Because evidence is growing towards the conception that the targeting of multiple RTKs is a more effective approach than targeting of a single RTK, and AXL has been implicated in resistance against IGF-1R-targeted therapy, co-targeting of AXL and IGF-1R could also be an effective treatment strategy for ES, which we are currently investigating [4, 18]. This evidence concerns the gene IGF1R and Ewing sarcoma.