Inclusion Criteria:

1. Written informed consent obtained according to international guidelines and local
law;

2. Male or female patients aged > 60 years without upper age limit;

3. Patients with primary or secondary AML according to WHO (≥ 20% blasts in the
peripheral blood (pB) or bone marrow (BM)) who are not expected to benefit from
standard remission-induction chemotherapy;

4. Patients with < 30 000 leukocytes/μl;

5. Performance status ECOG 0, 1, 2;

6. Creatinine < 2.0 mg/dl (unless leukemia-related);

7. Ability to understand the nature of the study and the study related procedures and to
comply with them.

Exclusion Criteria:

1. AML of FAB subtype M3;

2. Previous remission-induction chemotherapy for MDS or AML, previous allografting;

3. Previous treatment with DAC, 5-azacytidine, VPA or another HDAC inhibitor, or ATRA;

4. "Low-dose" chemotherapy (e.g. hydroxyurea, cytosine arabinoside (Ara-C), melphalan,
clofarabine etc.) within 4 weeks prior to DAC treatment, except for cytoreduction of
leukocytosis ≥ 30 000/μl with hydroxyurea or Ara-C as proscribed by the study
protocol (section 7.3 and 7.4); the patient must have recovered from all clinically
relevant reversible non-hematologic toxicities;

5. Treatment with tyrosine kinase inhibitors, immunomodulating agents (IMIDS) or other
investigational AML treatment within the last 4 weeks or in a time period of drug
half-life x 5 (whatever is shorter) before the first administration of DAC;

6. Treatment with cytokines within previous 4 weeks;

7. Concomitant therapy which is considered relevant for the evaluation of efficacy or
safety of the trial drug (i.e. other chemo- or immunotherapy);

8. Other malignancy requiring treatment (previous chemotherapy for other malignancies is
not an exclusion criteria);

9. Cardiac insufficiency NYHA IV;

10. Insufficient hepatic function (bilirubin, AST or ALT > = 2.5 x Upper Limit of Normal
(ULN)) (unless leukemia-related);

11. Fatal hepatic function disorder during treatment with valproic acid in siblings;

12. Hepatic porphyria;

13. Manifest serious pancreatic function disorder;

14. Plasmatic coagulation disorder not related to AML;

15. Known active hepatitis B or C;

16. Known HIV infection;

17. Other uncontrolled active infections;

18. Known allergy against soy beans or peanuts;

19. Psychiatric disorder that interferes with treatment;

20. Patient without legal capacity who is unable to understand the nature, significance
and consequences of the study;

21. Known hypersensitivity to, or intolerance of, one of the trial drugs, another
retinoid or the excipients of the trial drugs;

22. Concomitant use of any other investigational drug or participation in a clinical
trial within the last thirty days before the start of this study; simultaneous
participation in registry and diagnostic trials is allowed;

23. Female patients who are pregnant or breast feeding;

24. Fertile patients refusing to use safe contraceptive methods during the study (for
details see clinical trial protocol section 5.3);

25. Known or persistent abuse of medication, drugs or alcohol.