A Study of Romiplostim to Prevent Low Platelet Counts in Children and Young Adults Receiving Chemotherapy for Solid Tumors

Inclusion Criteria: * Documented diagnosis of a primary solid tumor. Patients must have histological verification of malignancy at MSKCC. * Male and female patients aged 1-21 years with a primary solid tumor undergoing treatment with the pre-defined chemotherapy regimens of EFT, MAP, D9803. Prior to enrollment patient could have been undergoing induction therapy with a similarly myelosuppressive regimen as long as they will be continuing with EFT, MAP, D9803 at the time of study enrollment. * Patients undergoing treatment with MAP chemotherapy w ho have had ≥ 1 platelet transfusion during induction stage of treatment. * Total Bilirubin (sum of conjugated + unconjugated) ≤ 3 times institutional upper limit of normal (ULN) for age and ALT/AST ≤ 3 times institutional ULN for age. * Normal cardiac function: * Shortening fraction greater than or equal to 28% by echocardiogram OR Left ventricular ejection fraction (LVEF) greater than or equal to 50% on technetium- 99m pertechnetate radionuclide cineangiography (MUGA) or echocardiogram. * Screening ECG with corrected QT (QTc) interval of \< 470 msec. * Timing of cardiac assessment: We will utilize the most recent EKG/ECHO when assessing cardiac function. See section 9.0 for additional details. * Adequate renal function, defined as an estimated Creatinine Clearance or GFR \>40ml/min or an normal creatine for age (see below) Serum Creatinine by age: Age (years) \<6: Maximum Serum Creatinine (mg/dL), Male 0.8, Female 0.8 Age …