The goal of this clinical research study is to learn if the combination of fludarabine and cytarabine can help to control Acute Myelogenous Leukemia (AML), High-Risk Myelodysplastic Syndrome (MDS) or Chronic Myeloid Leukemia (CML) in myeloid blast crisis. The safety of this drug combination will also be studied.

The Study Drugs Fludarabine is designed to make cancer cells less able to repair damaged DNA (the genetic material of cells). This may increase the likelihood of the cells dying.

Cytarabine is designed to insert itself into DNA and stop the DNA from repairing itself.

Study Drug Administration:

If you are found to be eligible to take part in this study, you will receive fludarabine and cytarabine.

During each cycle (about 4-6 weeks), you will receive the study drugs for up to 5 days and you will be watched by the study staff for about 1 month.

Induction (Cycle 1):

For 3, 4, or 5 days during Days 1-5 of Cycle 1, you will receive fludarabine by vein over 15-30 minutes 2 times a day (about every 12 hours).

For 3, 4, or 5 days during Days 1-5 of Cycle 1, you will receive cytarabine by vein over about 2 hours 2 times a day (about every 12 hours).

If the cancer does not completely respond after Cycle 1, you may repeat induction (Cycle 1).

If the cancer completely responds, you will begin the consolidation cycles.

Consolidation (Cycles 2-7):

For 3 or 4 days during Days 1-4 of Cycles 2-7, you will receive fludarabine by vein over 15-30 minutes 2 times a day (about every 12 hours).

For 3 or 4 days during Days 1-4 of Cycles 2-7, you will receive cytarabine by vein over about 2 hours 2 times a day (about every 12 hours).

Study Visits:

At each study visit, you will be asked about any side effects you may be having and about any other drugs you may be taking.

During Induction Therapy (Cycle 1):

• Blood (about 2 tablespoons) will be drawn for routine tests every 3-7 days.
• About Day 28, you may have a bone marrow aspirate to check the status of the disease.

During Consolidation Therapy (Cycles 2-7):

• Blood (about 2 tablespoons) will be drawn for routine tests every 1-2 weeks.
• You will have a bone marrow aspirate every 2-3 cycles to check the status of the disease.

Length of Study:

You will be able to receive the study drugs for up to about 8 months. You will be taken off study treatment if you have intolerable side effects, if the disease gets worse, or if the study doctor thinks it is in your best interest.

Long-Term Follow-Up:

Every 3 months for 2 years after you are off study treatment, you will be called and asked how you are feeling, about any side effects you may be having, and about another other drugs you may be taking.

Supportive Care:

Please talk with your doctor about drugs that you can or cannot take while you are on study.

This is an investigational study. Cytarabine is FDA approved and commercially available as a frontline (first) treatment for AML. Fludarabine is FDA approved and commercially available for the treatment of CLL.

The combination of these 2 drugs to treat AML, MDS, or CML in myeloid blast crisis is investigational.

Up to 150 patients will take part in this study. All will be enrolled at M. D. Anderson.

Inclusion Criteria:

1. Sign an Internal Review Board (IRB)-approved informed consent document.
2. Age >/= 12 years.
3. Diagnosis of AML [other than acute promyelocytic leukemia (APL)] with refractory/relapsed disease. Patients with newly diagnosed AML will be eligible if not a candidate for intensive chemotherapy. Patients with high-risk (intermediate-2 or high by IPSS or >/=10% blasts) MDS will also be eligible. Patients with chronic myeloid leukemia (CML) in blast crisis will be eligible as well.
4. Eastern Cooperative Oncology Group (ECOG) performance status of \

Two years, ten months.

Of the 151 participants registered, four did not recieve treatment and were excluded from adverse event reporting.