Photothermal therapy mediated by gold nanocages composed of anti-PDL1 and galunisertib for improved synergistic immunotherapy in colorectal cancer

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths worldwide. The primary treatment for CRC is surgical resection, along with chemotherapy in more advanced or inoperable cases. There is a growing interest to complement both curative and palliative treatment with immunotherapies such as the programmed cell death-1 (PD-1) and PD-ligand 1 (PDL1) checkpoint inhibitors and transforming growth factor (TGF) β inhibitors. However, the clinical outcomes of current immunotherapeutic strategies are limited by tumor heterogeneity and drug resistance. Nanomedicine-based photothermal therapy (PTT) has shown encouraging results for solid tumor ablation. Herein, we designed and synthesized gold nanocages functionalized with primary macrophage membrane and surface anti-PDL1 antibody, and loaded with a TGFβ inhibitor, galunisertib. The GNC-Gal@CMaP nanocomposites achieved low-temperature PTT and immunogenic cell death, which subsequently enhanced the anti-tumor efficacy of anti-PDL1 antibody and galunisertib via activation of antigen-presenting cells that primed tumor-specific effector T cells. This study provides experimental proof for a combination of immunotherapy and PTT against CRC. STATEMENT OF SIGNIFICANCE: The combination of photothermal therapy (PTT) with immunotherapy can achieve an inherently synergistic anti-tumor effect. Here we integrated low-temperature PTT, PDL1 antibody and TGF-β inhibitor in hollow gold nanocage nanocomposites (GNC-Gal@CMaP) that selectively targeted colon cancer cells and accumulated in the tumor microenvironment. The GNC-Gal@CMaP nanocomposites achieved low-temperature PTT and immunogenic cell death, which subsequently enhanced the anti-tumor efficacy of anti-PDL1 antibody and galunisertib via activation of antigen-presenting cells that primed tumor-specific effector T cells. This study provides experimental proof for a combination of immunotherapy and PTT against CRC.