Metal-based nanocomposites for immunotherapy of osteosarcoma

Emerging nanotechnologies demonstrate unparalleled benefits in expediting cancer treatment. Despite the widespread use of nanocomposites in tumor therapy, particularly in the treatment of osteosarcoma, there is a lack of review articles specifically focusing on their application in osteosarcoma immunotherapy. Nanocomposites have demonstrated exceptional performance in improving the effectiveness of osteosarcoma treatments, with multiple metal ions playing a pivotal role in modulating innate immune stimulation and overcoming acquired immune tolerance. The rational design of functional materials can efficiently induce immunogenic cell death in tumors or directly activate antigen-presenting cells, thereby initiating specific anti-tumor immune responses. This comprehensive review focuses on the most recent progress of the immune microenvironment in osteosarcoma, followed by an introduction to the characteristics of various metal ions (iron-based, bismuth-based, copper-based, and other metal-based nanocomposites) in osteosarcoma immunotherapy, as well as their forms and mechanisms of action in anti-tumor immune regulation: serving as an efficient cancer vaccine or nanodrugs to induce a strong tumor-specific immune response; acting as a biocompatible nanocarrier to provide immunotherapeutic agents for tumor immunotherapy. Finally, the main challenges and possible development directions in this field are highlighted, providing reference and guidance for the subsequent research on metal-based nanoparticles in the treatment of malignant bone tumors.