For example, studies have shown that the number of infiltrating CD8+ T cells is inversely correlated with the expression of the cystine transporter system Xc- in human melanoma tissue, and the degradation of cystine and cysteine by cyst(e)inase combined with PD-L1 blockers can synergistically enhance T cell-mediated antitumor immunity and induce tumor cell ferroptosis (100, 103). The gene discussed is CD274; the disease is melanoma.