CD274 and Ewing sarcoma: A retrospective study of 500 pediatric cancer patients found PD-L1 expression at varying degrees in neuroblastoma (18.9%), Ewing’s sarcoma (7.7%), osteosarcoma (6.7%), and rhabdomyosarcoma (5.6%), and in neuroblastoma high PD-L1 expression was significantly correlated with a higher risk of relapse [76].