Inclusion Criteria:

1. Patients must have pathologically-confirmed acute leukemia, refractory or relapsed
after standard therapy for the disease or for which conventional systemic
chemotherapy is not reliably effective or no effective therapy is available Phase II
Only: Patient must have histologically or pathologically confirmed diagnosis of AML
based on WHO classification that is refractory after standard therapy, or for which
conventional systemic chemotherapy is not reliably effective, or no effective therapy
is available. Patients aged 60 years or older with newly diagnosed AML who are not
eligible for, or who refuse, standard care are also eligible.

2. Aged ≥ 18 years.

3. ECOG Performance Status of 0, 1 or 2.

4. Adequate clinical laboratory values (i.e., plasma creatinine <= 1.5 x upper limit of
normal (ULN) for the institution, bilirubin <=1.5 x ULN, alanine transaminase (ALT)
and aspartate transaminase (AST) <= 2.5 x ULN).

5. Absence of CNS involvement by leukemia.

6. Absence of uncontrolled intercurrent illnesses, including uncontrolled infections,
cardiac conditions, or other organ dysfunctions.

7. Signed informed consent prior to the start of any study specific procedures.

8. Women of child-bearing potential must have a negative serum or urine pregnancy test.
Male and female patients must agree to use acceptable contraceptive methods for the
duration of the study and for at least one month after the last drug administration.

Exclusion Criteria:

1. The interval from prior treatment to time of study drug administration is < 2 weeks
for cytotoxic agents or < 5 half-lives for noncytotoxic agents. Exceptions: Use of
hydroxyurea is allowed before the start of study and may be administered up to day 5
of the first cycle.

2. Any >grade 1 persistent clinically significant toxicities from prior chemotherapy.

3. Extensive prior radiotherapy to more than 30% of bone marrow reserves, or prior bone
marrow/stem cell transplantation.

4. Any concomitant condition that in the opinion of the investigator could compromise
the objectives of this study and the patient's compliance.

5. A pregnant or lactating woman.

6. Current malignancies of another type. Exceptions: Patients may participate if they
have previously treated and currently controlled prostate cancer, adequately treated
in situ cervical cancer and basal cell skin cancer or other malignancies with no
evidence of disease for 2 years or more.

7. Patient has acute promyelocytic leukemia (APL).

8. Patients with known HIV, HBV or HCV infection (note: testing for these infections is
not required).

9. Documented or known clinically significant bleeding disorder.