Galectins are expressed by tumor and immune cells and have been shown to modulate the immune response in cancer through different mechanisms, such as the induction of apoptosis in activated T cells (galectin-1), the promotion of cytokine release into the immunosuppressive environment (galectin-1) or the regulation of T cell exhaustion and, in turn, the modulation of immunotherapy efficacy (galectin-9, Gal-9) [103]. This evidence concerns the gene LGALS9 and cancer.