PDCD1 and osteosarcoma: While anti-PD-L1 or anti-PD-L2 agents have not yet been evaluated in pediatric sarcomas, in a murine model of osteosarcoma nivolumab (an anti-PD-1 monoclonal antibody) increased tumor infiltrating CD4+ and CD8+ T cells with greater cytotoxic potential (i.e., granzyme B and IFN-γ production) and less lung metastases (186).