Intensified Induction Therapy for Newly Diagnosed, Localized Skeletal Ewing Sarcoma (ISG/AIEOP EW‐1): A Randomized, Open‐Label, Phase 3, Non‐Inferiority Trial

ABSTRACT Background Several studies have shown that the intensity of treatment in Ewing sarcoma has an impact on outcome. The present trial tested the non‐inferiority of intensive, shorter, induction chemotherapy (25 weeks total treatment time) compared to the standard treatment (37 weeks) in non‐metastatic Ewing sarcoma (ES) at onset. Procedure This national, multicenter, parallel, randomized, controlled, open‐label, non‐inferiority, phase III trial was conducted in 14 specialized hospitals in Italy. Patients aged 2‐40 years with newly diagnosed localized ES were randomized to receive four courses of induction therapy (one every 21 days) either with a standard arm (Arm A) or with an intensive arm (Arm B). For consolidation therapy, good responders (GRs) in Arm A received nine courses (37 weeks), while Arm B patients received five courses (25 weeks). Poor responders for both arms received four courses followed by high‐dose busulfan/melphalan + autologous stem cell rescue. Follow‐up was 5 years. Results In the study period 2009–2018, 274 patients with ES at onset were screened, 248 were eligible, 15 refused randomization, and 233 were randomized (Arm A: 113; Arm B: 120). Median age was 14 years. Arm B was not inferior to Arm A: 5‐year EFS was 77.5% and 71.6%, respectively (HR vs. Arm A: 0.74, 90% CI: 0.49–1.14). GRs were 54.9% in Arm A and 62.5% in Arm B. Hematological, gastrointestinal, and cardiovascular Grade ≥3 toxicities had higher frequencies in Arm B. Conclusions Intensive induction therapy showed non‐inferiority in 5‐year EFS when compared with the standard induction therapy. Higher toxicity was reported in Arm B with similar outcome, counterbalanced in GRs with a shorter treatment plan. ClinicalTrials.gov Identifier: NCT02063022.