Irinotecan and Temozolomide in Combination With Existing High Dose Alkylator Based Chemotherapy for Treatment of Patients With Newly Diagnosed Ewing Sarcoma

Inclusion Criteria: * Age greater than or equal to one year and less than or equal to 40 years at the time of diagnosis * Newly diagnosed, previously untreated patients with histologically or molecularly confirmed Ewing sarcoma * Adequate hematologic function: * Absolute neutrophil count ≥ 1,000/K/mcl * Platelet count ≥ 100,000/Kmcl * Adequate renal function: * Normal creatinine for age (See table below) OR * Creatinine clearance or radioisotope GFR ≥ 70ml/min/1.73 m2 Age(Years) Maximum Serum Creatinine (mg/dL) ≤ 5 0.8 6 to ≤ 10 1 11 to ≤ 15 1.2 ≥ 16 1.5 Adequate hepatic function: * Total bilirubin ≤ 1.5 x the ULN * AST ≤ 2.5 x the ULN \[in the absence of hepatic involvement of tumor. Patients with hepatic involvement are considered eligibile for study\] * ALT ≤ 2.5 x the ULN \[in the absence of hepatic involvement of tumor. Patients with hepatic involvement are considered eligibile for study\] Normal cardiac function: * Shortening fraction ≥ 28% by echocardiogram OR * Left ventricular ejection fraction (LVEF) ≥ 50% on technetium- 99m pertechnetate radionuclide cineangiography (MUGA) or echocardiogram * Patients must consent to an indwelling central venous catheter. * Sexually active patients of reproductive potential must be willing to use an effective method of contraception. Exclusion Criteria: * Prior chemotherapy or radiotherapy (other than limited, emergent radiotherapy for treatment of eg. spinal cord compromise or threatened airway) * Pregnant or breastfeeding females