Background/aim Ewing sarcomas most commonly arise in the bones, but can also manifest as extraskeletal tumours in soft tissues. Metastases from extraskeletal Ewing sarcomas occur in more diverse anatomical sites than skeletal tumours, and have poorer survival rates. Few animal models replicate the extraskeletal form of Ewing sarcoma, and those that have been developed do not reflect the widespread metastatic spread of these cancers. Materials and methods Luciferase-expressing Ewing sarcoma cells derived from a muscle tumour were intramuscularly or intravenously injected into nude mice. Results Both models achieved metastatic spread to numerous sites including the lungs, liver, kidneys, and brain. We characterized the cellular composition of primary and metastatic tumours, observing a greater level of immune cell infiltration in metastases compared to primary intramuscular tumours. Conclusion These pre-clinical models will hopefully facilitate the evaluation of novel therapies and contribute to better understanding the disease progression of metastatic extraskeletal Ewing sarcoma.
