Eligibility

Inclusion Criteria:

Disease Status

- AML Induction Failure

- AML in 1st, 2nd, or 3rd Relapse (>10% bone marrow blasts)

- AML greater than or equal to 3rd CR

- MDS with >6% bone marrow blasts at diagnosis

- Secondary MDS with less than or equal to 5% bone marrow myeloblasts at diagnosis

- JMML with >6% bone marrow myeloblasts at diagnosis

Disease Immunophenotype Patients (AML only) receiving gemtuzumab ozogamicin must express
minimum of >10% or =10% CD33 positivity. Patients with <10% CD33 positivity will not
receive gemtuzumab ozogamicin.

Organ Function

Patients must have adequate organ function as defined below:

- Adequate renal function defined as:

- Serum creatinine <1.5 x normal, or

- Creatinine clearance or radioisotope GFR 40 ml/min/m2 or >60 ml/min/1.73 m2 or an
equivalent GFR as determined by the institutional normal range

- Adequate liver function defined as:

- Total bilirubin 1.5 x normal, or SGOT (AST) or SGPT (ALT) <2.0 x normal or =2.0 x
normal

- Adequate cardiac function defined as:

- Shortening fraction of >27% by echocardiogram, or

- Ejection fraction of >47% by radionuclide angiogram or echocardiogram

- Adequate pulmonary function defined as:

- DLCO >55% or =55% by PFT

- For children who are uncooperative, no evidence of dyspnea at rest, no exercise
intolerance, and a pulse oximetry >94% on room air

Exclusion Criteria:

- Patients with active CNS AML/JMML/MDS disease at time of conditioning therapy

- Female patients who are pregnant (positive HCG)

- Karnofsky <50% or Lansky <50% if 10 years or less

- Age >65 years

- Has received gemtuzumab in the previous 30 days or has not recovered from prior
gemtuzumab therapy.