Inclusion Criteria:

1. Patients must have relapsed/refractory leukemias for which no standard therapies are
anticipated to result in a durable remission. Patients with poor-risk myelodysplasia
(MDS) [i.e. IPSS ≥ 1.5 or chronic myelomonocytic leukemia (CMML) are also candidates
for this protocol. Relapsed/refractory leukemias include acute non-lymphocytic
leukemia (AML) by WHO classification, acute lymphocytic leukemia (ALL), chronic
lymphocytic leukemia (CLL), or chronic myelogenous leukemia (CML) in blast crisis.
Patients with agnogenic myeloid metaplasia (AMM) are also eligible.

2. Age > 18 years.

3. ECOG performance status of 0-2.

4. 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. If the patient is on hydroxyurea to
control peripheral blood leukemic cell counts, the patient must be off hydroxyurea
for at least 48 hours before initiation of treatment on this protocol.

5. Persistent clinically significant chronic toxicities from prior chemotherapy, surgery
or radiotherapy must have resolved to NCI CTCAE Grade < 1, except for alopecia.

6. The following laboratory results, within 10 days of MKC-1 administration (unless the
abnormality is considered attributable to leukemia):

- Serum creatinine < 2.0 mg/dL

- Total bilirubin < ULN (unless a diagnosis of Gilbert's disease is present)

- AST < 2.5 x ULN (upper limit of normal)

- Serum albumin > 3.0 g/dL

7. Signed informed consent.

Exclusion Criteria:

1. Pre-existing hepatomegaly with disease measured as > 2 cm below the costal margin,
secondary to malignancy.

2. Pregnant or breast-feeding women. Female patients must be postmenopausal, surgically
sterile or they must agree to use a physical method of contraception. Female patient
with childbearing potential must have a negative pregnancy test within the 10 days
before the first MKC-1 administration. Male patients must be surgically sterile or
agree to use an acceptable method of contraception. Pregnant and nursing patients are
excluded because the effects of MKC-1 on a fetus or nursing child are unknown.

3. Clinical evidence of bowel obstruction, active uncontrolled malabsorption syndromes
or a history of total gastrectomy.

4. Impaired cardiac function including myocardial infarction within previous 3 months,
symptomatic coronary artery disease, arrhythmias not controlled by medication, or
uncontrolled congestive heart failure.

5. Patients receiving any other standard or investigational cytotoxic treatment for
their hematologic malignancy.

6. Treatment with antiretroviral therapy metabolized through CYP3A4 (including
indinavir, nelfinavir, ritonavir and saquinavir) due to the potential for drug
interactions wth MKC-1.

7. Any medical conditions that, in the investigator's opinion, would impose excessive
risk to the patient. Examples of such conditions include congestive heart failure of
Class III or IV of the NYHA classification, active infection, or any psychiatric
condition that would interfere with the understanding of the informed consent.