PH 2 ADI-PEG 20 Acute Myeloid Leukemia

Inclusion Criteria:

1. Acute myeloid leukemia (AML) diagnosed by morphologic, histochemical or cell surface
marker criteria.

2. Patients with AML must have either:

(a) relapsed or refractory leukemia after receiving at least one prior conventional
induction therapy. Those in early first relapse must not have a matched donor and/or
they must not be a candidate for allogeneic stem cell transplantation (usually this
would mean the patient is too ill, obese, has a co-morbid condition or is over the age
of 55 years) or (b) poor-risk AML as defined below: (i) Treatment related AML, except
if it is associated with favorable cytogenetics (e.g., inversion 16, t(16;16),
t(8;21), t(15;17), and not a candidate for stem cell transplantation, or (ii) AML with
an antecedent hematologic disease (e.g., MDS, myelofibrosis, polycythemia vera, etc.),
and not a candidate for stem cell transplantation.

(iii) De novo AML > 70 years of age. (iv) AML with unfavorable cytogenetics regardless
of age (>18 years), if patients are not candidates for allogeneic transplantation.
Unfavorable cytogenetics are the following: complex (>3 abnormalities), -7, -5, 7q-,
5q-, abnormalities of 11q23 excluding t(9;11), t(9;22), inversion 3, t(3;3), t(6;9).

(c) Patients older than 60 years of age who had AML (i.e., > 20% bone marrow blasts)
and no prior therapy for AML

3. Age ≥ 18 years.

4. ECOG performance status of 0-2.

5. Post-menarche female subjects and male subjects must be asked to use appropriate
contraception for both the male and female for the duration of the study. Subjects
must agree to use two forms of contraception or agree to refrain from intercourse for
the duration of the study. Females must not be pregnant at the start of the study, and
a serum human chorionic gonadotropin (HCG) pregnancy test must be negative before
entry into the study.

Exclusion Criteria:

1. Patients with infections requiring intravenous (IV) antibiotic/antiviral therapy are
not eligible for entry onto the study; patients on prophylactic antibiotics or
antivirals are acceptable.

2. Pregnancy or lactation.

3. Expected non-compliance.

4. Uncontrolled intercurrent illness including, but not limited to, ongoing or active
infection, symptomatic congestive heart failure (New York Heart Association Class III
or IV), cardiac arrhythmia, psychiatric illness, social situations that would limit
compliance with study requirements or DIC.

5. Subjects who have had any anticancer treatment prior to entering the study and have
not recovered to baseline (except alopecia) or≤ Grade 1 AEs, or deemed irreversible
from the effects of prior cancer therapy. AEs > Grade 1 that are not considered a
safety risk by the Sponsor and investigator may be allowed upon agreement with both.

6. Subjects with history of another primary cancer, including co-existent second
malignancy, with the exception of: a) curatively resected non-melanoma skin cancer; b)
curatively treated cervical carcinoma in situ; or c) other primary solid tumor with no
known active disease present in the opinion of the investigator will not affect
patient outcome in the setting of current diagnosis.