Combination Chemotherapy With or Without Gemtuzumab in Treating Young Patients With Newly Diagnosed Acute Myeloid Leukemia

OBJECTIVES:

Primary

- Compare the event-free survival (EFS) and overall survival (OS) of young patients with
newly diagnosed acute myeloid leukemia (AML) treated with conventional combination
chemotherapy with vs without gemtuzumab ozogamicin (GMTZ).

Secondary

- Compare the remission induction rates after two courses of therapy in these patients.

- Compare disease-free survival and OS in patients who are eligible for an human
leukocyte antigen (HLA)-matched family donor (MFD) stem cell transplant (SCT) by virtue
of their risk classification, with patients assigned to MFD SCT if a MFD is available,
or to chemotherapy if a MFD is not available.

- Determine the outcome of patients with Down syndrome who are 4 years of age or older at
diagnosis and treated with conventional combination chemotherapy without GMTZ.

- Compare the EFS and OS of patients with de novo AML treated with conventional
combination chemotherapy with vs without GMTZ censoring MFD SCT recipients.

- Determine the prevalence and prognostic significance of molecular abnormalities of KIT,
CCAAT-enhancer binding protein alpha (CEBPα) and MLL-Partial tandem duplications (PTD)
genes in these patients.

- Determine the leukemic involvement of hematopoietic early progenitor and its role in
defining response to therapy.

- Assess the ability of a second-generation flow cytometric assay to predict patients at
high risk for relapse during periods of clinical remission.

- Examine whether GMTZ significantly improves EFS and OS in patients with higher CD33
concentrations/intensity.

- Examine whether GMTZ significantly improves complete remission, EFS, and OS in each of
the cytogenetic risk groups (high-, intermediate-, and low-risk) identified in prior
Medical Research Council trials.

- Utilize fluorescence in situ hybridization (FISH) analysis to identify variant patterns
among subgroups of patients who demonstrate the same G-banded chromosomal abnormality
(e.g., inv[16]/t[16;16], t[8;21], 11q23 abnormality) and determine whether these
variant patterns account for the heterogeneity of responses to therapy.

- Examine the impact of complex karyotypes (≥ 3, ≥ 4, and ≥ 5 abnormalities) on OS and
EFS in intermediate-risk patients for whom no high-risk or low-risk cytogenetic
abnormalities exist.

OUTLINE: This is a randomized, multicenter study. Patients are stratified according to
relapse risk (high vs intermediate vs low). Patients are randomized to 1 of 2 treatment
arms. Patients with Down syndrome are nonrandomly assigned to arm I (but do not undergo
allogeneic stem cell transplant [SCT]).

- Arm I (standard therapy):

- Induction 1: Patients receive cytarabine IT at the time of diagnosis or on day 1*.
Patients also receive cytarabine IV on days 1-10, daunorubicin hydrochloride IV
over 6 hours on days 1, 3, and 5, and etoposide IV over 4 hours on days 1-5. After
3 weeks of rest, all patients (regardless of remission status) proceed to
induction 2.

NOTE: *Patients with Central Nervous System (CNS) disease receive cytarabine IT twice weekly
until the cerebrospinal fluid is clear, followed by two additional IT treatments. Patients
with refractory CNS leukemia after 6 doses of IT treatment are removed from the study.

- Induction 2: Patients receive cytarabine IT on day 1, cytarabine IV on days 1-8,
daunorubicin hydrochloride IV over 6 hours on days 1, 3, and 5, and etoposide IV over 4
hours on days 1-5. After 3 weeks of rest, patients in complete remission (CR) proceed
to intensification 1. Patients with refractory disease are removed from protocol
therapy.

- Intensification 1: Patients receive cytarabine IT on day 1, high-dose cytarabine IV
over 1 hour on days 1-5, and etoposide IV over 1 hour on days 1-5. After 3 weeks of
rest, patients in remission proceed to intensification 2, followed by intensification
3. Patients in remission proceed to allogeneic SCT 2-8 weeks after blood counts
recover. Patients with high-risk disease with an alternative donor proceed to
intensification 2 and 3, followed by allogeneic SCT. Patients not in remission are
removed from protocol therapy.

- Intensification 2: Patients receive cytarabine IT on day 1, high-dose cytarabine IV
over 2 hours on days 1-4, and mitoxantrone hydrochloride IV over 1 hour on days 3-6.
After 3 weeks of rest, patients proceed to intensification 3.

- Intensification 3: Patients receive high-dose cytarabine IV over 3 hours on days 1, 2,
8, and 9 and asparaginase intramuscularly on days 2 and 9.

- Arm II:

- Induction 1: Patients receive treatment as in induction 1 of arm I. Patients also
receive gemtuzumab ozogamicin (GMTZ) IV over 2 hours on day 6.

- Induction 2: Patients receive treatment as in induction 2 of arm I.

- Intensification 1: Patients receive treatment as in intensification 1 of arm I.

- Intensification 2: Patients receive treatment as in intensification 2 of arm I.
Patients also receive GMTZ IV over 2 hours on day 7.

- Intensification 3: Patients receive treatment as in intensification 3 of arm I.

- Allogeneic SCT (for patients with intermediate- or high-risk disease):

- MFD: Patients receive a conditioning regimen comprising busulfan IV over 2 hours every
6 hours on days -9 to -6 and cyclophosphamide IV over 1 hour on days -5 to -2. Patients
undergo allogeneic SCT on day 0. Patients receive cyclosporine IV or orally twice daily
on days -1 to 180 and methotrexate IV on days 1, 3, 6, and 11. Patients receive
graft-vs-host disease (GVHD) prophylaxis comprising cyclosporine IV over 1-4 hours or
orally twice daily on days -1 to 180 and methotrexate IV on days 1, 3, 6, and 11.

- Matched alternative donor: Patients receive a conditioning regimen comprising busulfan
and cyclophosphamide as above. Patients also receive antithymocyte globulin IV over 6-8
hours on days -3 to -1. Patients then undergo allogeneic SCT and receive GVHD
prophylaxis as above.

After completion of study treatment, patients are followed periodically for 3 years and then
annually thereafter.

PROJECTED ACCRUAL: A total of 1,012 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

- Newly diagnosed acute myeloid leukemia (AML)

- Meets customary criteria for AML with ≥ 20% bone marrow blasts (by WHO
classification)

- Patients with < 20% bone marrow blasts and cytopenia or myelodysplastic
syndromes (e.g., chronic myelomonocytic leukemia, refractory anemia (RA),
RA with excess blasts, RA with ringed sideroblasts) are eligible provided 1
of the following criteria is met:

- Karyotypic abnormality characteristic of de novo AML
(t[8;21][q22;q22], inv[16][p13q22], t[16;16][p13;q22], or 11q23
abnormalities)

- Unequivocal presence of megakaryoblasts (by WHO classification)

- Isolated myeloid sarcoma (i.e., myeloblastoma or chloroma) allowed regardless of
bone marrow results

- Infants < 1 month of age with progressive disease* are eligible NOTE: *Infants < 1
month of age with AML may be given supportive care until it is clear that the
leukemia is not regressing (i.e., the disappearance of peripheral blasts and the
normalization of peripheral blood counts)

- Patients with Down syndrome ≥ 4 years of age are eligible

- No juvenile myelomonocytic leukemia

- No Fanconi's anemia, Kostmann syndrome, Shwachman syndrome, or any other known bone
marrow failure syndrome

- No promyelocytic leukemia (M3)

- No secondary or treatment-related AML

- Matched family donor criteria (for patients with intermediate-risk or high-risk
disease):

- HLA-A, -B, -C, and beta chain (-DRB1), identical or 1 antigen or allele
mismatched by molecular high resolution technique

- All available first-degree family members (parents and siblings) must be HLA
typed

- No syngeneic donors

- Matched alternative donor criteria (for patients with high-risk disease):

- HLA-A, -B, -C, and -DRB1, identical or 1 antigen or allele mismatched donor

- HLA-A, -B, and -DRB1 4 of 6 antigen matched unrelated cord blood donor

- Mismatched family member donor with ≥ 1 haplotype match or 5 of 6 antigen
phenotypic match

PATIENT CHARACTERISTICS:

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

- No prior chemotherapy, radiation therapy, or any antileukemic therapy

- Topical or inhalation steroids for other conditions allowed

- Intrathecal cytarabine given at diagnosis allowed

- No other prior treatment for AML

- No concurrent peripheral blood stem cell transplantation in patients with matched
family donor