Careful review of how targeted therapies have been successful in clinical trials for other human malignancies [e.g., immune checkpoint blockade in metastatic melanoma (168, 169, 172, 174, 175)] and systematic analysis of clinical trials of related families of childhood cancers [e.g., PARP inhibition in Ewing's sarcoma (138)] provide valuable insight into translating these therapies into a RMS tumor context. This evidence concerns the gene PARP1 and Ewing sarcoma.