Evaluation of VTP-50469, a menin-MLL1 inhibitor, against Ewing sarcoma xenograft models by the pediatric preclinical testing consortium.

Background VTP-50469 is a potent inhibitor of the menin-MLL1 interaction and is implicated in signaling downstream of EWSR1-FLI1. Procedure VTP-50469 was evaluated against seven Ewing sarcoma (EwS) xenograft models and in vitro against EwS cell lines. Results VTP-50469 showed limited antitumor activity, statistically significantly slowing tumor progression in four tumor models but with no evidence of tumor regression. In vitro, the IC50 concentration was 10 nM for the mixed lineage leukemia (MLL)-rearranged leukemia cell line MV4;11, but > 3 mu M for EwS cell lines. Conclusions In contrast to its high level of activity against MLL1-rearranged leukemia xenografts, VTP-50469 shows little activity against EwS models.