The aim of the present study was to evaluate the antitumor activity of drugs in phase II clinical trials for recurrent or refractory EWS. A systematic review was performed using clinical trials from four data sources: i) ClinicalTrials.gov; ii) PubMed; iii) Clinicaltrialsregister.eu; and iv) American Society of Clinical Oncology. The search terms included: '(Ewing sarcoma OR Ewing family of tumors) AND (phase II OR phase I/II)'. Overall, 465 trials were identified and 64 were included in the present study, of which, 37 had published results. The highest objective response rate came from irinotecan-based chemotherapy. Currently, the majority of targeted therapy has failed to demonstrate any activity except for regorafenib. Trials using anti-angiogenesis small molecular tyrosine kinase inhibitors (aaTKIs) are currently ongoing with promising early results. For immunotherapy, anti-insulin like growth factor 1 receptor antibody demonstrated disappointing activity. The best outcome came from irinotecan-based regimens. Targeted therapy with aaTKIs is worthy of further investigation, with immunotherapy is not recommended for off-label use.
Keywords: Ewing sarcoma; phase II; recurrent; refractory.