The cure rate of
osteosarcoma has not improved in the past 30 years. The new treatments and drugs is urgently needed, especially for metastatic
osteosarcoma. Anti-angiogenesis
therapy and
immunotherapy has got promising anti-
tumor effects in various
tumors. It is hypothesised that combining checkpoint inhibitor
immunotherapies with antiangiogenic treatment may have a synergistic effect and enhance the efficacy of both treatments. However, its underlying mechanism remain largely uninvestigated. To investigate the clinical significance of
vascular endothelial growth factor receptor-2 (VEGFR2) and programmed death ligand-1 (PD-L1) in
osteosarcoma, we analyzes their expression levels in 93
osteosarcoma specimens by immunohistochemistry. Meanwhile, we analyzes their correlation with the metastatic behavior and overall survival (OS). We also investigate the effects of
Apatinib on migration and invasion of
osteosarcoma cells and its underlying mechanism in vitro and in vivo. In our study, the positive rates of the VEGFR2 and PD-L1 expression are 64.5% (60/93) and 35.5% (33/93), respectively. A significant correlation is detected between VEGFR2 and PD-L1 expression (P = 0.009). Receiver-operating characteristic (ROC) curves analysis indicates the predictive value of the two markers in
tumor metastasis, and both PD-L1 and VEGFR2 are negatively correlated with OS. Transwell assays reveals that VEGFR2 inhibition attenuates migration and invasion of
osteosarcoma cells. Mechanistically, we demonstrate that
Apatinib attenuates migration and invasion by suppressing epithelial-mesenchymal transition (EMT) and inactivating STAT3. Additionally,
Apatinib reduces PD-L1 expression in
osteosarcoma cells.
Apatinib markedly weakens pulmonary metastatic potential of
osteosarcoma in vivo. In conclusion, our study reveals a pro-metastatic functional mechanism for VEGFR2 in
osteosarcoma. Furthermore, we demonstrate that
Apatinib exerts anti-
tumor effect not only through antiangiogenic effect, but also via suppressing immune escape, which may represent a potential therapeutic target for metastatic
osteosarcoma.