Decitabine, Doxorubicin, and Cyclophosphamide in Treating Children With Relapsed or Refractory Solid Tumors or Neuroblastoma

Inclusion Criteria:

* Histologically confirmed diagnosis of either of the following:

  * Solid tumor (part A)

    * No lymphoma
  * Neuroblastoma (part B)

    * Original diagnosis may be based on elevated urine vanillylmandelic acid (VMA) and homovanillic acid (HVA) and bone marrow examination
    * Accessible disease by bone marrow aspirate or tumor biopsy

      * No laparotomy, thoracotomy, endoscopy, or craniotomy for biopsy
* No known curative therapy OR therapy proven to prolong survival with an acceptable quality of life available
* No known brain or spinal cord metastases
* No CNS tumors
* Performance status - Karnofsky 50-100% (patients 11 to 21 years of age)
* Performance status - Lansky 50-100% (patients ≤ 10 years of age)
* Parts A and B without bone marrow infiltration:

  * Absolute neutrophil count ≥ 1,000/mm\^3
  * Platelet count ≥ 100,000/mm\^3 (transfusion independent)
* Part B with bone marrow infiltration (i.e., tumor metastatic to bone marrow with granulocytopenia, anemia, and/or thrombocytopenia):

  * Absolute neutrophil count ≥ 750/mm\^3
  * Platelet count ≥ 50,000/mm\^3 (transfusion independent)
* Hemoglobin ≥ 8.0 g/dL (transfusion allowed)
* No sickle cell anemia
* Bilirubin ≤ 1.5 mg/dL
* ALT ≤ 5 times upper limit of normal
* No significant hepatic dysfunction that would compromise the tolerability of decitabine or interfere with study procedures or results
* Creatinine based on age as follows:

  * ≤ 0.8 mg/dL (5 years of age and under)
  * ≤ 1.0 mg/dL (6 to 10 years of age)
  * ≤ 1.2 mg/dL (11 to 15 years of age)
  * ≤ 1.5 mg/dL (16 to 21 years of age)
* Creatinine clearance or radioisotope glomerular filtration rate ≥ 70 mL/min
* No significant renal dysfunction that would compromise the tolerability of decitabine or interfere with study procedures or results
* Shortening fraction ≥ 28% by echocardiogram
* Ejection fraction of ≥ 45% by MUGA
* No significant pulmonary dysfunction that would compromise the tolerability of decitabine or interfere with study procedures or results
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception
* No prior allergic reaction attributed to compounds of similar chemical or biological composition to agents used in this study
* No uncontrolled serious infection
* No significant end-organ dysfunction that would compromise the tolerability of decitabine or interfere with study procedures or results
* Recovered from prior immunotherapy
* At least 7 days since prior biologic therapy
* More than 1 week since prior growth factor therapy (2 weeks for pegfilgrastim)
* More than 2 weeks since prior epoetin alfa
* At least 6 months since prior autologous stem cell transplantation
* At least 6 months since prior allogeneic bone marrow transplantation

  * Patients must have full organ recovery and no evidence of graft-versus-host disease
* No concurrent immunomodulating agents
* No concurrent immunotherapy
* No concurrent biologic therapy
* No concurrent epoetin alfa
* Recovered from prior chemotherapy
* More than 2 weeks since prior myelosuppressive chemotherapy (6 weeks for nitrosoureas)
* Prior total lifetime cumulative anthracycline dose ≤ 450 mg/m\^2 of doxorubicin or equivalent
* No other concurrent chemotherapy
* No concurrent hydroxyurea
* Recovered from prior radiotherapy
* More than 2 weeks since prior local palliative small port radiotherapy
* More than 6 months since prior substantial bone marrow irradiation (e.g., cranio-spinal irradiation, total body irradiation, or hemi-pelvic irradiation)
* No concurrent radiotherapy
* No other concurrent anticancer therapy
* No other concurrent investigational agents
* Concurrent oral iron supplementation for patients with a known iron deficiency or a microcytic hypochromic anemia allowed