Inclusion Criteria

Inclusion criteria:

1. Diagnosis of relapsed or refractory AML with at least one prior treatment for acute
myeloid leukemia.

2. Expression of CD33 on more than 30% of bone marrow blasts.

3. Eastern Cooperative Oncology Group Performance Status 0, 1 or 2

4. Age 18 years or older

5. Written informed consent which is consistent with International Conference on
Harmonization ¿ Good Clinical Practice (ICH-GCP) guidelines and local legislation.

Exclusion criteria:

1. Patients with acute promyelocytic leukemia according to WHO definition.

2. Patients with > 30.000 leukocytes/µl in the peripheral blood

3. Anti-leukemia therapy within two weeks before first treatment with BI 836858, 4 weeks
for biologics

4. Allogeneic stem cell transplantation within the last 3 months or with evidence of
graft versus host disease

5. Patients who are candidates for allogeneic stem cell transplantation.

6. Second malignancy currently requiring active therapy.

7. Symptomatic central nervous system involvement

8. Aspartate amino transferase (AST) or alanine amino transferase (ALT) greater than 2.5
times the upper limit of normal (ULN), or AST or ALT greater than 5 times the ULN for
those with Gilbert syndrome.

9. Prothrombin time (PT) >1.5 x ULN for subjects not on therapeutic vitamin K
antagonists (phenprocoumon, warfarin)

10. Bilirubin greater than 1.5 mg/dl (>26 µmol/L) unless elevation is thought to be due
to hepatic infiltration by AML, Gilbert syndrome, or hemolysis.

11. Serum creatinine greater than 2.0 mg/dl

12. Known human immunodeficiency virus (HIV) infection or active hepatitis B virus or
hepatitis C virus infection.

13. Concomitant intercurrent illness, which in the opinion of the Investigator would
compromise the evaluation of efficacy or safety of the trial drug, e.g. active severe
infection, unstable angina pectoris or cardiac arrhythmia

14. Psychiatric illness or social situation that would limit compliance with trial
requirements

15. Concomitant therapy, which is considered relevant for the evaluation of the efficacy
or safety of the trial drug

16. Female patients of childbearing potential who are sexually active and unwilling to
use a medically acceptable method of contraception during the trial and for 6 months
after the last administration of BI 836858

17. Male patients with partners of childbearing potential who are unwilling to use
condoms in combination with a second effective method of contraception during the
trial and for 6 months after the last administration of BI 836858

18. Pregnant or nursing female patients

19. Treatment with another investigational agent under the following conditions:

1. Within two weeks (4 weeks for biologics) of first administration of BI 836858;
or

2. Patient has persistent toxicities from prior anti-leukemic therapies which are
determined to be relevant by the Investigator.

3. Concomitant treatment with another investigational agent while participating in
this trial.

20. Prior treatment with a CD33 antibody

21. Patient unable or unwilling to comply with the protocol.