Inclusion Criteria:

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

          -  Subjects greater than or equal to 18 years of age at the time of signing consent.

          -  AML as defined by the WHO Classification 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) 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 than 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).

          -  No active tuberculosis in the setting of anti-TNF therapy - National guidelines should
             be followed for the appropriate tuberculosis screening in the setting of anti-TNF
             therapy, including a minimum of:

               -  Subject has a negative test for tuberculosis during screening defined as either:

                    -  Negative purified protein derivative (PPD) (< 5 mm induration at 48 to 72
                       hours after test is placed) OR

                    -  Negative quantiferon test

               -  Subjects with positive PPD and a history of bacillus Calmette-Guérin vaccination
                  are allowed with a negative Quantiferon test.

               -  Subjects with a positive PPD test (without a history of bacillus Calmette-Guérin
                  vaccination) or subjects with a positive or indeterminate Quantiferon test are
                  allowed if they have all of the following:

                    -  no symptoms, per tuberculosis worksheet provided by Amgen

                    -  documented history of a completed course of adequate treatment or
                       prophylaxis (per local standard of care) prior to the start of
                       investigational product

                    -  no known exposure to a case of active tuberculosis after most recent
                       prophylaxis

                    -  no evidence of active tuberculosis on chest radiograph within 3 months prior
                       to the first dose of investigational product (substudy subjects only)

        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 steroids for
             treatment of transfusion/hypersensitivity 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.

          -  History of multiple sclerosis or any other demyelinating disease.

          -  No active hepatitis secondary to alcoholic hepatitis or nonalcoholic steatohepatitis.