Ewing sarcoma has a poor prognosis, in part due to the small number of active natural killer (NK) cells and lack of specific tumor targeting. Interleukin 1 receptor accessory protein (IL1RAP) has been reported to be highly expressed in Ewing sarcoma cells but minimally expressed in normal tissues. Researchers have designed an NK cell-based CAR approach targeting ILRAP1 for the treatment of Ewing sarcoma.