For example, recent studies revealed that patients with relapsed Ewing sarcoma actually have circulating effector CD8+ T cells but they fail to infiltrate tumors, leading the authors to speculate that introduction of CXCL10-elevating agents into metastatic lesions might be an effective means to drive homing of the effector T cells (38). Here, CXCL10 is linked to Ewing sarcoma.