Background: In Children’s Oncology Group trial AEWS0031, VAC alternating with IE administered every 2 weeks rather than every 3 weeks resulted in a superior event-free survival (EFS). In the 2-week dosing group, a median interval of 15 days (mean 17.3) was achieved. Only 12% of patients enrolled in the trial were age 18+ and thus the feasibility of interval-compressed VAC/IE in the adult population remains poorly described. We conducted a retrospective analysis of our institutional experience using this regimen. Methods: Pharmacy administration records at Oregon Health and Science University were reviewed to identify patients age 18+ with Ewing and Ewing-like sarcoma who received VAC/IE q2wk, with first dose between January 2011 and March 2018. Results: 24 patients were identified. Median age was 28 (range 18 to 60). At diagnosis, 67% had localized disease. The most common primary sites were extremity (38%) and pelvis (17%); another 25% had extra-osseous primary tumors. Local therapy included surgery in 50% and XRT in 33% of subjects. The median interval between cycles was 16.7 days (mean 17.5). The median number of admissions for toxicity per patient was 2. The median number of dose delays (toxicity prolonging the 2 week interval) per patient was 4. Early treatment discontinuation occurred in 17%. Cumulative doses are outlined in Table. 5-year overall survival was 41%. 5-year EFS was 52% among patients with localized disease and 0% among those with metastatic disease. Conclusions: For adults with Ewing and Ewing-like sarcoma, chemotherapy administered every 2 weeks is a feasible and effective therapy, without significant dose reductions required. Our results are comparable to prior studies involving a primarily pediatric population.

*Total planned dose: doxorubicin 375 mg/m2, cyclophosphamide 8400 mg/m2, ifosfamide 63 g/m2, etoposide 3500 mg/m2.