Inclusion Criteria:

ARM A and B: Phase I CP-4055 single agent 1. Patients must have relapsed/refractory
leukemias for which no standard therapies are anticipated to result in a durable response
or have failed potentially curative therapy, or have refused or are considered unsuitable
for standard therapy

ARM C: CP-4055 in combination with idarubicin

1. Patients with relapsed/refractory AML for which no standard therapies are anticipated
to result in a durable response or who have failed potentially curative therapy, or
who refuse or are considered unsuitable for standard therapy

ARM A, B, C: CP-4055 as single agent and/or in combination with idarubicin

2. Patients must be 18 years of age or older

3. Patients must have ECOG performance status (PS) of 0 - 2. See Appendix 3

4. Women of child-bearing potential (i.e., women who are pre-menopausal or not
surgically sterile) must have a negative serum or urine pregnancy test within 2 weeks
prior to beginning treatment on this study. Nursing patients are excluded.

Male and female patients must use acceptable contraceptive methods for the duration
of time on study, and males also for 3 months after the last CP-4055 dose

5. Patients must be capable of understanding and complying with parameters as outlined
in the protocol, and able and willing to sign a written informed consent form

6. In the absence of rapidly progressing disease, the interval from prior treatment to
time of study drug administration should be at least 2 weeks for cytotoxic agents, or
at least 5 half-lives for noncytotoxic agents.

7. Patients must have the following clinical laboratory values:

- Serum creatinine less or equal to 1.5 x the institutional upper limit of normal
(ULN)

- Total bilirubin less or equal to 1.5 x the ULN unless considered due to
Gilbert's syndrome

- Alanine aminotransferase (ALT) (SGPT), or aspartate aminotransferase (AST)
(SGOT) less or equal to 2.5 x the ULN unless considered due to organ leukemic
involvement

Phase II

1. Patients with a confirmed diagnosis of AML who have received cytotoxic chemotherapy

2 - 7. Identical to inclusion criteria nos. 2 - 7 for phase I

Exclusion Criteria:

Phase I AND II

1. A history of allergic reactions or sensitivity attributed to compounds of similar
chemical or biologic composition to CP-4055, i.e., ara-C and/or egg

2. Known positive status for human immunodeficiency virus (HIV) or hepatitis B or C

3. Pregnant and nursing patients are excluded

4. Uncontrolled intercurrent illness

5. Active heart disease

6. Patients receiving any other standard or investigational cytotoxic treatment for
their hematologic malignancy other than a maximum of 5 g of hydroxyurea to a maximum
of 5 days in cycle 1 of therapy

7. Any medical condition which in the opinion of the investigator places the patient at
an unacceptably high risk for toxicities

Exclusion criteria no. 8 applies only in arm C:

8. Patients with hypersensitivity to idarubicin or any other component of the product,
and/or other anthracyclines or anthracenediones