Inhibiting platelet-derived growth factor β reduces Ewing's sarcoma growth and metastasis in a novel orthotopic human xenograft model

Backgound: Despite aggressive therapy, Ewing's sarcoma (ES) patients have a poor five-year overall survival of only 20-40%. Pulmonary metastasis is the most common form of demise in these patients. The pathogenesis of pulmonary metastasis is poorly understood and few orthotopic models exist that allow study of spontaneous pulmonary metastasis in ES. Materials and Methods: We have developed a novel orthotopic xenograft model in which spontaneous pulmonary metastases develop. While the underlying biology of ES is incompletely understood, in addition to the EWS-FLI-1 mutation, it is known that platelet-derived growth factor receptor β(PDGFR-β) is highly expressed in ES. Hypothesizing that PDGFR-β expression is indicative of a specific role for this receptor protein in ES progression, the effect of PDGFR-β inhibition on ES growth and metastasis was assessed in this novel orthotopic ES model. Results: Silencing PDGFR-βreduced spontaneous growth and metastasis in ES. Conclusion: Preclinical therapeutically relevant findings such as these may ultimately lead to new treatment initiatives in ES.