EWSR1 and Ewing sarcoma: Vaccination trials of fusion gene-derived peptides have been reported with BCR-ABL in 12 patients with chronic myelogenous leukemia[16], EWS-FLI1 in 12 patients with Ewing's sarcoma[17], and PAX3-FKHR in four patients with alveolar rhabdomyosarcoma[17].