Clinical impact of chemotherapy to improve tumor microenvironment of pancreatic cancer.

A perioperative multimodal strategy including combination chemotherapy and radiotherapy, in addition to surgical resection, has been acknowledged to improve patient prognosis. However chemotherapy has not been actively applied as an immunomodulating modality because of concerns about various immunosuppressive effects. It has recently been shown that certain chemotherapeutic agents could modify tumor microenvironment and host immune responses through several underlying mechanisms such as immunogenic cell death, local T-cell infiltration and also the eradication of immune-suppressing regulatory cells such as regulatory T cells (Tregs) and myeloid-derived suppressor cells. With the better understanding of the cell components in the tumor microenvironment and the effect of chemotherapy to improve tumor microenvironment, it has been gradually clear that the chemotherapeutic agents is two-edged sword to have both immune promoting and suppressing effects. The cellular components of the tumor microenvironment include infiltrating T lymphocytes, dendritic cells, regulatory T cells, tumor associated macrophages, myeloid derived suppressor cells and cancer associated fibroblasts. Based on the better understanding of tumor microenvironment following chemotherapy, the treatment protocol could be modified as personalized medicine and the prognosis of pancreas cancer would be more improved utilizing multimodal chemotherapy. Here we review the recent advances of chemotherapy to improve tumor microenvironment of pancreatic cancer, introducing the unique feature of tumor microenvironment of pancreatic cancer, interaction between anti-cancer reagents and these constituting cells and future prospects.