The relationship between immune system and cancer has met a Copernican revolution. Indeed, the inflammation is recognized as a hallmark feature of tumor development. In particular, it has been observed the opposing effects of cancer-associated inflammation, ranging from positive local effects, such as T-cell mediated cytotoxicity leading to tumor inhibition, through to cancer development and progression. In the last few years, we have learned that within the tumor microenvironment a complicate network of cells communicates to form the local immune response. It is well known that the presence of tumor necrosis and inflammatory infiltrate, constituted by T regulatory cells, fewer Th1 cells, a lot of myeloid-derived suppressor cell and expansion of M2 macrophages, promotes tumor growth and progression. The field of cancer immunotherapy has experienced alternating periods of success and failure in the development of cancer therapies. The current breakthrough in cancer immunotherapy results from the identification and subsequent targeting of checkpoint mechanisms in T cells with antibodies against CTLA-4, PD-1 and PD-L1. CTLA-4 and PD-1 are co-inhibitory receptors found on the cell surface of T cells.
Keywords: Cancer, Immune responses, Microbiome, Inflammation, Lymphocytes, Macrophages.