Abstract 4981: Comprehensive analysis of immune phenotypes identifies CD73⁺CD163^highmacrophages as a prognostic biomarker in lung adenocarcinoma

To better understand the immune profile within the tumor microenvironment (TME) and the potential immune-evasion capacity that may arise from administration of immune checkpoint inhibitors, we investigated immunological phenotypes and their correlations with genomic alterations in order to provide predictive/prognostic implications in lung adenocarcinoma (LAC).Surgical sections with corresponding peripheral blood mononuclear cells were collected from 76 patients with pathologically confirmed Ia-IIIa. The histological contents expressing immune checkpoint molecules in the tumor nest and stromal area were imaged and quantified using a multi-spectral imaging system. Distribution of tumor mutation burden (TMB) and non-synonymous somatic mutations were analyzed in whole exome sequencing (WES) data.Total 76 patients consisted of EGFR-mutant (n=37) and EGFR-wild type (n=39) tumors. As is well known, the number of tumor-infiltrating cytotoxic T cells (174.7 ± 24.4 cells/mm2) and TMB (3.8 ± 0.4) in EGFR-mutant tumors was significantly lower than those of EGFR wild type tumors (394.2 ± 82.3 cells/mm2 and 6.7 ± 1.2) (p=0.0146 and p=0.0254, respectively), elucidating EGFR mutation-mediated immune evasion. The subjects carrying EGFR wild-type were classified into two subgroups by the density of tumor-infiltrating cytotoxic T cells, defined as the high TIL (n=20) and low TIL (n=19). There was great difference of mean density of cytotoxic T cells between low TIL group (129.6 ± 16.8 cells/mm2) and high TIL group (672.8±143.5 cells/mm2). Tumor-infiltrating T cells were granzyme B-positive, suggesting most cells were tumor-specific. Interestingly, no significant difference in TMB was found between the two subgroups (7.5 ± 1.9 in low TIL group vs. 5.8±1.3 in high TIL group; p=0.4642). Tumor proportion score (TPS) of PD-L1 was remarkably higher in high TIL group than low TIL group (29.7 ± 6.5% vs. 13.9 ± 2.8%, p=0.0008, respectively), but no significant differences of tumoral CD73 and IDO between the two groups (p=0.643 and p=0.923, respectively). Even there were no significant differences in counts of tumor-infiltrating macrophages in all types of macrophage, significantly higher counts of PD-L1+ M1-type macrophages (CD68+ CD163low) in the stromal area were discovered in the high TIL group compared to those of the low TIL group (396.2 ± 93.6 vs. 139.8 ± 30.1, p=0.0114, respectively), indicating that most of macrophages resided in the stromal area. Interestingly, the low TIL group exhibited higher counts of CD73+ M2-type macrophages (CD68+ CD163high) in the stromal area than the high TIL group (644.5 ± 110.9 vs. 387.9 ± 73.2, p=0.0639, respectively). Cell count ratio (M1/M2) of macrophages was significantly higher in the high TIL group (p=0.0042), suggesting that the TME with a smaller number of TILs tends to contain more M2-type macrophages. The tumor recurrence was more frequent in the low TIL group compared to the high TIL group with no statistical significance (p=0.127). In surgically resected lung adenocarcinoma patients, the subgroup with a low density of tumor-infiltrating cytotoxic T cells had a large number of CD73+ M2-type macrophages, which may contribute to poor prognosis. Acknowledgement: This study was sponsored by Ono Pharma Co., Ltd Citation Format: Jae-Hwan Kim, Tae-Min Kim, Sung-Gu Her, Kyoung-Ho Pyo, Jeong- Oh Kim, Beung-Chul Ahn, Byoung Chul Cho, Jin Hyoung Kang. Comprehensive analysis of immune phenotypes identifies CD73+ CD163high macrophages as a prognostic biomarker in lung adenocarcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4981.