**1.1 Biology of immune checkpoints inhibitors (ICIs)**

T-cell activation is central to the immune response [1]. However, uncontrolled T cell activation leads to T cell exhaustion and autoimmune diseases [2, 3]. Therefore, it is crucial to maintain immune homeostasis and the balance of both co-stimulatory and co-inhibitory signals. These signals are thus referred as immune checkpoints. The major co-inhibitory receptors expressed on activated T cells are programmed cell death 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). Here, we will briefly discuss their mechanisms of action.
