To identify the maximum tolerated dose or recommended dose for further development of volasertib in combination with azacitidine in Japanese patients with myelodysplastic syndromes or chronic myelomonocytic leukemia, and evaluate the safety and tolerability, pharmacokinetics and the preliminary efficacy of this combination.

Inclusion criteria:

1. Patients of age >=20 and <=80 years

2. Patients with primary or treatment-related myelodysplastic syndrome (MDS) or chronic myelomonocytic leukemia (CMML), who are not eligible for hematopoietic stem cell transplantation based on the investigator's judgment, that meet one of the following criteria:

   • Intermediate-2 and high-risk MDS according to the International Prognostic Scoring System, in the setting of 5-30% bone marrow blasts
   • CMML with >= 10% marrow blasts without myeloproliferative disorder (white blood cell count of <13,000/ µL)

3. Patients with no prior azacitidine treatment, or with prior azacitidine treatment that meet one of the following criteria:

   • Patients failing to achieve haematological improvement, partial remission, marrow complete remission or complete remission after 3 cycles of azacitidine or progressed at any time after start of azacitidine
   • Patients achieved an initial response and subsequently develop disease progression or relapse

4. Eastern Cooperative Oncology Group performance status score 0 or 1 at screening

5. Signed written informed consent consistent with Good Clinical Practice.

Exclusion criteria:

1. Treatment with systemic therapy for MDS, including an investigational drug, within 14 days before the first dose of study treatment, except for lenalidomide within 12 weeks before the first dose of study treatment, or lack of recovery from any acute toxicities pertinent to the prior systemic therapy.
2. Prior treatment with volasertib
3. Contraindications for azacitidine treatment according to the manufacturer's product information
4. Known hypersensitivity to the trial drugs or its excipients
5. Concomitant malignancy currently requiring active therapy (except for hormonal/anti-hormonal treatment, e.g. in prostate or breast cancer)
6. QTcF prolongation >470 ms or QT prolongation deemed clinically relevant by the investigator (e.g., congenital long QT syndrome).
7. Total bilirubin >1.5 x upper limit of normal (ULN) not related to Gilbert's syndrome, hemolysis, or secondary to MDS at screening
8. Aspartate amino transferase or alanine amino transferase >2.5 x ULN
9. Serum creatinine >1.5 x ULN at screening
10. Arterial oxygen pressure <60 torr or arterial oxygen saturation <92% (at room air)
11. Active hepatitis B or hepatitis C, or laboratory evidence of hepatitis with positive results of hepatitis B surface antigen and/or hepatitis C antibody.
12. Human immunodeficiency virus infection.
13. Severe illness or organ dysfunction involving the heart, lung, kidney, liver or other organ system, which in the opinion of the investigator would interfere with the evaluation of the safety of the study treatment including; infection requiring active treatment, poorly controlled ventricular/atrial tachyarrhythmia, use of heart pacer, unstable angina pectoris, history of myocardial infarction or severe congestive heart failure, clinically unstable cardiac or pulmonary disease
14. Any significant concurrent psychiatric disorder or social situation that according to the investigator's judgment would compromise patient's safety or compliance, interfere with consent, study participation, or interpretation of study results
15. All male patients and female patients of child bearing potential who are unwilling to use a medically acceptable method of contraception during the trial and at least 6 months after the end of study treatment (i.e. hormonal contraception, intrauterine device, condom with spermicide, etc.). Note: females are considered to be of child bearing potential unless they have been surgically sterilized or are post-menopausal (complete absence of menses for at least 12 months without other medical reasons).
16. Pregnant or nursing female patients
17. Known or suspected active alcohol or drug abuse