Purpose : The main objective of this study is to assess the efficacy and tolerance of the addition of repeated doses of low doses (3mg/m2) of Gemtuzumab Ozogamicin (GO) in addition with standard doses of Ara-C in previously untreated patients aged 60 to 80 years with de novo acute myeloblastic leukemia (AML) and non adverse cytogenetics. The main end point for efficacy is 2 years-event free survival. The secondary efficacy endpoints are CR/Cri rates, cumulative incidence of relapse and overall survival. The secondary endpoints for safety are early death rate (before day 30 and 60), grade 3 to 5 adverse events and severe adverse events, cardiac toxicity and quality of life. Additional secondary endpoints are treatment by covariate interactions with respect to biological characteristics present at diagnosis (CD33 positivity, cytogenetic, molecular abnormalities) or after treatment (Minimal residual disease levels). This study is an exploratory study. Patients will be allocated at inclusion with a 2/1 ratio either to receive treatment with GO and cytarabine or Idarubicin and cytarabine in a 3+7 regimen similar to the "backbone" ALFA 1200 scheme used concurrently by the ALFA group as treatment of AML patients aged >60 years.

Primary objective. The primary objective is to assess the efficacy of two doses of Gemtuzumab ozogamicin (GO) during induction and one dose of GO during first consolidation in combination with Cytarabine in elderly patients with AML in the non adverse cytogenetics-risk group.

Inclusion Criteria:

• Patients with a morphologically proven diagnosis AML and both the following criteria:
• Age ≥ 60 years and < 80 years.
• Not previously treated for their disease.
• With favourable or intermediate-risk cytogenetics. (Patients with urgent clinical need to begin treatment might be included before cytogenetic results, when necessary if they do not respond to Hydroxyurea. Patients might be included if the cytogenetic results are not expected in a time limit < 5 days after AML diagnosis).
• Fit to receive intensive chemotherapy
• Cardiac function determined by radionucleide or echography within normal limits.
• Signed informed consent

Exclusion Criteria:

• M3-AML
• Presence of adverse cytogenetics (according to European LeukemiaNet recommendation.) (17) defined as one of the following abnormalities: -5/5q-, -7, t(6;9), t(v;11q23) excluding t(9;11), inv(3)(q21;q26.2) or t(3;3)(q21;q26.2), complex karyotype (3+ abnormalities)
• Secondary AML following treatment with radiotherapy or chemotherapy.
• AML following previously known myeloproliferative or myelodysplastic syndrome.
• ECOG performance status (PS) 0 to 3
• Serum creatinin level > or = 2.5N; AST and ALT level > or = 2.5N; total bilirubin level > or = 2N