Combination Chemotherapy in Treating Patients With Newly Diagnosed Metastatic Ewing's Sarcoma or Primitive Neuroectodermal Tumor

OBJECTIVES: I. Evaluate the response rate and duration of response of patients with newly diagnosed, metastatic Ewing's sarcoma or primitive neuroectodermal tumor treated with maximally intensified VAdrC (vincristine, doxorubicin, cyclophosphamide) alternating with IE (ifosfamide, etoposide). II. Evaluate the response to new agents (first topotecan, then topotecan with cyclophosphamide) utilized in an upfront treatment window. III. Assess the role of surgery with regard to local control of primary and metastatic sites and disease course. IV. Evaluate whether individual variability in ifosfamide and cyclophosphamide metabolism correlates with toxicity and/or response. V. Evaluate the rise in the absolute neutrophil count following one dose of filgrastim (G-CSF) given immediately prior to a chemotherapy course as an indicator of bone marrow reserve and subsequent myelosuppression. VI. Determine if amifostine provides significant chemo-radio protection, particularly against the cumulative toxicities of this intensive therapy. OUTLINE: This is a partially randomized, multicenter study. Patients are treated on the investigational window first or proceed to induction therapy immediately, if aggressive treatment is necessary. INVESTIGATIONAL WINDOW: Patients receive cyclophosphamide IV and topotecan IV over 30 minutes on days 1-5. Filgrastim (G-CSF) is administered subcutaneously (SQ) beginning day 6 until blood cell counts recover. Treatment is repeated at week 3. INDUCTION THERAPY: Patients over 12 months old are randomized to receive amifostine or not. Patients receive etoposide IV over 45 minutes and ifosfamide IV over 2 hours on days 1-5. Amifostine IV over 15 minutes is also administered prior to ifosfamide. Patients receive G-CSF SQ (or IV over 2 hours) beginning on day 6. This course of treatment is administered on weeks 6, 12, and 18. Patients receive the VAdrC chemotherapy regimen on weeks 9 and 15. This regimen consists of vincristine IV and amifostine IV over 15 minutes on days 1, 8, and 15, cyclophosphamide IV over 30 minutes and doxorubicin IV over 48 hours on days 1 and 2, and G-CSF beginning on day 3. The VAdrC regimen is continued during local therapy on weeks 21-29 and 39-47, except the day 15 dose of vincristine is omitted, cyclophosphamide is administered on day 1 only on weeks 21, 24, 27, 39, 42, and 45, and doxorubicin is replaced with etoposide IV over 60 minutes on days 1-3 on weeks 24, 28, 42, and 45. Local therapy begins after 21 weeks of chemotherapy. Patients who respond to chemotherapy and have resectable disease undergo a complete resection with negative margins. Patients with unresectable disease or bulky lesions undergo radiotherapy. Some patients may undergo both surgery and radiotherapy. Local therapy of metastases is delayed until after week 39. Patients are followed every 3 months for 1 year, every 6 months for 2 years, then annually thereafter.