• To evaluate and compare-
  
• the safety (absence of grade 3-4 toxicity) and efficacy (absence of proven and probable fungal infection) of liposomal amphotericin B given three times per week
  
• versus liposomal amphotericin B given once per week, versus oral vori.
  

• To determine-
  
• time to failure of prophylaxis
  
• frequency and time to empiric antifungal therapy
  
• number of patients with positive galactomannan index
  
• and, duration of positive antigenemia.
  

Ambisome and voriconazole are drugs that have been used to fight fungal infections, which typically occur during chemotherapy as a result of lowered immune system functioning. Ambisome works by binding to the sterol component of the fungal cell membrane. This causes "holes" to appear in the membrane, which leads to death of the fungal cell. Voriconazole inhibits an essential step of the biosynthesis of an important component of the fungal cell wall (ergosterol). This causes the impairment of the fungal cell wall.

Before you can start treatment on this study, you will have "screening tests." These tests will help the doctor decide if you are eligible to take part in this study. You will be asked questions about your medical history. You will have a complete physical exam and a chest x-ray. You will have computed tomography (CT) scans of the chest. You will also have about 1 teaspoon of blood drawn for routine tests. Test results from the pregnancy test that you will have before your leukemia treatment will be looked at for this study. You will not have a pregnancy test performed for this study.

If you are found to be eligible to take part in this study, you will be randomly assigned (as in the roll of dice) to one of 3 treatment groups (Group 1, Group 2, or Group 3). Participants in Groups 1 and 2 will receive treatment with ambisome. Participants in Group 3 will receive treatment with voriconazole. Participants in all 3 groups will begin treatment 24 hours after the last dose of chemotherapy.

If you are assigned to Group 1, you will receive ambisome by vein as a continuous infusion over 2 hours 1 time per day, 3 times each week.

If you are assigned to Group 2, you will receive ambisome by vein as a continuous infusion over 2 hours 1 time per week.

If you are assigned to Group 3, you will take 2 pills by mouth (1 hour after breakfast) and 2 pills by mouth (1 hour after dinner) for 1 day, which amounts to 4 pills in total on Day 1. You will then take 1 pill by mouth (1 hour after breakfast) and 1 pill by mouth (1 hour after dinner) everyday for the remainder of this study, which amounts to 2 pills in total each day.

You will have about 1 teaspoon of blood drawn for routine tests 2 times each week. You will also receive treatment with standard of care medications. These medications (which will be specified by your doctor) will be used to help decrease the risk of developing bacterial infections and viral infections.

If you develop a fever during treatment on this study, you will have a chest x-ray and a CT scan of the chest within 3 days after the fever started.

You may remain on this study for up to 35 days (if you are receiving chemotherapy for the first time) and up to 42 days (if you have had prior chemotherapy). Your participation may end on this study if your study doctor thinks it is necessary, if other antifungal therapy is required, or if you develop any intolerable side effects.