Synergistic enhancement of ultrasound therapy for tumors using hypoxia-activated 6-diazo-5-oxo-L-norleucine(DON)prodrug nanoparticles

Ultrasound(US)has been applied in clinical practice for its non-invasive and high selectivity.However,it is difficult to achieve a satisfactory anti-tumor effect with US alone.Meanwhile,the use of US therapy alone can exacerbate tumor hypoxia.In this study,we prepared hypoxia-activated 6-diazo-5-oxo-L-norleucine(DON)prodrug nanoparticles(HDON-NPs)to improve US therapeutic effects.In an H22 murine liver cancer model,US therapy selectively disrupted tumor blood vessels,leading to increased tumor hypoxia and a 1.67-fold increase in the expression of nitroreductase(NTR).The combination therapy of US and HDON-NPs demonstrated a synergistic effect,resulting in a tumor suppression rate(TSR)of 90.2%±6.4%,which was 5.93-fold higher than that of US therapy alone.The combined treatment selectively blocked the glutamine metabolism of the tumor cells while simultaneously activating the T cells in the tumor microenvironment,thereby exerting a robust anti-tumor effect.

Bispecific prodrug nanoparticles circumventing multiple immune resistance mechanisms for promoting cancer immunotherapy

Cancer immunotherapy is impaired by the intrinsic and adaptive immune resistance.Herein,a bispecific prodrug nanoparticle was engineered for circumventing immune evasion of the tumor cells by targeting multiple immune resistance mechanisms.A disulfide bond-linked bispecific prodrug of NLG919 and JQ1(namely NJ) was synthesized and self-assembled into a prodrug nanoparticle,which was subsequently coated with a photosensitizer-modified and tumor acidity-activatable diblock copolymer PHP for tumor-specific delivery of NJ.Upon tumor accumulation via passive tumor targeting,the polymeric shell was detached for facilitating intracellular uptake of the bispecific prodrug.NJ was then activated inside the tumor cells for releasing JQ1 and NLG919 via glutathione-mediated cleavage of the disulfide bond.JQ1 is a bromodomain-containing protein 4 inhibitor for abolishing interferon gamma-triggered expression of programmed death ligand 1.In contrast,NLG919 suppresses indoleamine-2,3-dioxygenase 1-mediated tryptophan consumption in the tumor microenvironment,which thus restores robust antitumor immune responses.Photodynamic therapy(PDT) was performed to elicit antitumor immunogenicity by triggering immunogenic cell death of the tumor cells.The combination of PDT and the bispecific prodrug nanoparticle might represent a novel strategy for blockading multiple immune evasion pathways and improving cancer immunotherapy.