Arsenic Trioxide in Treating Patients With Relapsed or Refractory Acute Lymphoblastic Leukemia

DISEASE CHARACTERISTICS: * Morphologically proven acute lymphoblastic leukemia (ALL) * Subtypes L1, L2, or L3 * Bone marrow morphology with greater than 25% lymphoblasts * ALL morphology and cytochemistry with myeloid markers eligible * Refractory to induction therapy or relapsed following chemotherapy or autologous blood or bone marrow transplantation * Any number of prior relapses allowed * No relapse following allogeneic transplantation * Prior CNS leukemia allowed if treated and currently disease-free PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * ECOG 0-2 Life expectancy: * At least 6 months Hematopoietic: * Not specified Hepatic: * Bilirubin no greater than 2.0 mg/dL * SGOT/SGPT no greater than 2 times upper limit of normal (ULN) * Alkaline phosphatase no greater than 2 times ULN Renal: * Creatinine no greater than 2 mg/dL Other: * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No significant active infection * No other medical conditions that would likely decrease life expectancy * No other prior malignancy within the past 5 years except cured basal or squamous cell skin cancer or carcinoma in situ of the cervix PRIOR CONCURRENT THERAPY: Biologic therapy: * See Disease Characteristics Chemotherapy: * See Disease Characteristics Endocrine therapy: * At least 2 weeks since prior systemic corticosteroids Radiotherapy: * Not specified Surgery: * Not specified Other: * No concurrent antibiotics for active or resolving infection