Inclusion Criteria:

1. Diagnosis of refractory or relapsed ALL or AML.

2. 12 months to 21 years of age at the time of informed consent.

3. Weight ≥10 kg

4. No chemotherapy, radiation, or major surgery within 2 weeks prior to first dose of
study drug and recovered from the toxic side effects of such therapy. In the
instance of rapidly progressive disease, anti-leukemia therapy may be administered
within the 2-week period as long as the subject has recovered from the toxic effects
of that therapy. Also, intrathecal therapy may be administered within the 2-week
period for subjects with CNS disease.

5. No stem cell transplant regimen within 3 months prior to first dose of study drug.

6. No conventional granulocyte colony stimulating factor (G-CSF) within 7 days prior to
the first dose of study drug, and no long-acting G-CSF (Neulasta) within 14 days
prior to the first dose of study drug.

7. No investigational therapy within 4 weeks prior to first dose of study drug.

8. Karnofsky Performance Status ≥50% for subjects ≥10 years of age and Lansky
Performance Status ≥60% for subjects <10 years of age. Subjects who are unable to
walk because of paralysis, but who are up in a wheelchair, will be considered
ambulatory for the purpose of assessing the performance status.

9. Adequate liver function [bilirubin ≤2 times the upper limit of normal (ULN) and serum
glutamic-pyruvic transaminase (SGPT) ≤5 times the ULN].

10. Adequate renal function (creatinine clearance ≥60 ml/min/1.73m2).

11. Adequate cardiac function [ejection fraction (EF) >50% or shortening fraction (SF)
>28% by echocardiogram or MUGA]

12. Informed consent signed by subject or legal guardian per investigational site
guidelines.

13. Able to comply with the requirements of the protocol.

14. Females of childbearing potential must have a negative serum or urine pregnancy test
within 72 hours prior to first dose of study drug.

15. All subjects (male and female) of childbearing potential must agree to practice
effective contraception during the entire study period, unless documentation of
infertility exists. Should a female become pregnant or suspect she is pregnant while
participating in this study, she should inform her treating physician immediately.

Exclusion Criteria:

1. Concomitant therapy that includes other chemotherapy that is or may be active against
ALL or AML, except for prophylaxis and/or treatment of opportunistic or other
infection with antibiotics, antifungals and/or antiviral agents. Concurrent
radiation therapy and immunosuppressive therapy are not allowed. Concurrent
intrathecal therapy per standard of care is allowed for subjects with CNS disease.

2. Any condition which, in the opinion of the Investigator, places the subject at
unacceptable risk if he/she were to participate in the study.

3. Clinically relevant serious co-morbid medical conditions including, but not limited
to, active infection, recent (≤6 months) myocardial infarction, unstable angina,
symptomatic congestive heart failure, uncontrolled hypertension, uncontrolled cardiac
arrhythmias, chronic obstructive or chronic restrictive pulmonary disease, and
cirrhosis, or psychiatric illness/social situations that would limit compliance with
study requirements. Cardiac patients with a New York Heart Association (NYHA)
classification of 3 or 4 will be excluded.

4. Active graft-versus-host disease (GVHD).

5. Pregnant, lactating, or not using adequate contraception.

6. Known allergy to doxorubicin or anthracyclines.

7. Any evidence of mucositis/stomatitis, except for Grade 1 mucositis/stomatitis due to
chronic GVHD.