Inclusion Criteria:

(abbreviated)

1. Signed consent

2. AML patients:

1. above 60 years in first relapse or refractory.

2. 18-60 years 2nd relapse or refractory to at least two intensive chemotherapy
cycles.

3. above 60 years with high risk features (cytogenetics, secondary or treatment
related AML) d) above 60 years with myelodysplastic syndrome with >10% blasts in
bone marrow (WHO RAEB-2 (Refractory anemia with excess blasts-2)). For patients
below 60 years potential curative treatments should have been exhausted.

3. Performance status (ECOG) ≤ 2

4. Age ≥ 18 years

5. Acceptable liver, renal and bone marrow function as defined

6. Serum potassium within normal range.

7. Acceptable coagulation status as defined

8. Precautions for female patients with reproductive potential as defined

Exclusion Criteria:

1. Treatment with investigational agents within the last 4 weeks

2. Prior treatment with HDAC (Histone deacetylases) inhibitors including valproic acid

3. Prior anti-leukemic therapy (except hydroxyurea) within the last 3 weeks of trial
dosing

4. Co-existing active infection (including HIV) or any co-existing medical condition
likely to interfere with trial procedures, including significant cardiovascular
disease

5. Altered mental status precluding understanding of the informed consent process and/or
completion of the necessary study procedures.

6. Concurrent second malignancy.

7. History of hypersensitivity to idarubicin

8. Cumulative idarubicin dose exceeding 100 mg/m², or a (with respect cardiotoxicity)
corresponding dose of other anthracyclines

9. LVEF (left ventricular ejection fraction) below normal range (< 45% )

10. Known Central Nervous System (CNS) leukemia