Sorafenib in Treating Young Patients With Relapsed or Refractory Solid Tumors or Leukemia

Inclusion Criteria: * Diagnosis of 1 of the following: * Histologically confirmed malignant solid tumor at original diagnosis or relapse * Measurable or evaluable disease by CT scan or MRI * Histologically confirmed leukemia, including 1 of the following: * Acute lymphoblastic leukemia (ALL) * Greater than 25% blasts in the bone marrow (M3 bone marrow) * Acute myeloid leukemia (AML) * Greater than 25% blasts in the bone marrow (M3 bone marrow) * AML and FLT3-ITD mutation * Patients must have ? 5% blasts in the bone marrow * Active extramedullary disease (except leptomeningeal disease) allowed * Juvenile myelomonocytic leukemia (JMML) meeting the following criteria: * Peripheral blood monocytosis \> 1,000/mm\^3 * Blasts (including promonocytes) are \< 20% of the WBCs in the blood and of the nucleated bone marrow cells * No Philadelphia chromosome (Ph) or BCR/ABL fusion gene * Has ? 2 of the following additional diagnostic criteria: * Hemoglobin F increased for age * Immature granulocytes in the peripheral blood * WBC \> 10,000/mm\^3 * Clonal chromosomal abnormality (e.g., may be monosomy 7) * Sargramostim (GM-CSF) hypersensitivity of myeloid progenitors in vitro * Chronic myelogenous leukemia (CML) in blast crisis * Greater than 25% blasts in the bone marrow (M3 bone marrow) * Patients with Ph-positive CML must be refractory to imatinib mesy…