Study Evaluating the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics and Efficacy of AMG 427 in Subjects With Relapsed/Refractory Acute Myeloid Leukemia.

Inclusion Criteria:

- Subject has provided informed consent prior to initiation of any study-specific
activities/procedures.

- Subjects greater than or equal to18 years of age at the time of signing consent.

- AML as defined by the WHO Classification (Appendix D) as persisting or recurring
following 1 or more treatment courses (exceptions noted in exclusión criteria).

- Myeloblasts greater than or equal to 5% in bone marrow, as confirmed by
immunophenotype by flow cytometry.

- Eastern Cooperative Oncology Group (ECOG, Appendix F) Performance Status of less than
or equal to 2.

- Renal function as follows: serum creatinine greater than 2.0 mg/dL (176.84 mol/L);
estimated glomerular filtration rate (eGFR) less tan 30 mL/min/1.73 m2.

- Hepatic function as follows:aspartate aminotransferase (AST) and alanine
aminotransferase (ALT) less tan or equal to 3.0 x upper limit of normal (ULN);
bilirubin less than or equal to 1.5 x ULN (unless considered due to Gilbert's syndrome
or hemolysis).

Exclusion Criteria:

- Patients with acute promyelocytic leukemia (APML).

- Active extramedullary AML in the central nervous system (CNS)

- Known hypersensitivity to immunoglobulins.

- White blood cells (WBC) greater than 15,000 cells/mcL (15 cells x 10^9/L) at screening
(hydroxyurea is permitted to enable eligibility).

- Prior malignancy (other than in situ cancer) unless treated with curative intent and
without evidence of disease for greater than 2 years before screening.

- Autologous HSCT within 6 weeks prior to start of AMG 427 treatment.

- Allogeneic HSCT within 3 months prior to start of AMG 427 treatment.

- Any graft-versus-host disease requiring systemic therapy with immunomodulators.

- History or evidence of significant cardiovascular risk including any of the following:
symptomatic congestive heart failure, unstable angina, clinically significant
arrhythmias (eg, ventricular fibrillation, ventricular tachycardia etc.), recent
coronary angioplasty, intra-cardiac defibrillators or any clinically relevant
concurrent disorder that may pose a risk to subject safety or interfere with study
evaluation, procedures, or completion.

- History of arterial thrombosis (eg, stroke or transient ischemic attack) in the past 3
months.

- Active infection requiring intravenous antibiotics within 1 week of study enrollment
(day 1). Antibiotics may be administered for prophylaxis as per institutional
standards up to and after enrollment.

- Known positive test for human immunodeficiency virus (HIV).

- Positive for hepatitis B surface antigen (HepBsAg).

- Positive for hepatitis C or chronic hepatitis C. Possible exceptions: acute hepatitis
C and completely cleared of the virus (demonstrated by negative viral load), chronic
hepatitis C with undetectable viral load defined by sustained virologic response 24
weeks (SVR24) after completion of anti-hepatitis C treatment.

- Live vaccination(s) within 4 weeks before the start of AMG 427 treatment on day 1,
during treatment, and until the end of the last study dose.

- Unresolved toxicities from prior antitumor therapy, defined as not having resolved to
Common Terminology Criteria for Adverse Events (CTCAE), version 4.0 grade 1 (with the
exception of myelosuppression, eg, neutropenia, anemia, thrombocytopenia), or to
levels dictated in the eligibility criteria with the exception of alopecia or
toxicities from prior antitumor therapy that are considered irreversible (defined as
having been present and stable for greater than 2 months) which may be allowed if they
are not otherwise described in the exclusion criteria AND there is agreement to allow
by both the investigator and sponsor.

- Antitumor therapy (chemotherapy, antibody therapy, molecular-targeted therapy, or
investigational agent) within 14 days of day 1. Exception: hydroxyurea to control
peripheral blood leukemic cell counts is allowed until start of investigational
product treatment.

- Treatment with systemic immune modulators including, but not limited to, nontopical
systemic corticosteroids, cyclosporine, and tacrolimus within 2 weeks before
enrollment (day 1). Exceptions: physiologic replacement steroids or hydrocortisone for
treatment of transfusion reactions.

- Major surgery within 28 days of study day 1 with the exception of biopsy and insertion
of central venous catheter.

- History or evidence of any other clinically significant disorder, condition or disease
that, in the opinion of the investigator or Amgen medical monitor would pose a risk to
subject safety or interfere with the study evaluation, procedures or completion.

- Males and females of reproductive potential who are unwilling to practice a highly
effective method(s) of birth control while on study through 4 weeks after receiving
the last dose of study drug. Acceptable methods of highly effective birth control
include sexual abstinence (males, females); vasectomy; bilateral tubal
ligation/occlusion; or a condom with spermicide (men) in combination with hormonal
birth control or intrauterine device (IUD) (women).

- Females who are lactating/breastfeeding or who plan to breastfeed while on study
through 4 weeks after receiving the last dose of study drug.

- Females with a positive pregnancy test.

- Females planning to become pregnant while on study through 4 weeks after receiving the
last dose of study drug.

- Subjects likely to not be available to complete all protocol-required study visits or
procedures, and/or to comply with all required study procedures to the best of the
subject's and investigator's knowledge.