Pri mary 1. Evaluate whether HER2 peptide -based booster vaccines can enhance HER2 -specific immunity. 2. Evaluate whether HER2 peptide -based booster vaccines induce increase in memory T -cell populations in patients’ peripheral blood. 3. Evaluate whether HER2 pe ptide -based booster vaccinations demonstrate acute inflammatory response in lymph nodes draining the vaccine site, and in tumor metastasis, by FDG -PET. 6304p Protocol 118 04/06/2016 11 B. Secondary 1. Evaluate the safety of HER2 peptide -based booster vaccines in patients who previously received the HER2 peptide -based vaccines. 4.