In order to reduce the immune-related adverse effects (irAEs) of systematically injected anti-PD-L1 mAb, an engineered PD-L1 trap is designed and its coding plasmid DNA is targeted delivered via lipid-protamine-DNA (LPD) nanoparticles to locally and transiently produce PD-L1 trap fusion protein in the tumor tissue. Here, CD274 is linked to neoplasm.