Checkpoint blockade
immunotherapy has shown great potential in clinical
cancer therapy, but the body's systemic immune must be fully activated and generates a positive
tumor-specific immune cell response. In this work, we demonstrate the design of the immune-adjuvant nanodrug carriers on the basis of poly(
ethylene glycol)- block-
poly(lactic- co-glycolic acid) copolymer-encapsulated Fe3O4 superparticles (SPs), in which
imiquimod (
R837), a kind of
Toll-like receptor 7 agonist, is loaded. The nanodrug carriers are defined as Fe3O4-R837 SPs. The multitasking Fe3O4-R837 SPs can destroy the 4T1
breast tumor by
photothermal therapy (PTT) under near-infrared
laser irradiation to generate the
tumor-associated
antigens because of the high efficiency of
tumor magnetic attraction ability and photothermal effect. The PTT also triggers the release of
R837 as the adjuvant to trigger a strong antitumor immune response. By further combining with the checkpoint blockade adjusted by
programmed death ligand 1 (PD-L1) antibody, the Fe3O4-R837 SP-involved PTT cannot only eliminate the primary
tumors but also prevent
tumor metastasis to lungs/liver. Meanwhile, this synergistic
therapy also shows abscopal effects by completely inhibiting the growth of untreated distant
tumors through effectively triggering the
tumors infiltrated by CD45+ leukocytes. Such findings suggest that Fe3O4-R837 SP-involved PTT can significantly potentiate the systemic therapeutic efficiency of PD-L1 checkpoint blockade
therapy by activating both innate and adaptive immune systems in the body.