The Study Drugs:

      Sapacitabine and cyclophosphamide are designed to damage the DNA (genetic material) of cancer
      cells, which may cause the cancer cells to die.

      Rituximab is designed to attach to cancer cells and damage them, which may cause the cancer
      cells to die. It is also designed to cause the immune system to attack cancer cells.

      Study Drug Administration:

      If you are found to be eligible to take part in this study, you will receive sapacitabine by
      mouth 1 time a day on Days 1-3 of each 28-day cycle. Try to take sapacitabine at least 1 hour
      before or 2 hours after a meal. On Days 1-3 of each cycle, you will also receive
      cyclophosphamide by vein over 30 minutes, starting 2 hours after you take sapacitabine.

      On Day 3 of Cycle 1 and Day 1 of Cycles 2 and beyond, you will receive rituximab by vein over
      6-8 hours.

      If side effects occur, the study doctor may decide to lower your study drug doses. If you
      have side effects during a dose, the study staff will check you for any other problems for 2
      hours after the dose.

      Other Drugs:

      On Days 1-14 of Cycle 1, you will take allopurinol by mouth 1 time a day to lower the risk of
      kidney damage.

      Before each dose of cyclophosphamide, you will receive Zofran (ondansetron) by vein over a
      few seconds to lower the risk of nausea.

      About 30-60 minutes before each dose of rituximab, you will take Tylenol (acetaminophen) and
      Benadryl (diphenhydramine hydrochloride) by mouth to lower the risk of side effects such as
      fever and chills.

      Study Visits:

      On Day 1 of each cycle:

        -  Blood (about 1-2 tablespoons) will be drawn for routine tests.

        -  You will also have a physical exam, including measurement of your vital signs, except
           Cycle 1.

        -  You will be asked about any side effects you may have had.

      On Days 8 and 22 of Cycle 1, and on Day 15 of every cycle:

        -  Blood (about 1-2 tablespoons) will be drawn for routine tests.

        -  You will be asked about any side effects you may have had.

      If your disease has had a good response and the doctor thinks it is needed to check the
      status of the disease, you will have a bone marrow aspiration and biopsy and a CT scan of the
      chest, abdomen and pelvis prior to Cycle 4 and possibly every other cycle after that (Cycles
      6, 8, 10, and so on).

      Length of Study:

      Once your doctor thinks the disease has had its best response, you may receive 2 more cycles
      of study therapy after that. You will no longer be able to receive the study drugs if the
      disease gets worse or intolerable side effects occur.

      End-of-Treatment Visit:

      The following tests and procedures will be performed after your last cycle of study drugs:

        -  You will have a physical exam, including measurement of your vital signs.

        -  Blood (about 2 tablespoons) will be drawn for routine tests.

      Follow-Up Visits:

      At 2 and 6 months and 1 and 2 years after your last dose of study drugs:

        -  You will be asked about any side effects you may have had and any drugs you may be
           taking.

        -  You will have a physical exam, including measurement of your vital signs.

        -  Blood (about 1 tablespoon) will be drawn for routine tests.

        -  If the doctor thinks the disease has completely responded, you will have a CT scan of
           the neck, chest, abdomen, and pelvis to confirm the response. You will also have a bone
           marrow aspiration and biopsy to confirm the response.

      At 3 years after your last dose of study drugs and 1 time a year from then on:

        -  You will be asked about any side effects you may have had and any drugs you may be
           taking.

        -  You will have a physical exam, including measurement of your vital signs.

        -  Blood (about 1 tablespoon) will be drawn for routine tests.

        -  You will have a bone marrow aspiration and biopsy if the doctor decides it is needed to
           check the status of the disease.

      If the doctor thinks it is needed anytime during follow-up, you will have a CT scan of the
      neck, chest, abdomen, and pelvis to check the status of the disease.

      Starting at Year 3, the follow-up tests and procedures can be done by your local doctor if
      that is more convenient to you. The test results should be sent to MD Anderson.

      You should tell your study doctor or staff if you start another cancer treatment during
      follow-up. If that occurs, your follow-up in this study will stop.

      This is an investigational study. Sapacitabine is not FDA approved or commercially available.
      It is currently being used for research purposes only. Cyclophosphamide and rituximab are FDA
      approved and commercially available to treat CLL and SLL. The combination of sapacitabine,
      cyclophosphamide, and rituximab is investigational.

      Up to 40 patients will take part in this study. All will be enrolled at MD Anderson.