Talotrexin in Treating Young Patients With Recurrent Solid Tumors or Leukemia That is Recurrent or Does Not Respond to Treatment

DISEASE CHARACTERISTICS: * Diagnosis of either of the following: * Recurrent solid tumor * Histologically confirmed\* malignancy at original diagnosis or relapse * Measurable or evaluable disease * Lymphoma or primary CNS tumor allowed * Patients with CNS tumors must be on a stable or decreasing dose of dexamethasone for the past 7 days * Recurrent or refractory leukemia * Confirmed relapse, as defined by M3 marrow (25% blasts in bone marrow aspirate or biopsy) * Active extramedullary disease allowed provided there is no leptomeningeal involvement NOTE: \*Histological confirmation not required for intrinsic brain stem tumors * Bone marrow metastases allowed * Not refractory to red blood cell or platelet transfusion * No pleural effusion or significant ascites * No known curative therapy or therapy proven to prolong survival with an acceptable quality of life exists * No Down syndrome PATIENT CHARACTERISTICS: * Karnofsky performance status (PS) 50-100% (for patients \> 10 years of age) OR Lansky PS 50-100% (for patients ≤ 10 years of age) * Absolute neutrophil count ≥ 1,000/mm³ (for patients with solid tumors without bone marrow involvement) * Platelet count ≥ 100,000/mm³ (transfusion independent) * Hemoglobin ≥ 8.0 g/dL * Creatinine clearance or radioisotope glomerular filtration rate ≥ 70 mL/min OR creatinine adjusted according to age as follows: * No greater than 0.6 mg/dL (1 year to 23 months) * No greater than 0.8 mg/dL (2 to 5 years) * No greater than 1.0 mg/dL (6 to 9 years) * No greater than 1.2 mg/dL (10 to 12 years) * No greater than 1.4 mg/dL (13 years and over \[female\]) * No greater than 1.5 mg/dL (13 to 15 years \[male\]) * No greater than 1.7 mg/dL (16 years and over \[male\]) * Bilirubin ≤ 1.5 times upper limit of normal (ULN) * ALT ≤ 110 U/L (ULN is 45 U/L) * Albumin ≥ 2 g/dL * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No uncontrolled infection * No known condition that, in the opinion of the investigator, would preclude study compliance PRIOR CONCURRENT THERAPY: * Recovered from all prior treatment-related toxicity * At least 3 weeks since prior myelosuppressive chemotherapy (6 weeks for nitrosourea) (for patients with solid tumors) * At least 24 hours since prior cytoreduction therapy initiated with hydroxyurea (for patients with leukemia) * At least 2 weeks since prior local palliative radiotherapy (small port) * At least 6 months since prior total-body irradiation (TBI), craniospinal radiotherapy, or ≥ 50% radiotherapy to the pelvis * At least 6 weeks since prior substantial bone marrow radiotherapy * At least 3 months since prior stem cell transplant or rescue without TBI * No evidence of active graft-versus-host disease * At least 7 days since prior growth factor therapy * At least 7 days since prior biological therapy * No nonsteroidal anti-inflammatory drugs (NSAIDs), aspirin or other salicylates, penicillins, sulfa drugs (bactrim, septra), ciprofloxacin, tetracycline, thiazide diuretics, or probenecid within 2 days prior to, during, or within 5 days after treatment with talotrexin * No long-acting NSAIDs (e.g., nabumetone, naproxen, oxaprozin, piroxicam) within 5 days prior to, during, or within 5 days after treatment with talotrexin * No concurrent investigational drugs * No concurrent anticancer agents or therapy (e.g., chemotherapy, radiotherapy, immunotherapy, or biologic therapy)