Defining the HER2 Positive (+) Breast Cancer Kinome Response to Trastuzumab, Pertuzumab, Combination Trastuzumab +Pertuzumab, or Combination Trastuzumab + Lapatinib

Until recently, our understanding of the kinome has been limited to just 5-10% of the
genome-encoded kinases. This limited knowledge prevents a thorough understanding of
resistance mechanisms, and precludes individualizing HER2-targeted therapy in HER2+ disease.
Fortunately, we have now developed a chemical proteomics approach to define comprehensive
kinome activity in cells and tumors (MIB/MS).[1]

We hypothesize that our proteomics approach can be used to characterize the heterogeneity of
the kinome activation profiles in HER2+ breast cancer and permit us to identify if adaptive
response to HER2 inhibition differs depending on the anti-HER2 drug mechanism of action. This
will allow rational prediction of new combinatorial therapies in future clinical trials.

To explore kinome activation in this population, we propose a window trial in stage I-IV
HER2+ patients scheduled to undergo definitive surgery (either lumpectomy, mastectomy or
surgical resection of oligometastatic disease). Enrolled patients will be randomized to one
of four treatment arms; A) single dose trastuzumab; B) single dose pertuzumab; C) combination
trastuzumab + pertuzumab for one dose each; or D) combination single dose trastuzumab plus
lapatinib daily for one week.

Dosing in each arm will be initiated 7 days prior to surgery, with pre- and post-dosing
tissue samples analyzed for kinome response and resistant signatures. To ensure adequate
levels of trastuzumab and pertuzumab at the time of surgery, a loading dose of each agent (8
mg/kg IV for trastuzumab, and 840 mg IV fixed dose for pertuzumab) were chosen. The dose of
lapatinib was based on prior studies of lapatinib administered in combination with
trastuzumab. Given the varied pharmacokinetic profiles of the three agents and limited
dosing, we expect exposure levels of the agents to be different relative to respective steady
state levels. Therefore qualitative rather than quantitative measures will be key.

Inclusion Criteria:

- Signed, written informed consent

- Age >/= 18 years

- Histologically confirmed HER2+ breast cancer: IHC 3+ or fluorescence in situ
hybridization [FISH] amplified; by clinical assay on either primary or metastatic
tumor

- Stage I-IV disease

- For patients with Stage I-IIIc disease:

1. Scheduled for lumpectomy or mastectomy

2. No prior or current therapy for breast cancer

3. Not considered a candidate for therapeutic neoadjuvant treatment

- For patients with Stage IV disease:

1. Scheduled for surgical resection of oligometastatic disease

2. Previously untreated for breast cancer

- Normal relevant end organ function as defined by the following:

- ANC>1500 cells/mL

- Platelets > 100,000 cells/mL

- Hemoglobin > 10 g/dL

- Total bilirubin ≤ 1.5 x ULN (unless known Gilbert's syndrome)

- AST and ALT ≤ 2.5 X ULN

- Creatinine ≤ 1.5 X ULN OR Calculated creatinine clearance ≥50 mL/min OR 24-hour
urine creatinine clearance ≥50 mL/min

- Left Ventricular Ejection Fraction ≥ 50% by ECHO (preferred) or MUGA

- For women of childbearing potential, agreement to use an effective form of
contraception (patient and/or partner, e.g., surgical sterilization, a reliable
barrier method, birth control pills, or contraceptive hormone implants) and to
continue its use for the duration of the study treatment, and for a minimum of 6
months following trastuzumab and/or pertuzumab administration.

- Sufficient fresh or frozen tissue remaining from pre-treatment core biopsy/ incisional
biopsy or willing to undergo biopsy (at UNC via LCCC9819) for research purposes only
(approximately 10mg or one core's worth of tissue needed)

- Surgeon and medical oncologist agree one week window trial is appropriate/safe for the
patient and that surgery appointment can accommodate treatment schedule as outlined in
the study schema (section 4.1).

- UNC patients must co-enroll into LCCC9819 for collection of tissue samples

Exclusion Criteria:

- Pregnant or lactating female

- Prior radiation therapy to the target lesion

- Use of any investigational drug within 28 days or five half-lives, whichever is
shorter, prior to the first dose of study medication; a minimum of 10 days between
termination of the investigational drug and treatment with study medication is
required

- Any major radiotherapy, tumor-directed systemic or immunotherapy within the last 4
weeks for any indication

- Candidate for therapeutic neoadjuvant treatment

- Active infection

- Evidence of severe or uncontrolled systemic diseases (e.g., unstable or uncompensated
respiratory, hepatic, renal, or cardiac disease)

- Required administration of concomitant moderate or strong inhibitors or inducers of
CYP3A4 for 14 days prior to the first dose of study drug prior amiodarone for up to 6
months prior to day 1 of study treatment

- Inability to take oral medications e.g., impairment of gastrointestinal (GI) function
or GI disease that may significantly alter the absorption of oral medications (e.g.,
ulcerative diseases, uncontrolled nausea, vomiting, diarrhea, malabsorption syndrome,
or small bowel resection)

- History or evidence of cardiovascular risk including any of the following:

- Current uncontrolled hypertension (systolic >150 mm Hg and/or diastolic >100
mmHg) or unstable angina

- History of serious cardiac arrhythmia requiring treatment (exceptions: atrial
fibrillation, paroxysmal supraventricular tachycardia)

- History of myocardial infarction within 6 months of day 1 of dosing

- History of CHF of New York Heart Association (NYHA) criteria

- Known human immunodeficiency virus (HIV), Hepatitis B Virus (HBV), or Hepatitis C
Virus (HCV) infection (with the exception of chronic or cleared HBV and HCV infection
which will be allowed)

- Have acute or currently active/requiring anti-viral therapy hepatic or biliary disease
(with the exception of patients with Gilbert's syndrome, asymptomatic gallstones,
liver metastases or stable chronic liver disease per investigator assessment).

- Known immediate or delayed hypersensitivity reaction or idiosyncrasy to drugs
chemically related to the study drugs

- Psychological, familial, sociological, or geographical conditions that do not permit
compliance with the protocol

- Any other concurrent condition that in the investigator's opinion would jeopardize
compliance with the protocol