This is a prospective randomized clinical trial, to determine whether dose-intensive tandem Consolidation, in a randomized comparison with single cycle Consolidation, provides an event-free survival (EFS) and overall survival (OS). The study population will be high-risk patients (non-Wnt and non-Shh sub-groups) with medulloblastoma, and for all patients with central nervous system (CNS) embryonal tumors completing "Head Start 4" Induction. This study will further determine whether the additional labor intensity (duration of hospitalizations and short-term and long-term morbidities) associated with the tandem treatment is justified by the improvement in outcome. It is expected that the tandem (3 cycles) Consolidation regimen will produce a superior outcome compared to the single cycle Consolidation, given the substantially higher dose intensity of the tandem regimen, without significant addition of either short-term or long-term morbidities.

Due to the inferior response and event-free survival data of Regimens D and D2 on "Head Start III" for all children with supratentorial embryonal tumors, in comparison with the published data from "Head Start II" with Regimen A2 for metastatic patients, all such patients will receive the "Head Start II" Induction Regimen A2, on "Head Start 4", for either three or five cycles, depending upon whether or not they achieve complete remission by the end of Induction cycle #3. They will then undergo randomization to either single cycle or three tandem cycles of Consolidation marrow-ablative chemotherapy with AuHPCR.

Because of the unsatisfactory event-free survival for young children with non-desmoplastic/extensive nodular medulloblastoma (predominantly non-Shh and non-Wnt medulloblastoma subgroups) on Regimens D and D2 of "Head Start III", all these patients will receive the "Head Start II" Induction Regimen A2 on ""Head Start 4"", for either three or five cycles, depending upon whether or not they achieve complete remission by the end of Induction cycle #3. They will then undergo randomization to either single cycle or three tandem cycles of Consolidation marrow-ablative chemotherapy with AuHPCR.

Because of the excellent event-free and overall survival for young children with good risk medullo-blastoma (Shh or Wnt subgroups) treated with up-front "Head Start" chemotherapy strategies, such patients will undergo risk-tailored reduction of duration of Induction therapy from five cycles to three cycles of the "Head Start II" Induction Regimen A2 on "Head Start 4" for patients achieving a complete response to 3 cycles, followed, provided they are also without evidence of residual tumor following recovery from Induction cycle #3. They will NOT then undergo randomization, but will follow with a single cycle of Consolidation marrow-ablative chemotherapy as in "Head Start" studies.

Inclusion Criteria:

• Patients 10 years of age at the time of definitive confirmatory eligible histologic or cytologic diagnosis of eligible CNS tumor (brain or spinal cord)

• Patients may not have received irradiation or chemotherapy (except corticosteroids)

• Have histologically proven diagnosis of medulloblastoma or CNS embryonal tumors of the brain or spinal cord

• Medulloblastoma

  • Posterior fossa classic, desmoplastic or extensive nodular or anaplastic/large cell medulloblastoma with appropriate and sufficient tumor material (FFPE or snap frozen) for proposed assays: all stages, age less than 6 years at diagnosis
  • Posterior fossa classic or anaplastic/large cell medulloblastoma with sufficient tumor material (FFPE or snap frozen) for proposed assays: clinically high-stage (neuraxis or extra-neural dissemination, M1-4), age greater than 6 years to less than 10 years at diagnosis
  • Posterior fossa medulloblastoma, those 6 years of age and above at diagnosis, will only be eligible if they have evidence of neuraxis or extraneural dissemination. Patients 6 years of age and above with low-stage (standard-risk, M0) medulloblastoma will NOT be eligible for this study, irrespective of molecular subgroup and extend of local resection

• CNS Embryonal Tumors:

  - Pineoblastoma, CNS neuroblastoma, CNS ganglioneuroblastoma, embryonal tumor with multi-layered rosettes (ETMR, including embryonal tumor with abundant neuropil and true rosettes (ETANTR), ependymoblastoma and ETMR not otherwise specified), medulloepithelioma, CNS embryonal tumor with rhabdoid features (INI1 intact) and CNS embryonal tumor, not otherwise specified.

• Must commence Induction chemotherapy within 28 days of the most recent definitive surgical procedure and within 21 days of the most recent neuro-imaging studies (MRI of brain, performed with and without gadolinium contrast, and MRI of total spine, performed with gadolinium contrast) and lumbar CSF cytological examination

• Patients must have adequate organ functions at the time of registration:

  • Liver: bilirubin less than 1.5 mg/dL (except for patients with Gilbert's Syndrome of indirect hyperbilirubinemia) and transaminases [SGPT or ALT, and SGOT or AST] less than 2.5 (two and a half) times the upper limits of institutional normal.

  • Renal: Creatinine clearance and/or glomerular filtration rate (GFR) greater than or equal to 60 mL/min/1.73m² within 21 days of protocol therapy.

  • Bone Marrow Function:

    1. Peripheral absolute phagocyte count (APC) > 1000/ µL. APC = numbers of banded neutrophils + segmented neutrophils + metamyelocytes + monocytes + eosinophils Please note, if institution reports differential as a percentage, then APC = [percentage of banded neutrophils + segmented neutrophils+ metamyelocytes+monocytes+eosinophils] x total white cell count.
    2. Platelet Count > 100,000/µL (transfusion independent)
    3. Hemoglobin > 8 gm/dL (may have received RBC transfusions).

Exclusion Criteria:

• Patients older than 10 years of age at time of diagnosis
• Following diagnoses are not eligible for study enrollment: CNS atypical teratoid/rhabdoid tumor (AT/RT); all ependymomas including anaplastic ependymomas of the brain or spinal cord; all choroid plexus carcinomas; all high-grade glial and glio-neuronal tumors; all primary CNS germ cell tumors; all primary CNS sarcomas; all primary or metastatic CNS lymphomas and solid leukemic lesions (i.e., chloromas, granulocytic sarcomas).
• Patients with unbiopsied diffuse intrinsic pontine tumors will NOT be eligible for this study.