Decitabine Followed by a Cancer Antigen Vaccine for Patients With Neuroblastoma and Sarcoma

Inclusion Criteria: * Confirmed diagnosis of relapsed high-risk neuroblastoma,Ewings sarcoma, osteogenic sarcoma, rhabdomyosarcoma, synovial sarcoma * Patient may have gross tumor that has been treated with multi-agent chemotherapy prior study entry, but does not need to have gross tumor prior to study entry. * Patients must have had a diagnosis of neuroblastoma or sarcoma either by histological verification of neuroblastoma and/or demonstration of tumor cells in the bone marrow with increased urinary catecholamines. * Have received standard chemotherapy and/or SCT, and are at least 6 months post-transplant. * Age: Patients must be 1 - \< 25 years of age when registered on study. * Organ Function Requirements: All patients must have adequate organ function defined as: * Hematological Function: ANC ≥ 500; Platelet count ≥ 75. * Renal Function: Creatinine clearance or radioisotope GFR ≥ 70ml/min/1.73 m2 OR A maximum serum creatinine (mg/dL) based on age/gender as follows: 1YO M\&F = 0.6, 2-5YO M\&F = 0.8, 6-9YO M\&F = 1, 10-12YO M\&F = 1.2, 13-15YO M = 1.5, 13-15YO F = 1.4, 16+ M = 1.7, 16+ F = 1.4 * Cardiac Function: Patient must have normal cardiac function documented by Ejection fraction (\> 55%) documented by echocardiogram or radionuclide MUGA evaluation OR Fractional shortening (≥ 28%) documented by echocardiogram * Liver Function: Total bilirubin ≤ 1.5 x normal for age, AND SGPT (ALT) and SGOT (AST) ≤ 3 x normal for age. * Room air pulse oximetry \>94%. * Male and female sexually active patients of reproductive age who wish to participate must agree to use acceptable contraception. * Lansky performance scale \> 70, ECOG \< 2 (Appendix I). Exclusion Criteria: * Patient is pregnant. * Patients with a positive result for any of the following diagnostic tests: Hep B Ag, Hep B Core Ab, Hep C Ab, HIV-1 Ab, HIV-2 Ab, HTLV-1 Ab, HTLV-2 Ab, RPR. * Patient has a history of autoimmune disease, specifically inflammatory bowel disease, systemic lupus erythematosis, or rheumatoid arthritis. * Patient is receiving concurrent systemic steroid therapy. * Patient has a known systemic hypersensitivity to DAC, Hiltonol, or any vaccine component.