Ondansetron Versus Aprepitant Plus Ondansetron for Emesis

Cytarabine is a drug that is used to treat AML and HR-MDS. It is known to cause nausea
and/or vomiting. All patients that receive cytarabine also receive drugs to help prevent
these side effects.

The Study Drugs:

Ondansetron is designed to block the action of serotonin, a substance in the brain that
causes chemotherapy-related nausea and vomiting.

Aprepitant is designed to block a different natural substance in the brain that causes
chemotherapy-related nausea and vomiting.

Study Groups:

If you are found eligible to take part in this study, you will be randomly assigned (as in
the flip of a coin) to 1 of 2 groups. You will have an equal chance of being in either
group.

If you are in Group 1, you will receive ondansetron.

If you are in Group 2, you will receive ondansetron and aprepitant.

Study Drug Administration:

Both groups will receive ondansetron by vein from 30 minutes before receiving chemotherapy
until 6 to12 hours after chemotherapy. The length of the chemotherapy infusion will be
different for all patients.

If you are in Group 2, in addition to ondansetron, you will take 1 capsule of aprepitant
every morning while receiving chemotherapy. You will take your last dose of aprepitant the
day after your chemotherapy infusion is completed. If you miss a dose of aprepitant, you can
take it as soon as you remember.

Study Diary:

You will fill out a study diary every day for the 7 days after the chemotherapy. You will
record how often you experience nausea and/or vomiting and any time you need other
medications during this study. It should take about 5 minutes to complete each time.

Length of Study:

You will be on study for up to 7 days. You will be taken off study if intolerable side
effects occur.

Blood Draws:

Blood (about 1 teaspoon) will be drawn for routine tests after your last dose (+/- 3 days)
of study drug.

This is an investigational study. Ondansetron and aprepitant are both FDA approved and
commercially available for the prevention of chemotherapy-related nausea and vomiting. Using
the drugs in combination is investigational.

Up to 100 participants will take part in this study. All will be enrolled at MD Anderson.

Inclusion Criteria:

1. Patients greater than or equal to 18 years of age.

2. Patients with a diagnosis of acute myelogenous leukemia, high-risk myelodysplastic
syndrome, chronic myelogenous leukemia in blast crisis or acute undifferentiated
leukemia who will receive chemotherapy with regimens containing high-dose cytarabine
(greater or equal 1g/m^2/d for at least 3 days).

3. Patients must sign an informed consent indicating they are aware of the
investigational nature of this study, in keeping with the policies of the hospital.

Exclusion Criteria:

1. Patients with emesis or grade 2 or 3 nausea present less than or equal to 24 hours
before chemotherapy.

2. Patients with ongoing emesis due to any organic etiology

3. Patients with known hypersensitivity to the study drug or to 5-HT3 receptor
antagonists

4. Patients receiving pimozide, terfenadine, astemizole, or cisapride