Immune gene expression, survival outcome and response to PD-1/PD-L1 blockade: A TCGA pan-cancer analysis.

3033Background: Immune infiltration predicts survival in particular cancer-types. However, differences in immune profiling and associations with patient outcomes among multiple cancer-types have not been fully explored. Methods: Clinical and RNA-seq data from 9,761 tumors representing 30 cancer-types were obtained from TCGA project. The expression of 35 immune-related gene signatures tracking various cell-types was evaluated, including PD1, CTLA4, CD8A and CD4 genes. Association of each signature with overall survival (OS) was evaluated using Cox models. Correlations between each signature and the overall response rates (ORR) following anti-PD1/PDL1 monotherapy in each cancer-type (as reported in the literature) were evaluated across 16 cancer-types. Results: In the combined dataset, 15 out of 35 signatures (43%) mostly tracking cytotoxic T-cell response (e.g. CD8-T-cell, PD1 and CD8A) were highly correlated (mean coefficient [cc] = 0.69). The top 5 cancer-types with the highest percentages of samples exp...