Finally, although BEMPEG monotherapy showed modest efficacy against the DLM8 subcutaneous osteosarcoma model, combination with anti‐CTLA‐4 or anti‐PD‐1 checkpoint inhibitor antibodies led to durable tumor growth control with long‐term survival, including complete cures in a significant fraction of treated animals. This evidence concerns the gene CTLA4 and osteosarcoma.