10546 Background: High-dose chemotherapy (HDC) is widely used in consolidation treatment of Ewing sarcoma patients with primary disseminated or recurrent disease. Standard busulfan-based regimens are not compatible with radiotherapy to central axis sites. Treosulfan is a newly-developed bifunctional alkylating agent that has been shown to be safe in current trials of the German Society for Pediatric Hematology and Oncology (GPOH) even in heavily pre-treated patients including axial radiation. Methods: Event-free survival (EFS) and overall survival (OS) for 21 patients with primary disseminated disease (PDD) and survival after relapse for 11 relapse patients recruited from the EURO-E.W.I.N.G.99 trial 1998–2007 were analyzed. PDD-patients had received VIDE induction prior to treosulfan-based HDC (treosulfan: 36g/m2; melphalan: 140mg/m2) followed by autologous stem cell transplantation. Median follow up was 1.72 yrs. Relapse patients had received appropriate second line chemotherapy regimens prior to treosulfan-based HDC. Median follow up after relapse was 2.26 yrs. Results: Seventeen of 21 (81%) PDD-patients had a central axis site of the primary tumor, 8 patients (38%) presented with a pelvic tumor. Metastatic sites were: bone (76%), bone marrow (22%), CNS (10%), liver (15%), lymphnode (29%), other (16%), and additionally lung metastases in 57%. 1y-EFS was 0.70 (SE=.10), 2y-EFS was 0.27 (SE=0.10), and 3y-EFS was 0.16 (SE=.09). 1y-OS was 0.84 (SE=.08), 2y-OS was 0.46 (SE=.13), and 3y-OS was 0.32 (SE=.12). In the cohort of 11 relapse patients two patients (18%) had a local relapse, 3 (27%) a combined relapse, and 6 (55%) a systemic relapse. Six of 11 (55%) relapse patients had a late relapse >2 yrs from diagnosis. Survival after relapse at 3yrs was 0.70 (SE=.15). Conclusions: Treosulfan-based HDC is an alternative approach in high-risk Ewing tumor patients especially after relapse to consolidate a second remission. Further investigation and comparison to other standard HDC regimens is needed. No significant financial relationships to disclose.
High-dose chemotherapy followed by autologous haematopoietic cell transplantation for children, adolescents, and young adults with first recurrence of Ewing sarcoma
