Moreover, we established for the first time a strong antitumor effect of the EZH2-inhibitor tazemetostat in a PBRM1-mutated PDX, suggesting PBRM1 as a new potential theragnostic marker in chordoma and supporting further evaluation of EZH2-inhibitors in this subgroup of chordomas. This evidence concerns the gene PBRM1 and chordoma.