Longer versus Shorter Schedules of Vincristine, Irinotecan, and Temozolomide (VIT) for Relapsed or Refractory Ewing Sarcoma: A Randomized Controlled Phase 2 Trial

PURPOSE: The optimal dose schedule of vincristine, irinotecan, and temozolomide (VIT) in relapsed or refractory patients with Ewing sarcoma requires clarification. PATIENTS AND METHODS: Patients with relapsed or refractory Ewing sarcoma were randomly assigned (1:1) to either a shorter d × 5 schedule (irinotecan 50 mg/m2/d D1-5, vincristine 1.4 mg/m2 D1) or protracted d × 5×2 schedule (irinotecan 20 mg/m2/d D1-5,8-12, vincristine 1.4 mg/m2 D1,8) together with temozolomide (100 mg/m2/d D1-5). Patients were treated every 3 weeks for up to eight cycles until progression or unacceptable toxic effects occurred. The primary endpoint was objective response rate at 12 weeks (ORR12w). Secondary endpoints were progression-free survival (PFS), overall survival (OS), and safety. RESULT: A total of 46 patients presenting with relapsed or refractory Ewing sarcoma were randomly assigned to the d × 5 (n = 24) or d × 5×2 (n = 22) schedules. Median follow-up was 10.7 months in the d × 5 group and 8.3 months in the d × 5×2 group. ORR12w was lower for d × 5 (5/24; 20.8%) patients than for d × 5×2 (12/22; 54.5%; P = 0.019), but no significant difference was found in PFS (median PFS, 2.3 months for d × 5 vs. 4.3 months for d × 5×2) or OS (median OS, 14.8 months for d × 5 and 12.8 months for d × 5×2). Patients receiving the d × 5 schedule reported more grade 3 and 4 adverse events (AE) than those receiving d × 5×2, including diarrhea/abdominal pain and vomiting/nausea. CONCLUSIONS: The protracted d × 5×2 VIT schedule showed superior efficacy and favorable tolerability compared with the shorter d × 5 VIT schedule in patients with relapsed or refractory Ewing sarcoma.