DISEASE CHARACTERISTICS:

• Histologically confirmed solid tumor (phase I, stratum A), neuroblastoma (phase II, stratum B), or relapsed/refractory acute lymphoblastic leukemia (ALL) (phase II, stratum C)

  • Relapsed or refractory disease

    • Patients with leukemia who relapse during standard maintenance therapy are eligible at time of relapse

• Meets the following criteria for measurable or evaluable disease as defined below by stratum:

  • Stratum A: measurable or evaluable disease

  • Stratum B: meets 1 of the following criteria:

    • Measurable tumor on MRI, CT scan, or x-ray obtained within 4 weeks prior to study entry
    • Evaluable tumor by MIBG scan or bone marrow involvement with tumor cells seen on routine morphology
  • Stratum C: must have M3 bone marrow
• No existing curative therapy for the disease or therapy proven to prolong survival with an acceptable quality of life
• No CNS tumors or known CNS metastatic disease

PATIENT CHARACTERISTICS:

• Karnofsky performance status (PS) 50-100% (patients > 16 years of age) OR Lansky PS 50-100% (patients ≤ 16 years of age)

• Patients with solid tumors (phase I, stratum A) must meet the following hematopoietic criteria:

  • ANC ≥ 1,000/μL
  • Platelet count ≥ 100,000/μL (no platelet transfusions within 7 days prior to enrollment)
  • Hemoglobin ≥ 8.0 g/dL (transfusion allowed)

• Patients in phase II portion of the study (stratum B & C) must meet the following hematopoietic criteria:

  • ANC ≥ 750/μL
  • Platelet count ≥ 50,000/μL (transfusion allowed)*
  • Hemoglobin ≥ 8.0 g/dL (transfusion allowed)* NOTE: * Patients with leukemia must not be refractory to red blood cell or platelet transfusions

• Creatinine clearance or radioisotope glomerular filtration rate ≥ 70ml/min OR serum creatinine based on age/gender (male [M], female [F]) as follows (in mg/dL):

  • 0.6(M), 0.6(F) (for patients 1 to < 2 years of age)
  • 0.8(M), 0.8(F) (for patients 2 to < 6 years of age)
  • 1(M), 1(F) (for patients 6 to < 10 years of age)
  • 1.2(M), 1.2(F) (for patients 10 to < 13 years of age)
  • 1.5(M), 1.4(F) for patients 13 to < 16 years of age)
  • 1.7(M), 1.4(F) (for patients 16 years of age and over)
• Bilirubin ≤ 1.5 times upper limit of normal for age
• ALT ≤ 110/µL
• Serum albumin ≥ 2 g/dL.
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• No uncontrolled infection
• Patients must be able to swallow capsules
• No patients who are unable to comply with the safety monitoring requirements of the study, in the opinion of the investigator

PRIOR CONCURRENT THERAPY:

• Recovered from prior chemotherapy, immunotherapy, or radiotherapy for patients who relapsed when not receiving standard ALL maintenance therapy
• More than 3 weeks since prior myelosuppressive chemotherapy (6 weeks for nitrosourea) (stratum A)
• At least 14 days since prior cytotoxic therapy
• At least 24 hours since cytoreduction with hydroxyurea
• At least 7 days since prior hematopoietic growth factor therapy
• At least 7 days since prior biological therapy (anti-neoplastic agent)
• At least 2 weeks since prior local palliative external radiotherapy (XRT) (small port)
• At least 6 weeks since prior treatment with therapeutic doses of iodine I 131 metaiodobenzylguanidine
• At least 6 months since prior total-body irradiation (TBI), craniospinal XRT, or radiation to more than 50% of pelvis
• At least 6 weeks since prior other substantial bone marrow radiation
• At least 3 months since prior stem cell transplant or rescue without TBI AND no evidence of active graft vs host disease
• More than 7 days since prior growth factors that support platelet or white cell number or function

• Concurrent corticosteroids allowed provided patient is on a stable or decreasing dose of corticosteroid for

  • 7 days prior to study enrollment
• No other concurrent investigational drug

• No other concurrent anticancer therapy, including chemotherapy, radiotherapy, immunotherapy, or biological therapy

  • Concurrent intrathecal methotrexate allowed for patients with ALL at the discretion of the treating investigator
• No concurrent chronic benzodiazepines