Data from Pretreatment Immune Status Correlates with Progression-Free Survival in Chemotherapy-Treated Metastatic Colorectal Cancer Patients

It remains unclear whether the immunologic status of cells in peripheral blood can be used as a prognostic indicator of response to treatment for patients with unresectable metastatic colorectal cancer (MCRC). We therefore investigated the relationship between the pretreatment immunologic status of 40 patients with MCRC who planned to receive the first-line chemotherapy and their progression-free survival. Twenty-five immune cell subsets, including monocytic myeloid-derived suppressor cells (M-MDSC) and effector memory T cells (TEM), were measured by multicolor-flow cytometry. We divided patients into high and low (above and below the median, respectively) groups based on the median value for each immune cell subset and compared progression-free survival of the two groups. Patients with high M-MDSC, low CD4+ TEM, or low CD8+ TEM quantities had significantly shorter progression-free survival (P = 0.004, 0.005, and 0.002, respectively). Patients were classified into two prognostic groups based on numbers of adverse factors; having two or three adverse factors (n = 21, 52.5%) was correlated with significantly shorter progression-free survival compared with none or one (n = 19, 47.5%; P < 0.001). The presence of two or three adverse factors was an independent poor prognostic factor for progression-free survival (HR, 9.2; 95% confidence interval, 2.5–34.2; P < 0.001). These results provide evidence that pretreatment peripheral immune status can inform the outcome of patients with MCRC treated with first-line chemotherapy. Cancer Immunol Res; 4(7); 592–9. ©2016 AACR.