Incidence and Severity of Diarrhea in Patients With HER2 Positive Breast Cancer Treated With Trastuzumab and Neratinib

INCLUSION CRITERIA

• Age >= 18 years
• Histologically confirmed clinical or pathological stage 2 through stage 3c primary adenocarcinoma of the breast
• Documented human epidermal growth factor receptor 2 (HER2) overexpression or gene-amplified tumor by a validated approved method
• Patients can have hormone receptor (HR)+ or HR-negative disease
• Concurrent adjuvant endocrine therapy and bone-modifying agents is allowed
• Patients can be premenopausal or postmenopausal
• Completion of neoadjuvant or adjuvant chemotherapy
• Completion of adjuvant locoregional radiation, if indicated, is required prior to starting study treatment
• Histologically confirmed clinical or pathological stage 2 through stage 3c primary adenocarcinoma of the breast
• Documented HER2 overexpression or gene-amplified tumor by a validated approved method
• Patients can have hormone receptor (HR)+ or HR-negative disease
• Concurrent adjuvant endocrine therapy and bone-modifying agents is allowed
• Patients can be premenopausal or postmenopausal
• Completion of neoadjuvant or adjuvant chemotherapy
• Completion of adjuvant locoregional radiation, if indicated, is required prior to starting study treatment
• At the time of study enrollment, patients can still be receiving adjuvant trastuzumab monotherapy or be within 2 years of completing adjuvant trastuzumab +/- pertuzumab maintenance, or adjuvant T-DM1.
• Patients who are within 2 years of completing trastuzumab +/- pertuzumab or T-DM1 will receive neratinib monotherapy (and not neratinib + trastuzumab)
• Adjuvant T-DM1 is the standard of care for patients who have residual disease after neoadjuvant chemotherapy. Patients with residual disease after neoadjuvant chemotherapy should receive T-DM1 before enrolling on the study. If not, the option of T-DM1 should be discussed with the patient
• Clinically no evidence of metastatic disease at the time of study entry. Patients with fully resected locoregional recurrence with no evidence of disease are eligible
• Left ventricular ejection fraction (LVEF) >= 50% measured by multiple-gated acquisition scan (MUGA) or echocardiogram (ECHO)
• Eastern Cooperative Oncology Group (ECOG) status of 0 to 1
• Negative beta-human chorionic gonadotropin (hCG) pregnancy test for premenopausal women of reproductive capacity (those who are biologically capable of having children) and for women less than 12 months after menopause; (women are considered postmenopausal if they are >= 12 months without menses, in the absence of endocrine or anti-endocrine therapies)
• Trastuzumab can cause embryo-fetal harm when administered during pregnancy and the effects of neratinib on the developing human fetus are unknown. Women of child-bearing potential must agree and commit to use of a highly effective double-barrier method of contraception (e.g., a combination of male condom with an intravaginal device such as the cervical cap, diaphragm, or vaginal sponge with spermicide) or a non-hormonal method, from the signing of informed consent until 28 days after the last dose of neratinib and 7 months after the last dose of trastuzumab, or consent to total sexual abstinence (abstinence must occur from randomization and continue for 28 days after the last dose of neratinib and 7 months after the last dose of trastuzumab). Men without confirmed vasectomy must agree and commit to use a barrier method of contraception while on treatment and for 3 months after the last dose of investigational products, or consent to total sexual abstinence (abstinence must occur from randomization and continue for 3 months after the last dose of study medication)
• Recovery (i.e., to grade 1 or baseline) from all clinically significant adverse event (AE)s related to prior therapies (excluding alopecia, neuropathy, and nail changes)
• Provide written, informed consent to participate in the study and follow the study procedures

EXCLUSION CRITERIA

• Clinical or radiologic evidence of metastatic disease prior to or at