Comparison of Chemotherapy Regimens in Treating Children With Relapsed or Progressive Rhabdomyosarcoma

OBJECTIVES: I. Compare response rate in children with relapsed or progressive rhabdomyosarcoma, undifferentiated sarcoma, or ectomesenchymoma treated with 2 different schedules of irinotecan and vincristine in an upfront phase II window. II. Determine the progression-free and overall survival of patients treated with multiagent chemotherapy. III. Determine the toxic effects of tirapazamine, doxorubicin, and cyclophosphamide in these patients. IV. Determine the toxic effects of irinotecan and vincristine in these patients. V. Determine whether conversion of irinotecan to its active metabolite SN-38 predicts tumor response in these patients. OUTLINE: This is a randomized, multicenter study. Patients are stratified according to risk status and window therapy eligibility (unfavorable risk and eligible vs unfavorable risk and ineligible vs favorable risk). UNFAVORABLE-RISK PATIENTS ELIGIBLE FOR WINDOW THERAPY: Patients are stratified according to prior topotecan (yes vs no). These patients are randomized to 1 of 2 treatment arms. ARM I: Patients receive vincristine IV on days 1 and 8 and irinotecan IV over 1 hour on days 1-5 and 8-12. Treatment repeats every 21 days for 2 courses in the absence of disease progression or unacceptable toxicity. ARM II: Patients receive vincristine IV on days 1 and 8 and irinotecan IV over 1 hour on days 1-5. Treatment repeats every 21 days for 2 courses in the absence of disease progression or unacceptable toxicity. Patients in both arms with partial response (PR) or complete response (CR) receive 5 additional courses of irinotecan and vincristine on the previous schedule. In addition, patients with PR or CR also receive cyclophosphamide/doxorubicin (CD) and ifosfamide/etoposide (IE) chemotherapy. CD/IE CHEMOTHERAPY: Patients receive cyclophosphamide IV over 1 hour and doxorubicin IV over 15-30 minutes on day 1 of weeks 7, 16, 28, 37, and 40. Patients also receive ifosfamide IV over 1 hour and etoposide IV over 1 hour on days 1-5 of weeks 10, 19, 22, 31, and 43. Treatment continues in the absence of disease progression or unacceptable toxicity. Patients with no response or progressive disease on arm I or II proceed to tirapazamine/cyclophosphamide/doxorubicin (TCD) and ifosfamide/etoposide (IE) chemotherapy. TCD/IE CHEMOTHERAPY: Patients receive tirapazamine IV over 2 hours, cyclophosphamide IV over 1 hour, and doxorubicin IV over 15-30 minutes on day 1 of weeks 7, 10, 16, 25, and 34. Patients also receive ifosfamide IV over 1 hour and etoposide IV over 1 hour on days 1-5 of weeks 13, 19, 22, 28, 31, and 37. PATIENTS WITH UNFAVORABLE RISK AND INELIGIBLE FOR WINDOW THERAPY: Patients receive tirapazamine IV over 2 hours, cyclophosphamide IV over 1 hour, and doxorubicin IV over 15-30 minutes on day 1 of weeks 1, 4, 10, 19, and 28. Patients also receive ifosfamide IV over 1 hour and etoposide IV over 1 hour on days 1-5 of weeks 7, 13, 16, 22, 25, and 31. Patients also receive filgrastim (G-CSF) or sargramostim (GM-CSF) subcutaneously (SC) beginning 1 day after each course of chemotherapy and continuing until blood counts recover. Treatment continues in the absence of disease progression or unacceptable toxicity. PATIENTS WITH FAVORABLE RISK: Patients receive cyclophosphamide IV over 1 hour and doxorubicin IV over 15-30 minutes on day 1 of weeks 1, 4, 10, 19, and 28. Patients also receive ifosfamide IV over 1 hour and etoposide IV over 1 hour on days 1-5 of weeks 7, 13, 16, 22, 25, and 31. Patients also receive G-CSF or GM-CSF SC beginning 1 day after each course of chemotherapy and continuing until blood counts recover. Treatment continues in the absence of disease progression or unacceptable toxicity. Patients are followed every 2 months for 1 year, every 4 months for 2 years, and then annually thereafter.