GSH-responsive camptothecin prodrug-based hybrid micellar nanoparticles enable antitumor chemo-immunotherapy by PD-L1 knockdown

The combinational chemo-immunotherapy as a novel treatment strategy has been widely studied and applied in clinic to enhance antitumor therapeutic efficacy and relieve side effects.RNA interference(RNAi)targeting PD-L1 via inhibiting novo production of PD-L1 will overcome the innate and adaptive PD-L1 expression during chemotherapy,thus enable sustained and efficient immune checkpoint blockade(ICB)to active antitumor immune response.Herein,we designed a glutathione(GSH)-responsive camptothecin(CPT)prodrug-based hybrid micellar nanoparticles(siPD-L1@HM-CPT)to achieve synergistic antitumor chemoimmunotherapy by PD-L1 knockdown.siPD-L1@HM-CPT derived from the one-step loading PD-L1 siRNA(siPD-L1)into the CPT prodrug-based hybrid micelles(HM-CPT)which were co-assembled from biodegradable polyphosphoesters-based prodrug CPT-ss-PAEEP15 and stabilizer DSPE-PEG,showed high loading efficiency,GSH-responsive drug release,and excellent stability and biosafety.siPD-L1@HM-CPT achieved simultaneously the co-delivery of CPT and siPD-L1 in vitro and in vivo,high accumulation at the tumor sites,and rapid intracellular release to promote antitumor efficacy via sensitizing CPT chemotherapy,inducing strong immunogenic cell death(ICD)and sustained ICB to improve intratumoral CD8+T cells infiltration.In addition,the antitumor immunity response limited by the differentiated immunogenicity,intrinsic PD-L1 expression,and intracellular GSH level was facilitated by efficient ICD and ICB from silencing PD-L1 and synergistic CPT chemosensitization in our experimental B16-F10 and 4T1 tumor models.Our study might offer a perspective on designing novel co-delivery nanoparticles by convenient and controllable preparation for antitumor chemo-immunotherapy.