Research progress of metal-CpG composite nanoadjuvants in tumor immunotherapy

The practical benefits and therapeutic potential of tumor vaccines in immunotherapy have drawn significant attention in the field of cancer treatment. Among the available vaccines, nanovaccines that utilize nanoparticles as carriers or adjuvants have demonstrated considerable effectiveness in combating cancer. Cytosine-phosphate-guanine oligodeoxynucleotide (CpG ODN), a common adjuvant in tumor nanovaccines, activates both humoral and cellular immunity by recognizing toll-like receptor 9 (TLR9), thereby aiding in the prevention and treatment of cancer. Metal nanoparticles hold great promise in tumor immunotherapy due to their adjustable size, surface functionalization, ability to regulate innate immunity, and capacity for controlled delivery of antigens or immunomodulators. Consequently, composite nanoadjuvants, formed by combining metal nanoparticles with CpG ODNs, can be customized to meet the specific performance requirements of different application scenarios, effectively overcoming the limitations of conventional immunotherapy approaches. This review provides a comprehensive analysis of the critical role of metal-CpG composite nanoadjuvants in advancing vaccine adjuvants for cancer therapy and prevention, highlighting their efficacy in preclinical settings.