Outcome of patients with relapsed or progressive Ewing sarcoma enrolled on cooperative group phase 2 clinical trials: A report from the Children's Oncology Group.

SevenChildren's Oncology Group phase 2 trials for patients with relapsed/progressive solid tumors were analyzed to estimate the event-free survival (EFS) for relapsed/progressive Ewing sarcoma. One hundred twenty-eight Ewing sarcoma patients were enrolled and 124 events occurred. The 6-month EFS was 12.7%, demonstrating the poor outcome of these patients. Only docetaxel achieved its protocol-specified radiographic response rate for activity; however, the EFS for docetaxel was similar to other agents, indicating that a higher radiographic response rate may not translate into superior disease control. This EFS benchmark could be utilized as an additional endpoint in trials for recurrent Ewing sarcoma.