Recently, our group reported that dual immune checkpoint blockade of anti-PD-L1 (P1) and anti-CTLA-4 (C4) antibodies combined with single delivery of 10 Gy X-ray irradiation enhanced the systemic antitumor response both at local and distant sites in murine osteosarcoma [31]. This evidence concerns the gene CTLA4 and osteosarcoma.