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MA15 - Immunotherapy Prediction (ID 400)
- Event: WCLC 2016
- Type: Mini Oral Session
- Track: Chemotherapy/Targeted Therapy/Immunotherapy
- Presentations: 1
MA15.07 - Molecular Determinants of Lack of Tumor Immune Infiltration in NSCLC (ID 5191)
14:20 - 15:50 | Author(s): R. Bao
Non-small cell lung cancer (NSCLC) make up the majority of all lung cancer cases and is associated with very poor prognosis. Immune checkpoint blockers have now been shown to induce unprecedented durable response in a fraction of NSCLC patients with pre-existing T cell infiltration within their tumor. However in order to improve their efficacies beyond this subset of patients, a detailed molecular characterization to identify factors associated with lack of T cell infiltration is needed. A recent analysis in metastatic melanoma identified Wnt/B-catenin pathway activation as a mechanism for lack of T cell infiltration. We pursued similar analyses of immunologic gene signatures and molecular associations in squamous cell lung cancer (SCC) and lung adenocarcinoma (LA).
We analyzed RNAseq data from two lung cancer datasets of The Cancer Genome Atlas (TCGA) (N = 499 for SCC and N = 514 for LA). Samples were categorized into non-T cell inflamed and T cell-inflamed groups using unsupervised consensus clustering based on the expression of 160 immune-related genes. Ingenuity pathway analysis was utilized to identify molecular pathways activated in non-T cell-inflamed tumors.
A similar proportion of non-T cell-inflamed tumors were identified in the two cohorts (SCC: 34%; LA: 31%). 47% of the SCC tumors were identified as T cell-inflamed, as compared to 37% in LA. A positive correlation was observed between CD8A and PD-L1, IDO1, LAG3 and TIM3 (p<0.00001). Total of 1,216 genes are significantly up-regulated in non-T cell-inflamed SCC tumors and 596 in LA with at least 1.5-fold change and FDR-adjusted p<0.05. Among these, a total of 194 genes are up-regulated in both SCC and LA, with the rest being specific for each subtype (SCC: 84%; LA: 67%). Pathway analysis suggested 35 upstream regulators were activated in SCC and 32 in LA (activation z-score≥2.0). Among these, 10 upstream regulators are activated in both datasets (ATF4, CTNNB1, KAT6A, KLF4, MYC, NFE2L2, PI3K, SCAP, SP1, SREBF2). Finally, we performed the same gene expression analysis on RNAseq data from matched normal tissues (N = 51 for SCC and N = 59 for LA) and confirmed that the T-cell inflamed gene signature is a property of the tumor rather than normal lung tissue.
Our analyses successfully identified genes and associated pathways that are enriched in NSCLC subtypes with no immune infiltration. Rational strategies to improve the efficacy of immune checkpoint blockers beyond the current subset of responders should be based on targeting these pathways.
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