Study of Nifurtimox to Treat Refractory or Relapsed Neuroblastoma or Medulloblastoma

This study is being done to test the effect of a drug, nifurtimox, against neuroblastoma and medulloblastoma in children. Nifurtimox is a drug that has been used in South America for many years to treat a parasitic disease known as Chagas Disease. It is not approved by the Food and Drug Administration for routine use in neuroblastoma or medulloblastoma in the United States, but limited early observations suggest that nifurtimox may have anti tumor activity for neuroblastoma and medulloblastoma. From the preliminary trials of nifurtimox we have determined a safely tolerated dose of nifurtimox to use in neuroblastoma patients (30mg/kg/day). The dose determined in the Phase I study to be safe, will be the dose used for this study. From clinical experience in South America, we know that children can tolerate nifurtimox when given by mouth, and it appears to have no long-term side effects when used to treat Chagas Disease. Based on our laboratory and animal studies, we believe that drug levels similar to those used to treat Chagas Disease may shrink/kill neuroblastoma cells, especially when combined with other chemotherapy drugs. We do not know whether nifurtimox will shrink/kill tumor cells effectively in children. Therefore, the major goal of the study is to learn if nifurtimox in combination with other chemotherapy drugs is effective in shrinking/killing neuroblastoma and medulloblastoma cells.