Fosaprepitant in Patients Receiving Ifosfamide-based Regimen

150 mg administered intravenously, delivered in either single dose or two doses, on Day 1 for single dose and on Days 1 and 4 for two doses, varying between Cycle 1 or Cycle 2 depending upon randomization to arm.

Intravenous push (IVPB) daily for 5 days (12 mg on day 1, and 8 mg on days 2-5)

5HT3 receptor antagonist as standard of care 30 minutes prior to chemotherapy

Doxorubicin + Mesna + + Ifosfamide + Vincristine, chemotherapy cycles repeated every 3-4 weeks for up to 6 cycles. Chemotherapy drugs listed separately, individual dosages, etc.

25 mg/m\^2/day IV continuous infusion for 72 hours on days 1, 2, and 3, completing infusion on day 4 (total dose: 75 mg/m\^2) as part of AI Chemotherapy.

Prior to ifosfamide (Day 1) - 500 mg/m\^2 (20% of ifosfamide dose) given simultaneously with ifosfamide and then daily continuous infusion (Days 1-4 completing infusion on day 4) - 1,500 mg/m\^2/day (60% of daily ifosfamide dose) for a total of 6 gm/m\^2. The mesna infusion complete 24 hours after last dose of ifosfamide.

2.5 g/m\^2 IV bolus over 3 hours on days 1, 2, 3, 4 (total dose: 10 g/m\^2).

2 mg IV by rapid infusion (Day 1) may be given to participants with sarcomas of small cell histology.