Clofarabine in Treating Patients With T-Cell or Natural Killer-Cell Non-Hodgkin's Lymphoma That Has Relapsed or Not Responded to Previous Treatment

DISEASE CHARACTERISTICS: * Histologically confirmed T-cell or natural killer (NK)-cell lymphoma, including any of the following subtypes: * Blastic NK-cell lymphoma * T/NK-cell lymphoma/leukemia * Adult T-cell lymphoma/leukemia * T-cell prolymphocytic leukemia * T-lymphoblastic lymphoma * Peripheral T-cell lymphoma, not otherwise specified * Angioimmunoblastic T-cell lymphoma * Anaplastic large cell lymphoma * Transformed mycosis fungoides * Subcutaneous panniculitis-like T-cell lymphoma * Nasal T/NK-cell lymphoma * Enteropathy-type T-cell lymphoma * Hepatosplenic gamma/delta T-cell lymphoma * Relapsed or refractory disease, meeting both of the following criteria: * Must have been treated with prior cytotoxic chemotherapy and/or monoclonal antibody therapy * No standard curative treatment exists * Allogeneic bone marrow transplantation is not considered standard curative treatment * Evaluable disease (Phase I) * Measurable disease, defined as any nodal site or mass lesion ≥ 1.5 cm in longest transverse diameter on physical exam or CT scan OR a measurable extranodal site \> 1 cm (Phase II) * Patients with evaluable blood- or marrow-based disease are eligible PATIENT CHARACTERISTICS: * ECOG performance status 0-2 * Absolute neutrophil count ≥ 1,500/mm³ (Phase I) * Absolute neutrophil count ≥ 500/mm³ (Phase II) * Platelet count ≥ 100,000/mm³ (Phase I) * Platelet count ≥ 50,000/mm³ (Phase II) * Creatinine \< 2.0 mg/dL\* * Bilirubin ≤ 2.0 times upper limit of normal (ULN)\* * AST and ALT ≤ 2.5 times ULN\* * No active infection requiring antibiotics * No New York Heart Association class III or IV congestive heart failure * No known HIV positivity * No other active malignancy requiring therapy * No other serious or life-threatening condition deemed unacceptable by the principal investigator * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception NOTE: \*Unless due to lymphoma and patients are entering to the phase II portion of the study PRIOR CONCURRENT THERAPY: * See Disease Characteristics * At least 3 weeks since prior therapy, including any of the following: * Interferon * Antibody therapy * Retinoids * Other non-chemotherapeutic treatment * Concurrent stable-dose corticosteroids allowed * No colony-stimulating factor therapy during the first course of study therapy