In addition, patients with the pulmonary metastasis of osteosarcoma were shown to have a relatively higher level of exosomal PD-L1 than patients without metastasis, and the AUC value of the ROC curve was 0.823 for exosomal PD-L1, which indicated the pulmonary metastasis progression for OS patients [30]. This evidence concerns the gene CD274 and osteosarcoma.