Cancer is one of the main diseases threatening human health. Immunotherapy, in which cancer is treated by activating immune cells and inducing the body's immune response, has rapidly developed. Photothermal therapy (PTT), a new treatment method that ablates tumors by light irradiation, has attracted great attention for its good therapeutic effect and low toxic side effects. In the present study, we combined photothermal and immunotherapy to design a novel nanoparticle delivery system by loading indoleamine 2,3-dioxygenase (IDO) inhibitors and toll-like receptor (TLR) agonists into polydopamine (PDA) nanoparticles coated with polyethylene imine (PEI). This delivery system has the advantages of high homogeneity, good stability, excellent biocompatibility, and low toxicity. In vitro antitumor studies showed that the system effectively inhibited the proliferation of mouse breast carcinoma cells and induced cell apoptosis. From the in vivo studies, we found that the system inhibited the growth of mouse breast carcinoma, facilitated the maturation of antigen-presenting cells, promoted T lymphocyte differentiation, and induced the body's immune response. The present study developed a dual functional drug delivery system combining photothermal therapy and immunotherapy to efficiently improve antitumor therapy with potential clinical application.
Keywords: 1-methyl-D-tryptophan; drug delivery system; imiquimod; immunotherapy; photothermal therapy; polydopamine; tumor.