This is a randomized phase II, four-arm, open-label, multi-center study in adult patients with acute myeloid leukemia (AML) as defined in inclusion/exclusion criteria.

The primary efficacy objective is to evaluate the impact of sequential or concurrent addition of 5-azacytidine to intensive induction chemotherapy with idarubicin and etoposide on the complete remission (CR) rate

Sample size: 336 patients

The treatment duration of an individual patient randomized into one of the three experimental arms (Arm B, C, D) (in case of application of induction, consolidation and maintenance therapy with Azacitidine) is about 30 months.

The treatment duration for patients randomized into the standard arm of the study (Arm A) is about 7 months (in case of application of induction, consolidation and 2-yrs observation as maintenance (without treatment with Azacitidine)).

In case of induction followed by consolidation with allogeneic Stem cell transplantation (SCT) the treatment duration per patient is about 6 months.

Every patient will be followed until month 54 after inclusion into the study. Duration of the study for an individual patient including treatment (induction, consolidation [chemotherapy or allogeneic SCT], maintenance [experimental arm with Azacitidine or observation]) and follow-up period: 54 months

Inclusion Criteria:

• Patients with suspected diagnosis of acute myeloid leukemia or related precursor neoplasm, or acute leukemia of ambiguous lineage (classified according to the World Health Organization (WHO) classification)
• Patients considered eligible for intensive chemotherapy
• WHO performance status of ≤ 2
• Age ≥ 18 years. There is no upper age limit.
• No prior chemotherapy for leukemia except hydroxyurea to control hyperleukocytosis
• Non-pregnant and non-nursing. Women of childbearing potential (WOCBP) must have a negative serum or urine pregnancy test within a sensitivity of at least 25 mIU/mL within 72 hours prior to registration. "Women of childbearing potential" is defined as a sexually active mature woman who has not undergone a hysterectomy or who has had menses at any time in the preceding 24 consecutive months.
• Female patients in the reproductive age and male patients must agree to avoid getting pregnant or to father a child while on therapy and for 3 month after the last dose of chemotherapy.
• Women of child-bearing potential must either commit to continued abstinence from heterosexual intercourse or begin one acceptable method of birth control (IUD, tubal ligation, or partner's vasectomy). Hormonal contraception is an inadequate method of birth control.
• Men must use a latex condom during any sexual contact with women of childbearing potential, even if they have undergone a successful vasectomy. (while on therapy and for 3 month after the last dose of chemotherapy)
• Signed written informed consent.

Exclusion Criteria:

-AML with other recurrent genetic abnormalities (according to WHO 2008): AML with t(8;21)(q22;q22); RUNX1-RUNX1T1 AML with inv(16)(p13.1q22) or t(16;16)(p13.1;q22); CBFB-MYH11 AML with t(15;17)(q22;q12); PML-RARA (or variant translocations with other RARA gene fusions)

• AML with NPM1 mutation
• AML with FLT3 mutation
• Performance status WHO >2
• Patients with ejection fraction < 50% by Multi Gated Acquisition Scan (MUGA) or echocardiogram (ECHO scan) within 14 days of day 1
• Organ insufficiency (creatinine >1.5x upper normal serum level; bilirubin, AST or ALP >2.5x upper normal serum level, not attributable to AML; heart failure NYHA III/IV; severe obstructive or restrictive ventilation disorder)
• Uncontrolled infection
• Severe neurological or psychiatric disorder interfering with ability of giving an informed consent
• Patients with a "currently active" second malignancy other than non-melanoma skin cancers. Patients are not considered to have a "currently active" malignancy if they have completed therapy and are considered by their physician to be at less than 30% risk of relapse within one year.
• Known positive for Human immunodeficiency virus (HIV)
• Bleeding disorder independent of leukemia
• No consent for registration, storage and processing of the individual disease-characteristics and course as well as information of the family physician and/or other physicians involved in the treatment of the patient about study participation.
• No consent for biobanking.