Pretreatment immune status correlates with progression-free survival in chemotherapy-treated metastatic colorectal cancer patients

Abstract

It remains unclear whether the immunological status of cells in peripheral blood can be used as a prognostic indicator of predicts response to treatment for patients with unresectable metastatic colorectal cancer (MCRC). We therefore investigated the relationship between the pretreatment immunological status of 40 MCRC patients 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%) correlated with significantly shorter progression-free survival compared to none or 1 (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% CI, 2.5-34.2; P < 0.001). These results provide evidence that pretreatment peripheral immune status can inform the outcome of MCRC patients treated with first-line chemotherapy.