**Study Summary:** This clinical study is for people with a certain kind of breast cancer called *HER2/neu positive*. The study will test a new treatment called GLSI-100 to see if it works well and is safe. The treatment involves getting injections under the skin, called intradermal injections, over several months. Participants will first get 6 injections in the first 6 months and then 5 more spread out every 6 months. There will be two groups: one with people who have a specific protein called *HLA-A02* and one without. To join, participants must have finished their usual cancer treatments and meet specific health conditions. **Key Points:** - Participants will receive a series of 11 injections over several months. - You must have completed certain standard cancer treatments to join. - The study is for patients with specific types of breast cancer and health conditions. People interested should consider their health status, the time commitment, and the study's requirements before deciding to join.