T_(reg), Chemokines, and Other Small Molecules! Role In Metastasis and Its Prevention Experiences in Melanoma Immunobiology

摘要

It has long been known that malignant tumors contain variable numbers of lymphocytes referred to as tumor-infiltrating lymphocytes (TIL). In melanoma, the intensity of this lymphocytic infiltrate is correlated with outcome measures, though there is some debate in the literature that such an association may only exist for certain melanomas, for example, of a certain thickness. However, early studies on melanoma TIL did not immunophenotype these cells, and recent data have revealed that the composition of the tumoral lymphocytic infiltrate is not homogenous, but rather represents varying contributions from many lymphocytic subsets. Furthermore, the function of CD8 TIL is often compromised as a result of the accumulation of immunoregulatory cells and various tumor escape mechanisms. Nevertheless, the increase in our understanding of immunobiology has facilitated the development of logical immunother-apeutic strategies to overcome such hurdles. Examples of these strategies which are currently being tested in clinical trials and which are discussed in-depth include blocking antibodies against CTLA-4 and therapies to deplete Foxp3~+ regulatory T cells (T_(reg)), which will hopefully enhance existing immunotherapeutical protocols such as tumor immunization. In addition to strategies designed to tip the balance between antitumor immunity and regulatory T-cell function, a greater understanding of the small molecules which govern the migration of immunocytes and tumor cells (chemokines) has made possible the development of strategies to selectively impede certain immunocyte populations into the tumor microenvironment, as well as to abrogate the chemokine-mediated metastasis of tumor cells. This chapter highlights some of these current developments occurring in the field of immunological cancer therapy, and illustrates how these developments resulted from a greater understanding of basic immunobiology.