506U78 in Treating Patients With Refractory or Relapsed Acute Lymphoblastic Leukemia or Lymphoblastic Lymphoma

DISEASE CHARACTERISTICS: * Histologically confirmed diagnosis of T-cell acute lymphoblastic leukemia (ALL) or lymphoblastic lymphoma (LBL) * Leukemia or lymphoma cells should express at least two of the following cell surface antigens: CD1a, CD2, CD3 (surface or cytoplasmic), CD4, CD5, CD7, and CD8 * Leukemia cells should be negative for myeloperoxidase or Sudan Black B If the only T cell markers present are CD4 and CD7, the leukemic cells should be demonstrated to lack the myeloid markers CD33 and/or CD13 * Refractory to at least one induction treatment regimen or in first or later relapse after achieving a complete remission * No CNS leukemia or lymphoma requiring intrathecal or craniospinal radiotherapy PATIENT CHARACTERISTICS: * Age: 16 and over * Bilirubin no greater than 2 times upper limit of normal (unless due to leukemia) * Creatinine clearance at least 50 mL/min (unless due to leukemia) * No neurologic toxicity of grade 3 or greater during prior treatment of ALL/LBL * No preexisting neuropathy of grade 2 or greater regardless of causality * No history of seizure disorder * Not pregnant or nursing * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: * No concurrent erythropoietin * No other concurrent chemotherapy * No concurrent dexamethasone or other steroidal antiemetics * No concurrent hormone therapy, except for non-disease-related conditions