Patient description: The patient is a 42 year-old postmenopausal woman who had a screening sonogram which revealed an abnormality in the right breast. She had no palpable masses on breast exam. Core biopsy was done and revealed a 1.8 cm infiltrating ductal breast carcinoma in the left upper outer quadrant. Lumpectomy was done and the surgical margins were clear. The tumor was HER2-positive and ER/PR negative. Axillary sampling revealed 1 positive lymph node out of 12 sampled. CXR was unremarkable. She is using “well women” multivitamins daily and no other medication. She smokes frequently and consumes alcohol occasionally. She is in a relation with only one partner and has a history of 3 pregnancies and live births. She breastfed all three children.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Breast Cancer years or older Eastern Cooperative Oncology Group (ECOG) performance status 0,1 AJCC stage I III non-inflammatory, HER2-positive (according to ASCO-CAP guidelines 5) breast cancer Completed neoadjuvant therapy with an approved regimen that includes trastuzumab and at least four cycles (12 weeks) of taxane-containing chemotherapy and underwent surgery with final pathology showing evidence of residual disease in the breast or axilla (residual ductal carcinoma in situ or microinvasive disease not eligible) or underwent surgery as a first intervention and was found to be pathologically node-positive: ≥ 4 positive lymph nodes (pN2 or pN3) regardless of hormone receptor status or 1-3 positive lymph nodes (pN1) if hormone receptor negative. Patients with micrometastases (pN1mi) are not eligible Completed an approved regimen of neoadjuvant or adjuvant therapy with an approved regimen that includes trastuzumab and at least four cycles (12 weeks) of taxane-containing chemotherapy with plan for completion of one year of trastuzumab therapy Completed appropriate surgical therapy to 1. Total mastectomy and axillary staging with sentinel lymph node dissection or axillary lymph node dissection (level I/II). Patients with a positive sentinel lymph node must have undergone a completion axillary lymph node dissection. 2. Breast conserving surgery (BCS) and axillary staging with sentinel lymph node dissection or axillary lymph node dissection. Patients undergoing surgery as a first intervention with a positive sentinel lymph node must have undergone a completion axillary dissection level I/II unless they had clinically node negative T1-T2 tumors and fewer than 3 involved lymph nodes. Patients receiving neoadjuvant chemotherapy that have a positive sentinel lymph node must have undergone a completion axillary lymph node dissection. 3. Completed or receiving appropriate radiation therapy if indicated: For patients undergoing total mastectomy surgery as a first intervention, post-mastectomy radiation to the chest wall, infraclavicular and supraclavicular areas is required for patients with ≥ 4 positive lymph nodes. Radiation to the internal mammary lymph nodes is not required per protocol but is allowed at the discretion of the patient's treating radiation oncologist. For patients with 1-3 positive lymph nodes, post-mastectomy radiation to the chest wall, infraclavicular, supraclavicular, and internal mammary areas is not required per protocol but is allowed at the discretion of the patient's treating radiation oncologist For patients undergoing breast conserving surgery (BCS) as a first intervention, whole breast irradiation with or without a boost, and radiation to the infraclavicular and supraclavicular areas is required for patients with ≥ 4 positive lymph nodes. Radiation to the internal mammary lymph nodes is not required but is allowed at the discretion of the patient's treating radiation oncologist. For patients with 1-3 positive lymph nodes, whole breast irradiation with or without a boost is required. Radiation to the infraclavicular, supraclavicular, and internal mammary areas is not required per protocol but is allowed at the discretion of the patient's treating medical oncologist For patient's undergoing mastectomy after neoadjuvant chemotherapy post-mastectomy radiation to the chest wall, infraclavicular and supraclavicular areas is required for patients presenting with clinical N2 or N3 disease or with ≥ 4 positive lymph nodes identified pathologically at the time of surgery. Radiation to the internal mammary lymph nodes is not required per protocol but is allowed at the discretion of the patient's treating radiation oncologist. For patients with 0-3 positive lymph nodes identified pathologically, post-mastectomy radiation to the chest wall, infraclavicular, supraclavicular and internal mammary areas is not required per protocol but is allowed at the discretion of the patient's treating radiation oncologist For patient's undergoing BCS after neoadjuvant chemotherapy, whole breast irradiation with or without a boost is required. For patients with clinical N2 or N3 disease or with ≥ 4 positive lymph nodes identified pathologically at the time of surgery, radiation to the infraclavicular and supraclavicular areas is required. Radiation to the internal mammary lymph nodes is not required per protocol but is allowed at the discretion of the patient's treating radiation oncologist. For patients with 0-3 positive lymph nodes identified pathologically, radiation to the infraclavicular, supraclavicular and internal mammary areas is not required per protocol but is allowed at the discretion of the patient's treating radiation oncologist  AJCC Stage IV breast cancer NYHA stage 3 or 4 congestive heart failure Immune deficiency disease or known history of HIV, HBV, HCV Receiving immunosuppressive therapy including chronic steroids, methotrexate, or other known immunosuppressive agents Pregnancy (assessed by urine HCG) Breast feeding Any active autoimmune disease requiring treatment, with the exception of vitiligo Active pulmonary disease requiring medication to multiple inhalers (>3 inhalers including one containing steroids) Involved in other experimental protocols except with permission of other PI