1559P Chemotherapy related changes of peripheral blood lymphocytes in advanced and metastatic PDAC

Abstract

Immunotherapeutic approaches pointed out promising results in different solid tumors but remain worthless in PDAC. Immune system and TME of pts suffering from PDAC are explored widely. We conduct one institution clinical trial to evaluate impact of different treatment modalities on T lymphocyte and other cells in the peripheral blood as possible predictive and prognostic biomarkers for PDAC patients. Cohort of 77 pts with inoperable locally advanced or metastatic PDAC was evaluated in this analysis. Blood samples were collected for analysis of T cell subsets, including CD19, CD3+ CD56+, CD8+ CD57+, CD3+ CD57+, CD3, CD3+ CD4+, CD3+ CD8+, CD3+ CD4- CD8-, CD3- CD56+ CD16+, CD3- CD56+ CD16-, CD4+ CD25+ CD127+/-, CD4+ FOXP3+, CD8+ CD25+ CD127+/-, CD8+ FOXP3+ T cells by flow cytometry at initial diagnosis before chemotherapy and after two months. Results were estimated according to the age, sex, disease volume (locally advanced or metastatic, differentiation rate, regimen received (FOLFIRINOX or gemcitabine), CA 19-9 values. Student t, Mann-Whitney U and Wilcoxon Singed Rank tests were used for statistical analysis. After evaluating parameters at first visit statistically significant difference was seen in T helper subpopulation CD3+ CD4+, comparing <65 years age group and >65 years old group. The same tendency is seen comparing good/ moderately differentiated and poor diferentiated groups. Metastatic pts. tend to have lower CD3+ CD4- CD8- and CD3- CD56+ CD16- subpopulation rates before treatment. There were no significant difference of meassured parameters between groups concerning CA 19-9 elevation and sex, Initial parameters between FOLFIRINOX and gemcitabine gruops did not differ either. After 2 months on chemotherapy T lymphocytes CD3+ CD56+, NK cells CD3- CD56+ CD16+ and CD3- CD56+ CD16- as well as Treg CD4+ FOXP3+ revealed some changes. Those changes differ according to disease volume and differentiation rate. Gemcitabine showes greater impact on CD3- CD56+ CD16- fall after 2 months of chemotherapy then FOLFIRINOX. T cells subpopulations in advanced and metastatic PDAC pts vary during treatment and may be considered as potential biomarkers for evaluating pts‘ status and response to therapy.