IFN-γ: a beneficial immune marker in triple-negative breast cancer

Cancer immunotherapy has shown promising results in triple-negative breast cancer (TNBC), however, only a small proportion of patients benefit from the immune checkpoint inhibitors (ICI). To explore robust biomarkers to predict the prognosis of TNBC patients is in great need. In this study, we first established an immune risk scoring signature with the Cancer Genome Atlas (TCGA) database. The GO and KEGG enrichment were used for cluster analysis. The KM curve was performed for prognosis. The differentially expressed immune genes were obtained for univariate and multivariate Cox and Lasso regression analysis, and 18 independent immune genes associated with prognosis were obtained to establish an immune risk score signature (IRSS). The Kaplan-Meier results showed that the prognosis of the high-risk group was significantly favorable than that of the low-risk group (P < 0.001; HR = 3.06, 95% CI = 2.16-4.32). The 18 targeted immune genes were enriched in JAK-STAT signaling pathway and IFNG was the most focus gene in TNBC compared with Luminal A/B and HER2 subtypes. Furthermore, TNBC patients with high level of both IFNG and checkpoints (CD274, PD-1, CTLA-4 and TIGHT) would have longer survival and IFNG was positively relevant to various checkpoints, especially PD-1/PD-L1. Taken together, our results indicate that dispite of the complicated effects of IFNG in immune microenvironment, IFNG is associated with better prognosis in TNBC and may act as a biomarker guiding the ICI therapy.