Combination Intraventricular Chemotherapy Pilot Study: 5-Azacytidine (5-AZA) and Trastuzumab Infusions Into the Fourth Ventricle or Resection Cavity in Children and Adults with Recurrent or Residual Posterior Fossa Ependymoma

Inclusion Criteria: * Patients with histologically verified ependymoma, with recurrence or progression anywhere in the brain and/or spine. Patients are also eligible if they have refractory disease, which will be defined as residual tumor which has not been completely cleared despite prior treatments. To be eligible, patients' disease must have originated in the posterior fossa of the brain * Patient must have either measurable or evaluable tumor as assessed by MRI of the brain and total spine * An implanted catheter in the fourth ventricle or posterior fossa tumor cavity attached to a ventricular access device or agreement to have one placed. * A minimum of 4 weeks between any prior radiation treatments or bevacizumab infusions and first infusion of 5-azacytidine or trastuzumab infusions. A minimum of 2 weeks between last dose of any other systemic chemotherapy and first infusion of 5-azacytidine or Trastuzumab into fourth ventricle * Life expectancy of at least 12 weeks in the opinion of the principal investigator * Lansky score of 50 or greater if ≤16 years of age or Karnofsky score of 50 or greater if \> 16 years of age * Existing neurological deficits must have been stable for a minimum of 1 week prior to study enrollment * Patients must have recovered from the acute toxic effects of all prior anticancer chemotherapy * Adequate bone marrow function defined by peripheral absolute neutrophil count (ANC) ≥ 500/µL, platelet count ≥ 50,000/µL (transfusion independent), and hemoglobin ≥ 9.0 gm/dL (may receive red blood cell (RBC) transfusions) * Patient or patient's legal representative, parent(s), or guardian able to provide written informed consent. * Patient with abnormal cardiac function (Shortening fraction less than 28% on echocardiogram) will need cardiology clearance prior to enrollment * Normal renal and liver function on basic metabolic panel. Any patients with abnormal blood urea nitrogen (BUN), creatinine, alanine aminotransferase(AST) or aspartate aminotransferase (ALT) levels will need nephrology and/or gastroenterology clearance prior to enrollment Exclusion Criteria: * Enrolled in another treatment protocol * Patients with disease that is completely resectable * Has received another investigational or chemotherapy agent within 2 weeks or radiation therapy within 4 weeks prior to 5-azacytidine or trastuzumab infusion into the fourth ventricle * Patients with any cardiac issues who are not cleared by cardiology for participation in the study * Evidence of untreated infection * Pregnant or lactating women