HSV G207 Alone or With a Single Radiation Dose in Children With Progressive or Recurrent Supratentorial Brain Tumors

Inclusion Criteria: * Age ≥ 36 months and \< 19 years * Pathologically proven malignant supratentorial brain tumor (including glioblastoma multiforme, giant cell glioblastoma, anaplastic astrocytoma, primitive neuroectodermal tumor, ependymoma, atypical teratoid/rhabdoid tumor, germ cell tumor, or other high-grade malignant tumor) which is progressive or recurrent despite standard care including surgery, radiotherapy, and/or chemotherapy. A pathologically proven secondary malignant tumor without curative treatment options is eligible. * Lesion must be \> 1.0 cm in diameter and surgically accessible as determined by MRI * Patients must have fully recovered from acute treatment related toxicities of all prior chemotherapy, immunotherapy or radiotherapy prior to entering this study. * Myelosuppressive chemotherapy: patients must have received their last dose at least 3 weeks prior (or at least 6 weeks if nitrosurea) * Investigational/Biologic agents: patients must have recovered from any acute toxicities potentially related to the agent and received last dose ≥ 7 days prior to entering this study (this period must be extended beyond the time during which adverse events are known to occur for agents with known adverse events ≥ 7 days). For viral therapy, patients must have received viral therapy ≥ 3 months prior to study entry and have recovered from all acute toxicities potentially related to the agent * Monoclonal antibodies: patient must have received last dose ≥ 21 days prior * Radiation: Patients must have received their last fraction of craniospinal radiation (\>24 Gy) or total body irradiation ≥ 3 months prior to study entry. Patients must have received focal radiation to symptomatic metastatic sites or local palliative radiation \> 28 days prior to study entry. * Autologous bone marrow transplant: Patients must be ≥ 3 months since transplant prior to study entry. * Normal hematological, renal and liver function (Absolute neutrophil count \> 1000/mm3, Platelets \> 100,000/mm3, Prothrombin Time (PT) or Partial Thromboplastin Time (PTT) \< 1.3 x control, Creatinine within normal institutional limits OR \> 60 mL/min/1.73 m2 for patients with creatinine levels above institutional normal, Total Bilirubin \< 1.5 mg/dl, Transaminases \< 3 times above the upper limits of the institutional norm) * Patients \< 10 years, Modified Lansky score ≥ 60; patients \> 10 years, Karnofsky score ≥ 60 * Patient life expectancy must be at least 8 weeks * Written informed consent in accordance with institutional and FDA guidelines must be obtained from patient or legal guardian Exclusion Criteria: * Acute infection, granulocytopenia or medical condition precluding surgery * Pregnant or lactating females * Prior history of encephalitis, multiple sclerosis, or other central nervous system (CNS) infection * Tumor involvement which would require ventricular, cerebellar or brainstem inoculation or would require access through a ventricle in order to deliver treatment * Required steroid increase within 1 week prior to injection * Known HIV seropositivity * Concurrent therapy with any drug active against HSV (acyclovir, valaciclovir, penciclovir, famciclovir, gancyclovir, foscarnet, cidofovir) or any immunosuppressive drug therapy (except dexamethasone or prednisone).