Development of a prognostic index of colon adenocarcinoma based on immunogenomic landscape analysis

Background: Colon adenocarcinoma (COAD) is one of the most commonly diagnosed cancers, and it is closely related to the immune microenvironment. Considering that immunotherapy is not effective for all COAD patients, it is necessary to identify the effective population before administering treatment. In this study, we established an independent prognostic index based on immune-related genes (IRGs), in order to evaluate the clinical outcome of COAD. Methods: The gene expression profiles and IRGs taken from The Cancer Genome Atlas (TCGA) and Immunology Database and Analysis Portal (ImmPort), respectively, were integrated in order to identify the differentially expressed IRGs. Functional enrichment analysis was conducted and the prognostic value of survival-related IRGs was determined. Based on Cox regression analysis, the IRG-based prognostic index (IRGPI) was established, and the model was evaluated and applied. Results: A total of 51 differentially expressed survival-related IRGs were identified. The most significant signaling pathway was "cytokine-cytokine receptor interaction". The index established herein was based on 12 survival-related IRGs, and it was highly accurate in monitoring prognosis. Moreover, the IRGPI was significantly correlated with multiple clinicopathologic factors, as well as with the infiltration of immune cells. Conclusions: An independent IRGPI was established in order to assess the immune status and tumor prognosis in COAD patients. This index can serve as a robust biomarker in clinical prognosis applications, including cancer immunotherapy.