL-8, VEGF, TGF-B1, CXCL1, and CXCL10 were significantly increased after co-culture with activated PBMC but did not decrease after addtional EGFR-TKI treatment. IFN gamma increased after co-culture with activated PBMC but decreased after EGFR-TKI treatment. PD-L1 expression on tumor cells increased after co-culture with activated PBMC (p = 0.08 in HCC827 and p = 0.09 in H4006) but did not decrease after co-culture with activated PBMC and EGFR-TKI treatment (p = 0.36 in HCC827 and p = 0.45 in H4006). PD-L1 expression of A549 (EGFR wild type) did not change with co-culture or EGFR-TKI treatment. PD-1 expression of CD8 T cell co-cultured with HCC827 or H4006 did not change, however proportion of regulatory T cell increased after co-culture with HCC827 or H4006 (p=0.05 and p=0.08, respectively) and did not decrease during co-culture and EGFR-TKI treatment. Proportion of regulatory T cell in co-cultures with A549 or H1975 (erltinib resistant cell line) did not change during co-culture or EGFR-TKI treatment. Transcriptome analysis by RNA sequencing showed 1747 gene sets were differentially expressed in EGFR-TKI treated EGFR mutant cell line co-cultured with activated PBMC compared to EGFR-TKI treatment alone. Interferon gamma response pathway (NES 2.65, FDR q&lt;0.1) and glycolytic pathway (NES 2.15, FDR&lt;0.1) were most significantly changed. Immune profile analysis of human EGFR mutant lung cancer showed that CD4+/CD3+ T cells in EGFR mutant groups was increased compared to EGFR wild group. Proportion of FOXP3+CD25+CD4+ T reg in EGFR mutant group tended to increase compared to EGFR wild group (1.352±0.4 vs 0.74 ± 0.16%, p=0.256).
Conclusion. The regulator T cell is considered to be important in EGFR mutant NSCLC in induction of immuno suppressive microenvrionement and EGFR-TKI resistance. Study on glycolytic pathway mediated immuno suppressive microenvionment and EGFR-TKI resistance is currently ongoing
Citation Format: Sook-hee Hong, Nahyeon Kang, Seung joon Kim, Okrane Kim, Jin-hyoung Kang, Sook Whan Sung. Increased regulatory T cells induced by glycolytic metabolic change in EGFR mutant NSCLC after EGFR TKI therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1192.