*2.1. Immune Targets in Cancer*

2.1.1. Immune Cells and Tumor Microenvironment at a Glance

It is now well-established that immune evasion is a hallmark of cancer [23]. This concept is related to cancer immunoediting, comprising three processes: elimination, equilibrium, and escape [24]. Immune cells are notably present within the TME, a complex network made up of numerous cellular (e.g., vascular, stroma cells) and non-cellular (e.g., extracellular matrix, ECM) components, other than tumor cells. These immune cells (from both innate and adaptive immunity) can either promote or prevent tumor growth. Tumor-promoting immune cells include regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs), and tumor-associated macrophages (TAMs). Conversely, tumorpreventing immune cells include CD4+ T helper cells (TH), CD8+ cytotoxic T lymphocytes (CTLs), and natural killer (NK) cells [25]. For a greater insight into the functions of the various immune cells, readers are directed to a comprehensive review conducted by Doshi and Asrani [26]. Since TME is a very immunosuppressive milieu, it seems particularly relevant to pharmacologically activate immune cells (within lymphoid organs or the TME itself) or to target immunosuppressive cells or the combination of these approaches [25]. Interestingly, these strategies can be carried out to potentially target all immune "compartments" (i.e., TME, circulation, and myeloid/lymphoid tissues) since the immunological imbalance in cancer goes beyond the primary tumor [27].
