Inclusion Criteria:

- Histologically or cytologically confirmed advanced or metastatic adenocarcinoma of
the breast

- 18 years or older

- Karnofsky performance status greater than or equal to 70%

- Radiographic or physical examination evidence of at least one site of
unidimensionally-measurable disease, using the Response Evaluation Criteria in Solid
Tumors (RECIST) criteria

- Must have failed both a taxane and an anthracycline, given sequentially or in
combination, either in an adjuvant or metastatic setting

- All acute toxicity of any prior chemotherapy, surgery or radiotherapy must have
resolved to National Cancer Institute Common Toxicity Criteria (NCI CTC) Grade less
than or equal to 1

- Lab results, within 10 days of MKC-1 administration:

- Hemoglobin less than or equal to 9 g/dL

- Absolute neutrophil count greater than or equal to 1.5 x 10^9/L

- Platelet count greater than or equal to 75 x 10^9/L

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

- AST less than or equal to 2.5 x ULN

- Serum albumin greater than or equal to LLN (lower limit of normal)

- Total bilirubin less than or equal to ULN

- Alkaline phosphatase less than or equal to 2.5 x ULN

- Signed informed consent

Exclusion Criteria:

- Pre-existing hepatomegaly with disease measures greater than or equal to 2 cm below
the costal margin, secondary to malignancy

- Administration of cancer specific therapy within the following periods prior to study
drug initiation:

- chemotherapy less than 3 weeks prior

- hormonal therapy less than one week prior

- radiation therapy less than 2 weeks prior

- Be pregnant or lactating; not employing effective birth control

- Known central nervous system (CNS) metastases unless treated, clinically stable and
not requiring steroids

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

- Administration of any investigational agent (therapeutic or diagnostic) within 4
weeks prior to receipt of study medication

- Uncontrolled hypercalcemia (serum calcium-corrected greater than 12 mg/dL)

- Serious cardiac condition

- Any medical conditions that, in the investigator's opinion would impose excessive
risk to the patient

- Patients with previous malignancies unless free of recurrence for at least 5 years
except basal cell carcinoma of the skin or carcinoma-in-situ of the uterine cervix

- Treatment with antiretroviral therapy metabolized through CYP3A4