Fludarabine and Cyclophosphamide With or Without Oblimersen in Treating Patients With Relapsed or Refractory Chronic Lymphocytic Leukemia

DISEASE CHARACTERISTICS: * Diagnosis of relapsed or refractory chronic lymphocytic leukemia (CLL) requiring therapy * Primary resistance, defined as disease progression without response during at least 2 courses of myelosuppressive therapy OR * Relapsed disease, defined as a response (remission or plateau) followed by relapse on or off prior therapy * At least 1 prior regimen must have contained fludarabine * Intermediate or high-risk CLL * Intermediate-risk disease must satisfy at least 1 of the following criteria for active disease: * Massive or progressive splenomegaly and/or lymphadenopathy * Spleen tip greater than 6 cm below costal margin * More than 10% weight loss within the past 6 months * Grade 2 or 3 fatigue * Fevers greater than 100.5 degrees F or night sweats for more than 2 weeks without evidence of infection * Progressive lymphocytosis with an increase of more than 50% over a 2-month period or an anticipated doubling time of less than 6 months * Worsening anemia or thrombocytopenia * Measurable disease with all of the following: * Absolute lymphocytosis greater than 5,000/mm\^3 * Lymphocytosis of small to moderate-size lymphocytes with less than 55% prolymphocytes, atypical lymphocytes, or lymphoblasts morphologically determined by manual differential * Bone marrow aspirate smear with at least 30% nucleated cells that are lymphoid or a bone marrow core biopsy showing lymphoid infiltrates compatible with CLL * Normocellular or hypercellular bone marrow * Lymphocyte immunophenotype that shows a predominant B-cell monoclonal population * No Rai stage 0 CLL or stable CLL not requiring therapy * No secondary leukemia or history of antecedent hematologic disorder prior to initial onset of CLL (e.g., myelodysplasia) PATIENT CHARACTERISTICS: Age: * Over 18 Performance status: * ECOG 0-2 Life expectancy: * Not specified Hematopoietic: * See Disease Characteristics * Platelet count at least 50,000/mm\^3 (hematopoietic growth factor or transfusion independent) * Negative Coombs' test * No bleeding or coagulation disorder * No history of hemolytic anemia, including autoimmune hemolytic anemia * No history of autoimmune thrombocytopenia Hepatic: * Albumin at least 3.0 g/dL * Bilirubin no greater than 2 mg/dL * AST no greater than 1.5 times upper limit of normal (ULN) (5 times ULN if due to CLL) * PT no greater than 1.5 times ULN OR * INR no greater than 1.3 * PTT no greater than 1.5 times ULN * No chronic hepatitis or cirrhosis Renal: * Creatinine no greater than 2.0 mg/dL Cardiovascular: * No uncontrolled congestive heart failure * No active symptoms of coronary artery disease (i.e., uncontrolled arrhythmia or recurrent chest pain despite prophylactic medication) * No New York Heart Association class III or IV disease * No cardiovascular signs or symptoms grade 2 or greater Other: * Able to maintain an ambulatory infusion pump * HIV negative * No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix * No known hypersensitivity to phosphorothioate-containing oligonucleotides, fludarabine, or cyclophosphamide * No concurrent medical disease that would preclude study participation * No uncontrolled seizure disorder * No unresolved serious infection * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: * No prior autologous or allogeneic stem cell transplantation * At least 3 weeks since prior immunologic therapy, cytokine therapy, vaccine therapy, or other biologic therapy for CLL and recovered * No concurrent interleukin-11 Chemotherapy: * See Disease Characteristics * At least 3 weeks since prior chemotherapy and recovered Endocrine therapy: * No concurrent corticosteroid therapy Radiotherapy: * At least 3 weeks since prior radiotherapy for CLL and recovered Surgery: * No prior organ allograft * At least 3 weeks since prior major surgery for CLL and recovered Other: * At least 3 weeks since other prior therapy for CLL and recovered * No other concurrent investigational therapy * No concurrent therapeutic anticoagulation * No concurrent immunosuppressive drugs