EWSR1 and Ewing sarcoma: PARP inhibition as an approach to the treatment of Ewing sarcoma has attracted increasing attention over the past years, after the publication by Garnett and colleagues identified the translocation EWS-FLI1 as a biomarker for PARP inhibitor sensitivity, and Brenner et al. reported that EWS-FLI1 interacts with PARP1 and influences its transcriptional activity.