Abstract 3698: Associations of the immune microenvironment with PD-L1 copy number alterations and PD-L1 expression in resected non-small cell lung cancer
Authors: Yoshimura Katsuhiro , Inoue Yusuke , Kahyo Tomoaki , Kawase Akikazu , Tanahashi Masayuki , Ogawa Hiroshi , Inui Naoki , Funai Kazuhito , Shinmura Kazuya , Niwa Hiroshi , Suda Takafumi , Sugimura Haruhiko 
Published: July 2017

Background: The relationships between tumor PD-L1 expression and the tumor immune microenvironment (TIM) have gained attention in a variety of cancers including non-small cell lung cancer (NSCLC). However, the relevance of TIM according to the tumor PD-L1 copy number alterations (CNAs) whose significance have been shown in several malignancies remains to be uncovered.

Methods: We evaluated PD-1+, CD8+, and Foxp3+ lymphocytes in tumor nest and surrounding stroma separately using microarrayed 636 resected NSCLC. Their associations with PD-L1 CNAs and PD-L1 expression were analyzed. Tumor-infiltrating lymphocytes (TILs) were counted under high-power fields (×200). PD-L1 CNAs were assessed with fluorescent in situ hybridization, and were classified into three categories (amplification, polysomy, and disomy). PD-L1 expression was evaluated using immunohistochemistry (clone E1L3N), and positivity of ≥5% was used as the cut-off.

Results: In the entire cohort, the median age was 68 years (23-88 years). The cohort comprised 444 (68.0%) men and 197 (30.2%) never-smokers. The median follow-up duration was 3.6 years. The numbers of TILs in stroma were much greater than those in tumor nest. Smoking history and squamous histology were significantly associated with immune cell infiltration in both stroma and tumor nest, except for CD8+ TILs in stroma. There were 20 tumors with PD-L1 amplification (1.7%) and 84 tumors with polysomy (13.2%). PD-L1 expression was positive in 201 tumors (30.8%). In tumor nest, the numbers of individual TILs significantly increased according to the increase of PD-L1 copy number (Kruskal-Wallis, p &lt; 0.001 for PD-1+, p &lt; 0.001 for CD8+, and p = 0.0087 for Foxp3+). In stroma, only PD1+ TILs were significantly associated with PD-L1 CNAs (p = 0.0032), and CD8+ TILs tended to correlate with PD-L1 CNAs (p = 0.079). The numbers of CD8+, PD-1+, and FOXP3+ TILs were significantly greater in PD-L1-positive tumors than in PD-L1-negative tumors, in both tumor nest and stroma (p &lt; 0.001). Neither kind of TILs, PD-L1 expression, nor PD-L1 CNAs alone was independent prognostic factor for overall survival in a multivariate analysis with Cox hazards models. However, when the PD-L1 copy numbers were combined with Foxp3+ TILs, cases with tumor high PD-L1 copy numbers (≥5 copies per nucleus) and high Foxp3+ TILs had independently worse prognoses in both tumor nest and stroma infiltration (hazard ratio (HR), 4.38; 95% confidence interval, 2.26-8.49, for tumor nest model. HR, 1.96; 95% CI, 1.04-3.68, for stroma model).

Conclusion: CD8+, Foxp3+, and PD-L1+ lymphocytes in tumor nest were significantly associated with PD-L1 CNAs and PD-L1 expression. Cases with both increased PD-L1 copy numbers and Foxp3+ TILs have independently worse survival outcomes. Additional data of other TIL subgroups related to PD-L1 CNAs and expression will be discussed.

Citation Format: Katsuhiro Yoshimura, Yusuke Inoue, Tomoaki Kahyo, Akikazu Kawase, Masayuki Tanahashi, Hiroshi Ogawa, Naoki Inui, Kazuhito Funai, Kazuya Shinmura, Hiroshi Niwa, Takafumi Suda, Haruhiko Sugimura. Associations of the immune microenvironment with PD-L1 copy number alterations and PD-L1 expression in resected non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3698. doi:10.1158/1538-7445.AM2017-3698