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