Circulating Immune Biomarkers in Peripheral Blood Correlate With Clinical Outcomes in Advanced Breast Cancer

Abstract Identification of the different elements intervening at the immunoedition process, in each body compartment, seems key to explain clinical evolution in several tumor types. In this study, a set of immune biomarkers (myeloid derived suppressor cells, regulatory T cells, and OX40+ and PD-1+ T lymphocytes counts) in peripheral blood of patients diagnosed with advanced breast cancer, were analyzed prior to and along the implementation of first line antineoplastic therapy. Subsequently, a formal comparison between groups with clinical benefit versus progression of disease and with a healthy women cohort was executed. Results reflected that patients basally showed higher levels of myeloid derived suppressor cells (35.43, IR=180.73 vs 17.53, IR=16.96 cells/μl; p=0.001) and regulatory T cells (32.05, IR=29.84 vs 22.61, IR=13.57 cells/μl; p=0.001) in comparison with healthy women. Furthermore, after therapy, an increase in the number of activated T lymphocytes (expressing OX40), and a decrease of immune inhibitory cells (MDSCs, and Tregs), and the number of inhibited (or exhausted) T lymphocytes (expressing PD-1), could be ascertained in patients with clinical benefit (p≤0.001). The opposite trend was observed in the case of disease progression. These findings suggest that some critical immune elements can be easily detected and measured in peripheral blood, which open a new opportunity for translational research, as they seem to be clearly correlated with clinical evolution, at least in ABC.