Safety Study for Refractory or Relapsed Neuroblastoma With DFMO Alone and in Combination With Etoposide

Inclusion Criteria: * Age: 0-21 years at the time of diagnosis. * Diagnosis: Histologic verification at either the time of original diagnosis or relapse of neuroblastoma. * Disease Status: Refractory or relapsed neuroblastoma * Measurable disease, including at least one of the following: Measurable tumor \>10mm by CT or MRI A positive MIBG and abnormal urinary catecholamine levels Positive bone marrow biopsy/aspirate. * Current disease state must be one for which there is currently no known curative therapy. * A negative urine pregnancy test is required for female subjects of child bearing potential (onset of menses or ≥13 years of age). * Patients without bone marrow metastases must have an ANC \> 500/μl and platelet count \>50,000/μl * Organ Function Requirements Subjects must have adequate liver function as defined by AST or ALT \<10x normal Serum bilirubin must be ≤ 2.0 mg/dl Serum creatinine must be ≥ 1.5 mg/dl * Informed Consent: All subjects and/or legal guardians must sign informed written consent. Assent, when appropriate, will be obtained according to institutional guidelines Exclusion Criteria: * Life expectancy \<2 months or Lansky score \<30% * Investigational Drugs: Subjects who are currently receiving another investigational drug are excluded from participation. * Anti-cancer Agents: Subjects who are currently receiving other anticancer agents are not eligible. Subjects must have fully recovered from the effects of prior chemotherapy (hematological and bone marrow suppression effects) * Infection: Subjects who have an uncontrolled infection are not eligible until the infection is judged to be well controlled in the opinion of the investigator. * Subjects who, in the opinion of the investigator, may not be able to comply with the safety monitoring requirements of the study, or in whom compliance is likely to be suboptimal, should be excluded.