PRIMARY OBJECTIVES:
I. To determine if 3-year recurrence-free survival (RFS) is greater than 92% among
clinical stages II or IIIa patients with HER2-positive breast cancer who achieve
pathologic complete response (pCR) (ypT0/is ypN0) after preoperative therapy with 12
weeks of a taxane, trastuzumab (or Food and Drug Administration [FDA] approved
biosimilar) and pertuzumab (THP x 12).
SECONDARY OBJECTIVES:
I. To determine 3-year IDFS (invasive disease-free survival), DDFS (distant disease-free
survival), DRFS (distant relapse-free survival), RFI (recurrence-free interval), OS
(overall survival) and breast cancer-specific survival in patients who achieve pCR (and
by pretreatment clinical stage). (Secondary Clinical Objective) II. To determine 3-year
EFS (event-free survival) in all patients from time of study registration. (Secondary
Clinical Objective) III. To evaluate safety and tolerability for all patients during the
pre-operative phase and for patients who attain pCR and de-escalate therapy (Arm A) until
the completion of post-surgery protocol assigned therapy (i.e. until the end of
trastuzumab and pertuzumab [HP] therapy). (Secondary Clinical Objective) IV. To evaluate
the association of estrogen receptor (ER) status in the untreated primary tumor with
pathologic response and with long-term survival outcomes (including RFS, EFS, IDFS, DDFS,
DRFS, RFI, OS, and breast cancer-specific survival). (Secondary Correlative Objective) V.
To evaluate the associations of detection of circulating tumor cells (CTCs) in the blood
at baseline with pCR. (Secondary Correlative Objective) VI. To evaluate the association
of detection of CTCs in the blood at baseline, after 3 weeks of THP, after 12 weeks of
THP (before surgery), after surgery before any additional therapy, and after completion
of HER2-targeted therapy with RFS in patients who achieve pCR or not. (Secondary
Correlative Objective)
EXPLORATORY OBJECTIVES:
I. To determine 3-year RFS, IDFS (invasive disease-free survival), DDFS (distant
disease-free survival), DRFS (distant relapse-free survival), RFI (recurrence-free
interval), OS (overall survival) and breast cancer-specific survival in patients who do
not achieve pCR (and by pretreatment clinical stage). (Exploratory Clinical Objective)
II. To determine the pathologic response to THP neoadjuvant therapy, as assessed by
residual cancer burden (RCB). (Exploratory Clinical Objective) III. To determine the
association between residual cancer burden (RCB) and all described standardized
definitions for efficacy end points (STEEP) criteria outcomes. (Exploratory Clinical
Objective) IV. To determine the false negative rate (FNR) of limited staging procedures
(defined as sentinel lymph node biopsy [SLNB] plus removal of clipped node) in patients
who undergo such procedures with a planned axillary lymph node dissection (ALND).
(Exploratory Clinical Objective) V. To determine axillary pCR rates as a function of the
burden of disease at presentation as determined on pre-treatment ultrasound (US) and the
axillary staging technique (SLNB plus ensuring removal of clipped node versus ALND).
(Exploratory Clinical Objective) VI. To evaluate the associations between plasma tumor
cell-free deoxyribonucleic acid (DNA) (cfDNA) tumor-specific mutations (baseline and
after therapy) with pathologic response and long-term outcomes (including RFS, EFS, IDFS,
DDFS, DRFS, RFI, OS, and breast cancer-specific survival). (Exploratory Correlative
Objective) VII. To evaluate the associations between tumor infiltrating lymphocytes
(TILs) and immune activation gene signatures in the baseline tumor with pathologic
response and long-term outcomes (including RFS, EFS, IDFS, DDFS, DRFS, RFI, OS and breast
cancer-specific survival). (Exploratory Correlative Objective) VIII. To determine the
frequency of change in intrinsic subtype between pretreatment tumor specimen and residual
disease at the time of surgery. (Exploratory Correlative Objective) IX. To evaluate the
associations between DNA copy number, DNA mutations, ribonucleic acid (RNA) expression
and protein expression in the baseline tumor and changes from baseline to post-THP
therapy with pathologic response and long-term outcomes (including RFS, EFS, IDFS, DDFS,
DRFS, RFI, OS, and breast cancer-specific survival). (Exploratory Correlative Objective)
OUTLINE:
PRE-OPERATIVE/NEOADJUVANT THERAPY: Patients receive either paclitaxel or nab-paclitaxel
intravenously (IV) on days 1, 8 and 15, or docetaxel IV on day 1 at the discretion of the
treating oncologist. Patients also receive trastuzumab IV on day 1 or days 1, 8, and 15,
and pertuzumab IV on day 1. Treatment repeats every 21 days for up to 4 cycles in the
absence of disease progression or unacceptable toxicity.
SURGERY: Within 42 days after last dose of neoadjuvant therapy, patients undergo standard
of care lumpectomy and/or mastectomy.
POST-OPERATIVE/ADJUVANT THERAPY: Patients are assigned to 1 of 2 arms.
ARM A: Patients with pCR after surgery receive trastuzumab and pertuzumab IV on day 1.
Treatment repeats every 21 days for up to 13 cycles in the absence of disease progression
or unacceptable toxicity. Patients may also undergo standard of care radiation therapy
and receive hormone therapy if appropriate.
ARM B: Patients with remaining tumor after surgery receive standard of care trastuzumab
emtansine for 14 doses in the absence of disease progression or unacceptable toxicity.
Patients may also receive additional standard of care chemotherapy, as well as hormone
therapy if appropriate.
After completion of study treatment, patients are followed up every 3 months for 2 years,
every 6 months for 2-5 years, then annually for 5-15 years from date of surgery.