The molecule BSJ-01-175 is a novel potent CDK12/13 covalent inhibitor, showing high capacity in reducing RNAPII S2 phosphorylation, expression of BRCA1 and BRCA2 genes, and tumour growth of patient-derived xenograft of TC71 Ewing sarcoma cells [112]. This evidence concerns the gene BRCA1 and Ewing sarcoma.