Figure 6.

a) Schematic illustration of enzyme activatable prodrug vesicles (EAPVs) for PDT combined with an IDO inhibitor (NLG919). b) Confocal images analysis for revealing the penetration depth of EAPVs on CT26 multicellular spheroids. c) NLG919 release profiles after incubation with 10 mm GSH and 2.5 µg mL⁻¹ MMP‐2. d) The ratio of kynurenine to tryptophan on CT26 after different treatments, indicating NLG 919 effectively inhibited the activity of IDO. EAPVs induced ICD, leading to e) an increase in the amount of CD8⁺ T cells and f) a decrease in the population of Tregs in tumor sites. Reproduced with permission.^{[ 140 ]} Copyright 2019, American Chemical Society.