This treatment study for relapsed high-risk neuroblastoma, Ewings sarcoma, osteogenic sarcoma, rhabdomyosarcoma or synovial sarcoma involves an autologous cancer testis (CT) antigen specific dendritic cell (DC) vaccine preceded by decitabine as a demethylating chemotherapy.

For vaccine production, mature DC will be pulsed with overlapping peptides mixes derived from full-length NY-ESO-1, MAGE-A1, and MAGE-A3.

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.