Pentostatin, Cyclophosphamide, and Rituximab With or Without Bevacizumab in Treating Patients With B-Cell Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma

Inclusion criteria

DISEASE CHARACTERISTICS: * Diagnosis of 1 of the following: * Biopsy proven small lymphocytic lymphoma (SLL) * Chronic lymphocytic leukemia (CLL)\* as evidenced by the following criteria: * Peripheral blood lymphocyte count \> 5,000/mm³ consisting of small to moderate size lymphocytes * Immunophenotyping consistent with CLL, defined by the following: * The predominant population of lymphocytes share both B-cell antigens (CD19, CD20, or CD23) as well as CD-5 in the absence of other pan-T-cell markers (CD-3 or CD-2) * Dim surface immunoglobulin expression * Exclusively kappa and lambda light chains * Negative FISH analysis for t(11;14)(IgH/CCND1) on peripheral blood or tissue biopsy samples NOTE: \*Splenomegaly, hepatomegaly, or lymphadenopathy are not required for the diagnosis of CLL * Has ≥ 1 of the following indications\*\* for chemotherapy: * Evidence of progressive marrow failure as manifested by the development of or worsening anemia (hemoglobin ≤ 11 g/dL) and/or thrombocytopenia (platelet count ≤ 100,000/mm³) * Symptomatic or progressive lymphadenopathy, splenomegaly or hepatomegaly * Has ≥ 1 of the following disease-related symptoms: * Weight loss \> 10% within the past 6 months * Extreme fatigue attributed to CLL * Fevers \> 100.5\^oF for 2 weeks without evidence of infection * Night sweats without evidence of infection * Progressive lymphocytosis (not due to the effects of corticosteroids) with an increase of \> 50% over a 2-month period or an anticipated doubling time of \< 6 months NOTE: \*\*Marked hypogammaglobulinemia or the development of a monoclonal protein in the absence of any of the above criteria for active disease are not sufficient indications for study treatment PATIENT CHARACTERISTICS: * Eastern Cooperative Oncology Group performance status 0-3 * Life expectancy ≥ 12 months * Total bilirubin ≤ 3.0 times upper limit of normal (ULN) (unless due to Gilbert's disease) * Direct bilirubin \< 1.5 mg/dL (in patients with Gilbert's disease) * Serum glutamate oxaloacetate transaminase ≤ 3.0 times ULN (unless due to hepatic involvement by CLL) * Creatinine ≤ 1.5 times ULN * Urine protein:creatinine ratio \< 1.0 OR \< 1 g of protein by 24-hour urine collection * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception during and for 12 months after completion of study treatment * Willing to provide mandatory blood and tissue samples * None of the following cardiovascular conditions: * NYHA class III-IV heart disease * Myocardial infarction within the past 6 months * Unstable angina * Stroke, cerebrovascular accident, or transient ischemic attack within the past 6 months * Arterial thromboembolic events within the past 12 months * Clinically significant peripheral vascular disease * Uncontrolled hypertension, defined as systolic BP \> 150 mm Hg or diastolic BP \> 100 mm Hg * Hypertension allowed provided it is controlled with a stable anti-hypertensive regimen * History of hypertensive crises or hypertensive encephalopathy * Deep venous thromboses or pulmonary embolism within the past 12 months * No evidence of bleeding diathesis or coagulopathy * No uncontrolled or active hemolytic anemia requiring immunosuppressive therapy or other pharmacologic treatment * No active or recent history (within the past 30 days) of hemoptysis (≥ ½ teaspoon of bright red blood per episode) * No abdominal fistula, gastrointestinal perforation, or intra-abdominal abscess within the past 6 months * No active peptic ulcer disease * No serious non-healing wound, ulcer, or bone fracture * No significant traumatic injury within the past 28 days * No uncontrolled infection * No active HIV infection * No other active primary malignancy (except nonmelanoma skin cancer or carcinoma in situ of the cervix) requiring treatment or limiting survival to ≤ 2 years * No psychiatric or addictive disorders or other conditions that, in the opinion of the investigator, would preclude study participation PRIOR CONCURRENT THERAPY: * Prior corticosteroids allowed * More than 4 weeks since prior radiotherapy * More than 28 days since prior and no concurrent major surgical procedure or open biopsy * More than 7 days since prior minor surgical procedure, fine needle aspiration, or core biopsy (other than bone marrow biopsy) * No concurrent therapeutic doses of coumadin-derivative anticoagulants (e.g., warfarin) * Doses of ≤ 2 mg daily allowed for prophylaxis of thrombosis * Prophylactic doses of low molecular weight heparin allowed * No other concurrent investigational agents for treatment of CLL or SLL * No other concurrent specific anticancer treatment except hormonal therapy