Inclusion Criteria:

- All patients, 18 years of age or older, with a diagnosis of CML.

- Patients must have a life expectancy of at least 12 weeks.

- Patients must have an ECOG performance status of 0-2.

- Patients must sign an informed consent.

- Patients should have adequate hepatic function with a total bilirubin < 2 mg/dl and
SGOT or SGPT < two times the upper limit of normal, and adequate renal function as
defined by a serum creatinine < 1.5 x upper limit of normal.

- Patients with CML in chronic phase on imatinib as first line therapy who fulfill the
following criteria:

- The patient has at least two tests for quantitative reverse transcriptase polymerase
chain reaction (RT-PCR) for bcr-abl (peripheral blood or bone marrow aspirate). The
results of these tests should demonstrate a relative plateau in the effect of
imatinib on the detected level of the transcript (i.e. there should less than a ½ log
difference between the last two values). Note: Patients will be eligible if the more
recent study is greater than the previous study by any value.

- The last two quantitative RT-PCR studies should be at least 3 months apart.

- The patient should have received at least 9 months of imatinib since the diagnosis of
CML.

- The patient is tolerating imatinib without any grade 3 or greater toxicity.

Exclusion Criteria:

- Pregnant women or nursing mothers are not eligible for this trial. Patients of child
bearing potential must use adequate contraception.

- Patients may receive no other concurrent chemotherapy or radiation therapy during
this trial.

- Patients with severe medical problems such as uncontrolled diabetes mellitus or
cardiovascular disease or active infections are not eligible for this trial.

- Patients who have a hypersensitivity to valproic acid, derivatives, or any component
of the formulation. Patients with hepatic disease or significant impairment, or urea
cycle disorders