Also of note, Ewing sarcoma, which is known to be driven by EWSR1 fusions, has preclinical data supporting sensitivity to PARPi therapy [38], yet had a 0% HRD rate and 3.45% DDR pathway alteration rate, among the lowest of all groups; to date, clinical trials testing PARPi have resulted in mixed responses [35,39]. This evidence concerns the gene EWSR1 and Ewing sarcoma.