Melphalan, Carboplatin, Mannitol, and Sodium Thiosulfate in Treating Patients With Recurrent or Progressive CNS Embryonal or Germ Cell Tumors

central nervous system embryonal neoplasm, embryonal tumor with multilayered rosettes, c19mc-altered, germ cell tumor, medulloblastoma, medulloepithelioma, primitive neuroectodermal tumor, recurrent childhood central nervous system embryonal neoplasm, recurrent malignant germ cell tumor, recurrent medulloblastoma, recurrent primitive neuroectodermal tumor, interventional, phase1