IDO1 and neoplasm: In PdPtCu/NLG919@BSA-Ce6/TER, the IDO inhibitor NLG919 blocks the tryptophan/kynurenine immune escape axis, enhancing effector T-cell function while suppressing regulatory T-cells, thereby amplifying tumor-specific immunity induced by PdPtCu-modulated oxidative stress (Table 1) (Xie Y. et al., 2023).