Search

The tumor microenvironment includes a complex network of immune T-cell subpopulations. In this study, we systematically analyzed the balance between cytotoxic T cells and different subsets of helper T cells in human colorectal cancers and we correlated their impact on disease-free survival. A panel of immune related genes were analyzed in 125 frozen colorectal tumor specimens. Infiltrating cytotoxic T cells, Treg, Th1, and Th17 cells were also quantified in the center and the invasive margin of the tumors. By hierarchical clustering of a correlation matrix we identified functional clusters of genes associated with Th17 (RORC, IL17A), Th2 (IL4, IL5, IL13), Th1 (Tbet, IRF1, IL12Rb2, STAT4), and cytotoxicity (GNLY, GZMB, PRF1). Patients with high expression of the Th17 cluster had a poor prognosis, whereas patients with high expression of the Th1 cluster had prolonged disease-free survival. In contrast, none of the Th2 clusters were predictive of prognosis. Combined analysis of cytotoxic/Th1 and Th17 clusters improved the ability to discriminate relapse. In situ analysis of the density of IL17+ cells and CD8+ cells in tumor tissues confirmed the results. Our findings argue that functional Th1 and Th17 clusters yield opposite effects on patient survival in colorectal cancer, and they provide complementary information that may improve prognosis. Cancer Res; 71(4); 1263–71. ©2011 AACR.

A role for the immune system in controlling the progression of solid tumors has been established in several mouse models. However, the effect of immune responses and tumor escape on patient prognosis in the context of human cancer is poorly understood. Here, we investigate the cellular and molecular parameters that could describe in situ immune responses in human colorectal cancer according to clinical parameters of metastatic lymph node or distant organ invasion (META− or META+ patients). Primary tumor samples of colorectal carcinoma were analyzed by integrating large-scale phenotypic (flow cytometry, 39 patients) and gene expression (real time reverse transcription-PCR, 103 patients) data sets related to immune and protumoral processes. In META− colorectal cancer primary tumors with high densities of T cells, we observed significant positive correlations between markers of innate immune cells [tumor-associated macrophages, dendritic cells, natural killer (NK) cells, and NKT cells] and markers of early-activated T cells. Significant correlations were also observed between markers of cytotoxic and effector memory T-cell subpopulations. These correlation profiles were absent in tumors with low T-cell infiltrates and were altered in META+ tumors with high T-cell infiltrates. We show that the coexpression of genes mediating cytotoxicity (GNLY) and Th1 adaptive immune responses (IRF1) accurately predicted patient survival independently of the metastatic status. High intratumoral mRNA expression of the proangiogenic mediator vascular endothelial growth factor was associated with significantly reduced survival rates in patients expressing high mRNA levels of GNLY. Investigation of the colorectal cancer primary tumor microenvironment allowed us to uncover the association of favorable outcomes with efficient coordination of the intratumoral immune response. [Cancer Res 2009;69(6):2685–93]