Construction of immune-related risk signature for renal papillary cell carcinoma

The kidney renal papillary cell carcinoma (KIRP) is a relatively rare type of kidney cancer. There has been no investigation to find a robust signature to predict the survival outcome of KIRP patients in the aspect of tumor immunology. In this study, 285 KIRP samples from The Cancer Genome Atlas (TCGA) were randomly divided into training and testing set. A total of 1534 immune-related genes from The Immunology Database and Analysis Portal (ImmPort) were used as candidates to construct the signature. Using univariate Cox analysis, we evaluated the relationship between overall survival and immune-related genes expression and found 272 immune-related genes with predicting prognostic ability. In order to construct an efficient predictive model, the Cox proportional hazards model with an elastic-net penalty was used and identified 23 groups after 1000 iterations. As a result, 15-genes model showing more stable than other gene groups was chosen to construct our immune-related risk signature. In line with our expectations, the signature can independently predict the survival outcome of KIRP patients. Patients with high-immune risk were found correlated with advanced stage. We also found that the high-immune risk patients with higher PBRM1 and SETD2 mutations, increasing chromosomal instability, together with the gene set enrichment analysis (GSEA) results showing intensive connection of our signature with immune pathways. In conclusion, our study constructs a robust 15-gene signature for predicting KIRP patients' survival outcome on the basis of tumor immune environment and may provide possible relationship between prognosis and immune-related biological function.