Phase II Short-term Adjuvant Therapy and Biomarker Studies With Targeted Agents in Women With Estrogen Receptor Negative Breast Cancer

Study Drug Administration:

If you are found to be eligible to take part in this study, you will be randomly assigned (as
in the flip of a coin) to 1 of 3 study groups:

- If you are in Group 1, you will take dasatinib 40mg once a day by mouth with water.

- If you are in Group 2, you will take dasatinib 80mg once a day by mouth with water.

- If you are in Group 3, you will not receive dasatinib.

You will be given a study drug diary to complete. In the diary, you will record when you take
the study drug.

Study Visits:

At Month 1:

- You will be called by a nurse and asked about any drugs you are taking and side effects
you may be having.

- You will be asked about any drugs you may be taking and side effects you may be having.

- Your drug diary will be reviewed.

At Month 2 you will be called by a nurse and asked about any drugs you are taking and side
effects you may be having. You will also be asked to review your drug diary. This call will
take about 20 minutes

At Month 3 (or if you leave the study early):

- You will have a fine needle aspirate (FNA) of the breast for biomarker testing.
Biomarkers are found in the blood/tissue and may be related to your reaction to the
study drug.

- Blood (about 2-3 tablespoons) will be drawn for biomarker testing.

- You will be asked about any drugs you may be taking and side effects you may be having.

- Your drug diary will be reviewed.

Length of Study:

You may remain on study for up to 3 months. You will no longer be able to take the study drug
if the disease gets worse, if intolerable side effects occur, or if you are unable to follow
study directions.

Inclusion Criteria:

1. Histological confirmation of ER negative breast carcinoma (defined as less than 10%),
stage I, II, or III

2. Completed all adjuvant therapy including (if indicated) endocrine, trastuzumab,
radiation therapy

3. At least 18 years of age.

4. Female: A female is eligible to enter and participate in the study if she is of: a.
Non-childbearing potential (i.e., women with functioning ovaries who have a current
documented tubal ligation, hysterectomy alone, hysterectomy and bilateral
salpingo-oophorectomy, bilateral salpingo-oophorectomy alone or women who are
post-menopausal); or b. Childbearing potential (i.e., women with functioning ovaries
and no documented impairment of oviductal or uterine function that would cause
sterility. This category includes women with oligomenorrhoea (severe), women who are
perimenopausal, and young women who have begun to menstruate), has a negative serum
pregnancy test at screening, and agrees to one of the following where considered
acceptable to the local IRB/IEC: • Double-barrier contraception (condom with
spermicidal jelly, foam suppository, or film; diaphragm with spermicide; or male
condom and diaphragm).

5. (Continued from above) • Abstinence from sexual intercourse from 2 weeks prior to
administration of the investigational product, throughout the active study treatment
period. • Male partner who is sterile prior to the female subject's entry into the
study and is the sole sexual partner for that female subject. • Any intrauterine
device (IUD). • Barrier methods including diaphragm or condom with a spermicide.

6. Able to swallow and retain oral medication.

7. ECOG (Eastern Cooperative Oncology Group) performance status 0 to 2.

8. Provided written informed consent.

9. Adequate bone marrow function: Hemoglobin >/= 9 gm/dL. • Absolute granulocyte count
>/= 1,500/mm^3 (1.5 x 10^9/L). • Platelets >/= 75,000/mm^3 (100 x 10^9/L).

10. Serum creatinine < 1.4 mg/dL or calculated creatinine clearance (CrCl) >/= 30 mL/min

11. Total bilirubin
12. Aspartate and alanine transaminase (AST or ALT) reference range.

13. Patients must have a baseline ECG with QTcF within the normal range within 28 days
prior to registration.

14. Normal mammogram of unaffected breast within 12 months prior to study entry.

Exclusion Criteria:

1. Unwillingness to undergo RPFNA.

2. Contraindication to RPFNA including breast implant(s), bilateral radiation,
anticoagulation (excluding those on 81mg aspirin).

3. Concurrent medical condition that would increase drug toxicity: Pleural or pericardial
effusion, coagulation or platelet function disorder, ongoing or recent (less than 3
months gastrointestinal bleeding)

4. Uncontrolled angina, congestive heart failure, MI (within last 6 months), congenital
long QT syndrome, history of clinically significant ventricular arrhythmia, prolonged
QTcF interval on pre-entry EKG (greater than normal range)

5. Hypokalemia or hypomagnesemia if it cannot be corrected

6. Is a pregnant or lactating female.

7. Has evidence of recurrent or metastatic (Stage IV) breast cancer.

8. Is considered medically unfit for the study by the investigator as a result of the
medical interview, physical exam, or screening investigations.

9. Has a known immediate or delayed hypersensitivity reaction or idiosyncrasy to
dasatinib

10. Has received treatment with any investigational drug in the previous 4 weeks.

11. Has received chemotherapy, immunotherapy, biologic therapy or endocrine therapy within
the past 12 weeks.

12. Is currently receiving oral steroid treatment (inhaled steroids are permitted)

13. Oral estrogen, progesterone, testosterone therapy within last 3 months.

14. Concomitant Medications: Drugs that are considered category D (Consider therapy
modification) and X (Avoid combination) using the Lexicomp database are prohibited.
Concomitant drugs that fall into categories A (No known interaction), B (no action
needed) and C (monitor therapy) are allowed.