Immune checkpoint inhibitors, including anti-cytotoxic T-lymphocyte antigen-4 (CTLA-4) and anti-programmed cell-death (PD-1), require recruitment of immune cells from the tumour microenvironment and have been shown to prevent tumour growth in various pre-clinical cancer models, including RMS and other sarcomas [33–35]. Here, CTLA4 is linked to sarcoma.