CD274 and sarcoma: However, when PD-L1 and PD-L2 expression was taken together for analysis with PD-1 expression, the expression levels of the two PD-1 ligands were significantly correlated with PD-1 expression in the sarcomas (P = 0.000) and in osteosarcoma (P = 0.002), synovial sarcoma (P = 0.017) and chondrosarcoma (P = 0.002).