Immunomodulatory metal-based biomaterials for cancer immunotherapy

Cancer immunotherapy, as an emerging cancer treatment approach, harnesses the patient's own immune system to effectively prevent tumor recurrence or metastasis. However, its clinical application has been significantly hindered by relatively low immune response rates. In recent years, metal-based biomaterials have been extensively studied as effective immunomodulators and potential tools for enhancing anti-tumor immune responses, enabling the reversal of immune suppression without inducing toxic side effects. This review introduces the classification of bioactive metal elements and summarizes their immune regulatory mechanisms. In addition, we discuss the immunomodulatory roles of biomaterials constructed from various metals, including aluminum, manganese, gold, calcium, zinc, iron, magnesium, and copper. More importantly, a systematic overview of their applications in enhancing immunotherapy is provided. Finally, the prospects and challenges of metal-based biomaterials with immunomodulatory functions in cancer immunotherapy are outlined.