<qa>  What is the main goal of CXCL10?Boosting of tumor cell killing by cytotoxic lymphocytes may be a promising means to enhance anti-tumor immunity. Prior studies demonstrated that tumor infiltration by cytotoxic lymphocytes correlates with control of tumor growth and is associated with an improved prognosis in cancer patients. Trafficking of activated lymphocytes is a tightly regulated mechanism and the specific nature of the chemokine milieu is a crucial determinant for permitting T cell entry into the tumor microenvironment. CXCL10 is an interferon-inducible chemokine particularly important for the recruitment of activated T, and it has been shown to enhance anti-tumor responses through its action on cytotoxic T cells e.g., glioblastoma, colorectal adenocarcinoma and lung carcinoma. Additionally, roles for CXCL10 as an anti-tumor effector include its ability to chemo-attract NK cells into sites of inflammation, and its ability to inhibit development of new vasculature and induce the regression of newly formed vessels. Adding a layer of complexity, the function of CXCL10 can be regulated by dipeptidylpeptidase IV DPPIV, leading to the formation of a dominant negative, antagonist form of the chemokine. This was initially demonstrated in vitro, and recent work has provided convincing in vivo evidence that antagonist forms of CXCL10 regulate lymphocyte trafficking. The main goal of this protocol is to evaluate the tolerance of sitagliptin treatment in HCC patients, and secondary DPPIV inhibitors as a strategy for protecting CXCL10 chemokine agonist activity as a means to enhance tumor regression. 