PDCD1LG2 and osteosarcoma: Unlike PD-L1 and PD-1, the PD-L2-positive group had a longer OS time than the PD-L2-negative group, although the P value did not achieve statistical significance (P = 0.166), which meant that PD-L2 expression had a positive correlation trend with OS in osteosarcoma (Fig. 2b).