Codelivery of Anti-PD-1 Antibody and Paclitaxel with Matrix Metalloproteinase and pH Dual-Sensitive Micelles for Enhanced Tumor Chemoimmunotherapy.

Immune checkpoint blockade (ICB) is demonstrating great potential in cancer immunotherapy nowadays. Yet, the low response rate to ICB remains an urgent challenge for tumor immunotherapy. A pH and matrix metalloproteinase dual-sensitive micellar nanocarrier showing spatio-temporally controlled release of anti-PD-1 antibody (aPD-1) and paclitaxel (PTX) in solid tumors is prepared to realize synergistic cancer chemoimmunotherapy. Antitumor immunity can be activated by PTX-induced immunogenic cell death (ICD), while aPD-1 blocks the PD-1/PD-L1 axis to suppress the immune escape due to PTX-induced PD-L1 up-regulation, thus resulting in a synergistic antitumor chemoimmunotherapy. Through decoration with a sheddable polyethylene glycol (PEG) shell, the nanodrug may better accumulate in tumors to boost the synergistic antitumor treatment in a mouse melanoma model. The present study demonstrates a potent antitumor chemoimmunotherapy utilizing tumor microenvironment-sensitive micelles bearing a sheddable PEG layer to mediate site-specific sequential release of aPD-1 and PTX.