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

Inclusion Criteria:

* Subjects with histologically confirmed CNS embryonal tumor (primitive neuroectodermal tumor \[PNET\], medulloblastoma, atypical teratoid rhabdoid tumor \[ATRT\], medulloepithelioma, pineoblastoma or ependymoblastoma), or germ cell tumor, are eligible; subjects may be enrolled on study as first-line treatment; diagnosis will be made on the basis of computed tomography (CT)-assisted or stereotactic biopsy, open biopsy, surgical resection, cerebrospinal fluid (CSF) cytology, or elevated tumor markers
* Subjects may be enrolled as part of first-line treatment; those subjects who enroll as first-line treatment will not be restricted from traditional treatments in the future; at least 14 days must have elapsed since completion of cranial radiotherapy and 28 days since completion of chemotherapy; at least 28 days must have elapsed since completion of total spine radiotherapy
* Subjects with no previous radiotherapy treatment must have a consultation with a radiation oncologist or providers must have a discussion in the context of Neuro-Oncology Tumor Board within 60 days prior to start of IA/BBBD chemotherapy to determine the need for radiotherapy prior to or after IA/BBBD
* Glomerular filtration rate (GFR) or creatinine clearance (CrCl) (24 hour urine) greater than 30 ml/min corrected for body surface area
* Absolute granulocyte count \>= 1.0 x 10\^3/mm\^3
* Platelets \>= 100 x 10\^3/mm\^3
* Creatinine \< 1.5
* Total bilirubin \< 2.0 mg/dl
* Aspartate aminotransferase (AST)/alanine aminotransferase (ALT) \< 2.5 x upper limits of normal
* Subject's Karnofsky performance status (KPS) must be \>= 50% (Eastern Cooperative Oncology Group \[ECOG\] performance score \< 3)
* Subjects or their legal guardian must sign a written informed consent in accordance with institutional guidelines
* Sexually active women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study treatment and for the duration of study treatment; should a female become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately
* For the phase II portion of the study, subjects must have disease that is evaluable for response; subjects who have had radiation to all sites of disease are not eligible unless there is imaging evidence of active tumor, ie: increased blood volume

Exclusion Criteria:

* Subjects with radiographic signs of excessive intracranial mass effect with associated rapid neurologic deterioration and/or spinal cord block
* Subjects at significant risk with general anesthesia
* Subjects with uncontrolled (over the last 30 days) clinically significant confounding medical conditions
* Subject is pregnant or is lactating
* Subjects who have contraindications to carboplatin, melphalan, or STS