“…Tumor survival can depend on the PD-L1/PD-1 pathway to attenuate immunogenicity and facilitate resistance to anti-apoptotic stimuli (Hirano et al, 2005;Azuma et al, 2008;Keir et al, 2008;Gato-Canas et al, 2017;Escors et al, 2018). PD-L1 is overexpressed in many tumor types to evade the immune attack and its expression generally (but not always) correlates with progression (Gato-Canas et al, 2017;Escors et al, 2018;Bocanegra et al, 2019;Kattan et al, 2019). PD-1 is expressed in T lymphocytes and interferes with their activation when bound with their ligands PD-L1, inhibiting the effector phase and thus dampening the ability of these T cells to kill cancer cells (Keir et al, 2008;Gato-Canas et al, 2017;Zuazo et al, 2019).…”