Inclusion Criteria:

- Patients must have:

- AML, ALL, or high-risk MDS (RAEB or RAEB-t) that has:

- Not responded (no CR) to initial induction chemotherapy, or

- Recurred after an initial CR of < 1 year, or

- Recurred after an initial CR of > 1 year and failed to respond to an
initial reinduction attempt, or

- Recurred more than once, or

- Chronic myeloid leukemia in myeloid blast phase

- Patients with CML blast phase may receive BMS-214662 as their first therapy
for blast phase or after failing other treatments for blast phase

- Patients with refractory or relapsed acute promyelocytic leukemia are eligible
provided they have failed an ATRA-containing regimen

- Performance status of =< 0-2

- Signed informed consent indicating that patients are aware of the investigational
nature of this study in keeping with the policies of the hospital

- Patients must have been off chemotherapy for the 4 weeks prior to entering this study
and recovered from the toxic effects of that therapy; patients with evidence of
rapidly progressive disease (i.e., absolute peripheral blood blast count >= 5 x
10^9/L and increasing by >= 1 x 10^9/L/24 hours) may receive treatment before 4 weeks
from the previous treatment providing they have recovered from all toxic effects of
that therapy; use of hydroxyurea on patients with rapidly proliferative disease is
allowed up to 24 hours prior to the start of therapy

- Bilirubin =< 1.5 mg/dL

- Creatinine =< 1.5 mg/dL or creatinine clearance >= 60 mL/hr

- Patients who are likely to benefit from allogeneic bone marrow transplantation (i.e.,
age < 60 years of physiological age with histocompatible donor) should be excluded
from this study unless such therapy is not feasible

Exclusion Criteria:

- Pregnant and nursing females will be excluded; patients of childbearing potential
should practice effective methods of contraception

- Patients with prolonged QTc interval on EKG are excluded