Inclusion Criteria:

          -  Diagnosis of relapsed or refractory acute myeloid leukemia by World Health
             Organization (WHO) criteria. Unfit/frail patients with newly diagnosed AML are also
             eligible if not considered good candidates to receive a higher intensity therapy

               -  A patient is considered unfit or frail if has three or more of the five factor
                  below:

                    -  Unintentional weight loss of 10 pounds or more in a year

                    -  General feeling of exhaustion

                    -  Weakness as measured by grip strength

                    -  Slow walking speed

                    -  Low levels of physical activity

          -  Eastern Cooperative Oncology Group (ECOG) performance status score of =< 3

          -  Total serum bilirubin =< 2 x upper limit of normal (ULN). Patients with known
             Gilbert's syndrome may have a total bilirubin up to =< 3 x ULN

          -  Alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) =< 3 x ULN; or
             =< 5 x ULN in case of suspected leukemic liver involvement

          -  Serum creatinine =< 2.0 mg/dl

          -  Females of childbearing potential must have a negative serum or urine beta human
             chorionic gonadotropin (B-HCG) pregnancy test result within 1 week (+/-3 days) prior
             to the first dose of study drugs and must agree to use one of the following effective
             contraception methods during the study and for 30 days following the last dose of
             study drug. Effective methods of birth control include:

               -  Birth control pills, shots, implants (placed under the skin by a health care
                  provider) or patches (placed on the skin)

               -  Intrauterine devices (IUDs)

               -  Condom or occlusive cap (diaphragm or cervical/vault caps) used with spermicide

               -  Abstinence

               -  Females of non-childbearing potential are those who are postmenopausal greater
                  than 1 year or who have had a bilateral tubal ligation, oophorectomy, and/or
                  hysterectomy

          -  Males who have partners of childbearing potential must agree to use an effective
             contraceptive method (such as condom used with spermicide or abstinence) during the
             study and for 30 days following the last dose of study drug

          -  Patients or their legally authorized representative must provide written informed
             consent

        Exclusion Criteria:

          -  Patients with t(15;17) karyotype abnormality or acute promyelocytic leukemia

          -  History of another primary invasive malignancy that has not been definitively treated
             and in remission. Patients with non-melanoma skin cancers or with carcinomas in situ
             are eligible regardless of the time from diagnosis (including concomitant diagnoses)

          -  Presence of clinically significant uncontrolled central nervous system (CNS) pathology
             such as epilepsy, childhood or adult seizure, paresis, aphasia, stroke, severe brain
             injuries, dementia, Parkinson's disease, cerebellar disease, organic brain syndrome,
             or psychosis

          -  Evidence of active cerebral/meningeal disease. Patients may have history of CNS
             leukemic involvement if definitively treated with prior therapy and no evidence of
             active disease at the time of consent with at least 2 consecutive spinal fluid
             negative assessments for residual leukemia and negative imaging (imaging required only
             if previously showing evidence of CNS leukemia not otherwise documented by spinal
             fluid assessment)

          -  Patients with active unstable angina, concomitant clinically significant active
             arrhythmias, myocardial infarction within 6 months, or congestive heart failure New
             York Heart Association class III-IV. Patients with a cardiac ejection fraction (as
             measured by either multigated acquisition scan [MUGA] or echocardiogram) < 45% are
             excluded

          -  Patients with uncontrolled, active infections (viral, bacterial, or fungal)

          -  Known active hepatitis B or C infection, or known seropositivity for human
             immunodeficiency virus (HIV)

          -  Patients with liver cirrhosis or other serious active liver disease or with suspected
             active alcohol abuse

          -  Allogeneic hematopoietic cell transplantation (HSCT) within 6 months before the start
             of protocol-specified therapy, or with active acute/chronic graft-versus-host disease
             (GvHD) requiring systemic treatment; or receiving immunosuppression for GvHD
             prophylaxis within 2 weeks from the start of study therapy

          -  Prior chemotherapy/radiotherapy/investigational therapy within 2 weeks before the
             start of study drugs with the following exception:

               -  To reduce tumor burden, leukocytosis (circulating blast count) or palliation:
                  Intravenous cytarabine and/or hydroxyurea. No washout is necessary for these
                  agents. Patients must have recovered from acute non hematologic toxicity (to =<
                  grade 1) of all previous therapy prior to enrollment

          -  Females who are pregnant or lactating

          -  Male or female subjects of childbearing potential, unwilling to use an approved,
             effective means of contraception in accordance with institution's standards

          -  Other severe, uncontrolled acute or chronic medical or psychiatric condition or
             laboratory abnormality that in the opinion of the investigator may increase the risk
             associated with study participation or investigational product administration or may
             interfere with the interpretation of study results and/or would make the patient
             inappropriate for enrollment into this study

          -  Prior treatment with alvocidib

               -  Prior use of venetoclax single agent or any venetoclax-based combination therapy
                  is allowed