Cyclophosphamide, Alvocidib, and Rituximab in Treating Patients With High Risk B-Cell Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma

Inclusion Criteria:

* Histologically confirmed chronic lymphocytic leukemia (CLL) or B-cell prolymphocytic leukemia\* (PLL) arising from CLL

  * Patients must have documented B-cell lymphocytosis \> 5 x 10\^9/L at some point since initial diagnosis of CLL
  * Patients must have B-cells that co-express CD5 with CD19 or CD20
  * Patients who do not have dim sIg or CD23 expression on their leukemia cells should be examined for cyclin D1 over-expression or t(11;14) to rule out mantle cell lymphoma
* To be considered high risk, patients must meet the following criteria:

  * At least 1 of the following:

    * 17p deletion
    * 11q deletion
    * Un-mutated IgV\_H (≥ 98% homology)
    * Age \> 70 years
    * B\_2M \> 4
  * AND at least 1 of the following:

    * Progressive or marked splenomegaly and/or lymphadenopathy
    * Anemia (hemoglobin \< 11 g/dL) or thrombocytopenia (platelets \< 100,000/mm\^3)
    * Weight loss exceeding 10% of body weight over preceding 6 months
    * NCI grade 2 or 3 fatigue
    * Fevers \> 100.5° F or night sweats for \> 2 weeks without evidence of infection
    * Progressive lymphocytosis, with an increase exceeding 50% over a 2-month period or a doubling time of \< 6 months
* No other concurrent hormones, chemotherapy, or radiotherapy except for steroids for new adrenal failure or hormones for nondisease-related conditions (e.g., insulin for diabetes)

  * No requirement for chronic corticosteroids
* ECOG performance status 0-2
* Creatinine ≤ 2.0 mg/dL
* Bilirubin ≤ 1.5 times normal unless due to Gilbert disease, hemolysis, or disease infiltration of the liver
* AST ≤ 2 times normal unless due to hemolysis or disease infiltration of the liver
* Negative pregnancy test
* Not pregnant or nursing
* Fertile patients must use effective contraception
* No secondary or other malignancy that will limit survival to \< 2 years
* No uncontrolled concurrent illness including, but not limited to, any of the following:

  * Ongoing or active infection
  * Symptomatic congestive heart failure
  * Unstable angina pectoris
  * Cardiac arrhythmia
  * Psychiatric illness or social situations that would limit compliance with study requirements
* No uncompensated HIV without adequate CD4 (\> 200/mm\^3) and requiring HIV medication
* No active hepatitis B infection
* No known G6PD deficiency
* No history of allergic reactions attributed to compounds of similar chemical or biologic composition to alvocidib, cyclophosphamide, rituximab, or other agents used in this study
* No prior alvocidib
* No prior purine analog therapy
* No more than 1 prior treatment with a biologic or alkylating agent
* No other concurrent investigational agents