Background
Phase III combined analysis of Euro-E.W.I.N.G.99 (R3, n=281) and Ewing-2008 (R2, n=190), N=471, localized high-risk Ewing sarcoma (tumour volume ≥200 mL, poor histologic response <90% necrosis after VIDE, or central pelvic primary). All received VIDE induction ×6; randomized to high-dose busulfan+melphalan (BuMel) with autologous stem-cell rescue vs conventional VAI/VAIA consolidation. European Ewing Tumour Working Initiative.
Interventions and follow up
Arm A: Standard VAI consolidation (vincristine, doxorubicin/dactinomycin, ifosfamide) ± radiotherapy
Arm B: High-dose busulfan + melphalan (BuMel) with autologous stem-cell rescue
Primary endpoint: Event-free survival (EFS)
mFollow up: ~8 yr (combined analysis)
Arm B: High-dose busulfan + melphalan (BuMel) with autologous stem-cell rescue
Primary endpoint: Event-free survival (EFS)
mFollow up: ~8 yr (combined analysis)
Results
8-yr EFS: numerically improved with HDCT (~59% vs ~48% standard, combined analysis)
OS: 8-yr trend favoring HDCT, not statistically significant
Subgroup: exploratory analysis — very high-risk features (large volume or poor response) showed greater relative HDCT benefit
OS: 8-yr trend favoring HDCT, not statistically significant
Subgroup: exploratory analysis — very high-risk features (large volume or poor response) showed greater relative HDCT benefit
Adverse events
HDCT (BuMel+ASCT): higher treatment-related morbidity; toxic deaths ~3–4%; severe mucositis, hepatic veno-occlusive disease (SOS/VOD), prolonged cytopenias, infection, late endocrine effects
Standard VAI: lower acute toxicity
Late effects (HDCT): high infertility, endocrinopathy, elevated secondary-malignancy risk
Standard VAI: lower acute toxicity
Late effects (HDCT): high infertility, endocrinopathy, elevated secondary-malignancy risk
Conclusions
High-dose BuMel+ASCT showed numerically improved EFS vs standard VAI consolidation in high-risk localized Ewing sarcoma, particularly in very high-risk exploratory subgroups. Results do not definitively establish superiority across all high-risk patients; substantial toxicity must be weighed. HDCT remains an option in selected very high-risk patients at specialized centers.
Key Limitations
Combined analysis of two protocols with differing randomizations; EFS/OS differences not statistically significant; benefit confined to exploratory subgroups; toxic deaths and severe late effects from HDCT; no molecular risk stratification.
Clinical Context
Informed European practice favoring BuMel consolidation for selected high-risk localized Ewing sarcoma per ESMO; North American (COG) practice generally retains interval-compressed VDC/IE without routine HDCT. Highlights transatlantic divergence in consolidation strategy.