Spatiotemporal-Controlled NIR-II Immune Agonist Sensitizes Cancer Immunotherapy

The integration of nanomedicine and immunotherapy has presented a promising opportunity for the treatment of cancer and diverse diseases. However, achieving spatiotemporal controllable immunotherapy with excellent efficacy and safety performances remains a significant challenge. This study develops a biodegradable near-infrared II (NIR-II) photothermal response polymer nanoparticle (PTEQ) system. This platform exhibits intrinsic immunostimulatory properties while concurrently delivering siRNA for Programmed Death-Ligand 1 (siPD-L1), leveraging enhanced immune responses and immune checkpoint blockade for safe and effective cancer therapy. In the CT26 tumor-bearing mouse model, PTEQ, as an immune stimulant, significantly boosts the infiltration of CD4+ and CD8+ T cells within the tumor microenvironment (TME). The PTEQ/siPD-L1+laser group not only initiates NIR-II photothermal therapy but also promotes the activation and infiltration of T cells, M1 macrophage polarization, and maturation of dendritic cells in the TME, resulting in the complete elimination of tumors in 7/10 cases, achieving a 100% survival rate. In another in vivo vaccine experiment, all tumors on the right side are completely eliminated in the PTEQ/siPD-L1+laser group, reaching a 100% tumor eradication rate. These findings underscore the potential of this strategy to overcome the current immunotherapeutic limitations and achieve immune therapy normalization.

Multifunctional Photothermal Hydrogel in the Second Near-Infrared Window for Localized Tumor Therapy

A copper selenide-embedded gellan gum hydrogel (Cu2-xSe@GG) is designed as an "all-in-one" antitumor agent. The obtained nanocomposite hydrogel exhibits strong near-infrared light absorption and high photothermal conversion efficiency in both the NIR-I and NIR-II biowindows. The photothermal conversion efficiency achieves 58.8% under the irradiation of 0.75 W/cm2 with a 1064 nm laser. Furthermore, the nanocomposite hydrogel has catalase- and peroxidase-mimicking activities, which could alter the tumor microenvironment by reducing hypoxia and/or increasing the production of reactive oxygen species. Moreover, the multifunctional Cu2-xSe@GG nanocomposite hydrogel can also be used as an immune agonist resiquimod (R848) carrier to promote immune regulation and enhance the therapeutic effect. The single-syringe R848/Cu2-xSe@GG treatment achieves synergetic photothermal immunotherapy, showing 97.4% of tumor regression rate from an initial large tumor of 300 mm3.

Bio-Inorganic Hybrid Nongenetically Modified Viruses as an Immune Agonist for Systemic Elimination of Cancer Cells

Microbial-based cancer therapy is nowadays considered as an interesting approach, especially with viruses which are attracting more attention owing to their simple structure and nanoscale. However, because of the need for cumbersome genetic modification and poor biosafety, its application is seriously limited. Here, nonpathogenic natural Sendai viruses (SEVs) are used as an alternative immune agonist after being mineralized by calcium ions. Both in vitro and in vivo studies indicated that virus-inorganic hybrids can effectively excite antigen-presenting cells (APCs). Then, the tumor antigens were released in large amounts by photothermal damage. Meanwhile, these released antigens were presented to lymph nodes to mature antitumor T lymphocytes via the peritumoral APCs previously recruited by the SEV. Our results demonstrated that even after administration at one point, the nanohybrids could still effectively stimulate systemic antitumor immune response to suppress the potential cancer metastatic spread. The bio-inorganic hybrid nongenetically modified virus-inorganic nanocomposites might serve as an alternative strategy for synergistic immune therapy.