Overcoming barriers in primary bone cancer: Nanomaterial-enabled immunotherapy.

Primary bone tumors, which occur in bones or their affiliated tissues, have a low incidence rate, accounting for less than 1 % of all human malignant tumors. Seriously, the early symptoms of primary bone tumors are undetectable, and they easily metastasize, 20 % of cases are already in the advanced stage at the time of initial diagnosis. For most patients with primary bone tumors, surgery is the first choice of treatment, but its therapeutic effect is often limited. Meanwhile, primary bone tumors are generally not sensitive to other traditional tumor treatments such as radiotherapy, chemotherapy and targeted therapy, and may develop resistance to them, which often leads to a poor prognosis for patients. Crucially, immunotherapy, an important tumor treatment strategy, has been developing rapidly in recent years. It aims to improve the outcome of primary bone tumor treatment through mechanisms like remodeling immune microenvironment. Furthermore, as a new type of therapeutic carrier, nanomedicine has been widely used to improve the effects of immunotherapy, which can increase bioavailability and drug stability, reduce toxic side effects and so on, and has shown unique advantages such as high tumor targeting and high tissue permeability, making it essential for immunotherapy of primary bone tumors. In this review, we discussed the current understanding of primary bone tumors and immunotherapeutic methods, and comprehensively analyzed the application of nanomaterials in primary bone tumor immunotherapy to provide a theoretical basis and new ideas for the further development of new materials in the field of immunotherapy for primary bone tumors.