Key

Inclusion Criteria:

- The patient has histologically proven acute lymphocytic leukemia (ALL) or acute
myeloid leukemia (AML) that has relapsed or is refractory to the last regimen, and
the patient is without alternative curative therapy.

- The patient's last myelosuppression therapy ended at least 2 weeks before the first
dose of study drug.

- Nonhematologic acute toxic effects of prior therapy have resolved to grade 2 or less
according to National Cancer Institute (NCI) Common Terminology Criteria for Adverse
Events (CTCAE).

- The patient has adequate liver function with bilirubin values less than or equal to
1.5 times the upper limit of normal (ULN) and aspartate aminotransferase (AST) and
alanine aminotransferase (ALT) values less than or equal to 5 times the
age-appropriate ULN.

- The patient has adequate renal function with serum creatinine values less than 2
times ULN.

- The patient has Karnofsky or Lansky performance status of 60 or greater. Patients
older than 16 years of age will be scored according to the Karnofsky scale and
patients 16 years of age or younger will be scored according to the Lansky scale.

- The patient may have had hematopoietic stem cell transplantation.

- Women of childbearing potential (not surgically sterile) must use a medically
accepted method of contraception and must agree to continue use of this method for
the duration of treatment and for 30 days after the end of treatment.

- Men not surgically sterile or who are capable of producing offspring must practice
abstinence or use a barrier method of birth control, and must agree to continue use
of this method for the duration of treatment and for 30 days after the end of
treatment.

- The patient must be willing and able to comply with study restrictions and to remain
at the clinic for the required duration during the study period, and willing to
return to the clinic for the follow-up evaluation as specified in this protocol.

Key Exclusion Criteria:

- The patient has any active, uncontrolled systemic infection, severe concurrent
disease, or symptomatic untreated central nervous system (CNS) involvement.

- The patient has evidence of active graft versus host disease.

- The patient has a known human immunodeficiency virus (HIV) infection.

- The patient has active hepatitis B or hepatitis C infection.

- The patient is a pregnant or lactating woman. Any women becoming pregnant during the
study will be withdrawn from the study immediately.

- The patient has any serious uncontrolled medical or psychological disorder that would
impair the ability of the patient to receive study drug.

- The patient has any condition that places the patient at unacceptable risk or
confounds the ability of the investigators to interpret study data.

- The patient has received any other investigational agent within 30 days of study
entry.

- The patient has known hypersensitivity to bendamustine or mannitol.