Abstract 3700: Prognostic value of the expression of NKG2D and CD96 in early stage non-small cell lung cancer (NSCLC)

Abstract

Abstract Background: Immune checkpoint inhibitors showed impressive activity in advanced NSCLC and are expected to be effective in postoperative treatment of early disease. New therapies aimed at T and NK cell activation are in development to expand treatments options. It is conceivable that markers of ‘inflamed’, ‘immune system ignorant’ and ‘immune system excluding’ tumor phenotypes may be predictive for specific immune-targeting therapies. Aim: We assessed prognostic value of expression of CD8(+) T and NK cell markers: CD96 and NKG2D in early stage NSCLC. In addition, we analyzed expression of 11 transcripts of APOBEC genes with hypothesis that APOBEC induced mutation burden may affect tumor immunogenicity or host adaptive immunity responsiveness. Methods: mRNA levels were measured by RT-PCR in frozen tumor tissue from 65 NSCLC stage I-IIIA patients who underwent pulmonary resection (75% lung adenocarcinoma, 33% never-smokers, 44% with subsequent dissemination), and in 11 NSCLC cell-lines. The relative gene expression (vs. 5 normalization genes) was compared between groups that did and did not disseminate, and in relation to clinico-pathological features. Results: After Bonferroni correction for multiple testing, NKG2D and CD96 mRNA expression was significantly lower in tumors with subsequent dissemination (p.adj.=0.045). Out of 11 APOBEC genes, expression of AICDA, APOBEC3A and APOBEC3G was lower in tumors with subsequent dissemination (p.unadj.=0.025). The NSCLC lines did not express NKG2D, CD96, AICDA or APOBEC3A. The Spearman corr. coeff. between the expression of NKG2D, CD96 and APOBEC3G were ≥0.8. AICDA expression was correlated with CD96, NKG2D and APOBEC3G with Spearman corr. coeff. in the range of 0.5-0.62. Expression of CD96 and NKG2D was significantly lower in tumors with vs. without subsequent brain metastasis (p.unadj.=0.048). The negative prognostic impact of low NKG2D and CD96 expression was independent from patient smoking status (FC <1, irrespective of smoking status). In the subset of never-smokers, the fold difference of NKG2D expression between tumors with vs. without subsequent dissemination was particularly pronounced (HR=0.37; p.unadj.=0.023). In multivariate Cox analysis including stage, CD96 and NKG2D expression was significantly correlated with distant metastasis free survival (p=0.028). The expression of CD96, NKG2D and APOBEC genes was not related to gender or NSCLC histological type. IHC co-localization and mRNA expression experiments at the background of other more established markers are planned. Conclusions: Low expression of CD96 and NKG2D in early stage NSCLC may be predictive for high propensity to dissemination, including metastasis to the brain. The expression of APOBEC transcripts does not seem to correlate with metastatic potential. Citation Format: Marcin Skrzypski, Michał Marczyk, Amelia Szymanowska, Anna Kowalczyk, Agnieszka Maciejewska, Ryszard Pawlowski, Wojciech Biernat, Joanna Polańska, Jacek Jassem. Prognostic value of the expression of NKG2D and CD96 in early stage non-small cell lung cancer (NSCLC) [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 3700. doi:10.1158/1538-7445.AM2017-3700