CD274 and neoplasm: At the end of the experiment, the tumor weight of the siRNA@PLGA NPs group was 83.3% lower than that of the PBS-injected group, while the tumor weight of the single-loaded PD-1 siRNA group (siPD-1@PLGA), the single-loaded PD-L1 siRNA group (siPD-L1@PLGA) and the free monoclonal antibody group (PD-1-Ab) were 16.7%, 29.2% and 14.2% lower than those of the PBS-injected group, respectively.