Extending the immune phenotypes of lung cancer: Oasis in the desert

Introduction: Tumor infiltrating immune cells are key elements of the tumor microenvironment and mediate the anti-tumor effects of immunotherapy. The aim of the study was to characterize patterns of immune cell infiltration in non-small cell lung cancer (NSCLC) in relation to tumor mutations and clinicopathological parameters. Methods: Lymphocytes (CD4+, CD8+, CD20+, FOXP3+, CD45RO+), macrophages (CD163+), plasma cells (CD138+), NK cells (NKp46+) and PD-L1+ were annotated on a tissue microarray including 357 operated NSCLC cases. Somatic mutations and tumor mutational burden were analyzed by targeted sequencing for 82 genes, and transcriptomic immune patterns were established in 197 patients based on RNAseq data. Results: We identified somatic mutations (TP53, NF1, KEAP1, CSMD3, LRP1B) that correlated with specific immune cell infiltrates. Hierarchical clustering revealed four immune classes: with (1) high immune cell infiltration (“inflamed”), (2) low immune cell infiltration (“desert”), (3) a mixed phenotype, and (4) a new phenotype with an overall muted inflammatory cell pattern but with an imprint of NK and plasma cells. This latter class exhibited low expression of immune response-related genes (e.g. CXCL9, GZMB, INFG, TGFB1), but was linked to better survival and therefore designated “oasis”. Otherwise, the four immune classes were not related to the presence of specific mutations (EGFR, KRAS, TP53) or histologic subtypes. Conclusion: We present a compartment-specific immune cell analysis in the context of the molecular and clinical background of NSCLC and identified the novel immune class “oasis”. The immune classification helps to better define the immunogenic potency of NSCLC in the era of immunotherapy.