RecruitingPhase 1Biological interventionAdoptive T Cell Therapy Following HER2-Pulsed Dendritic Cell Vaccine & Pepinemab /Trastuzumab in Patients w/ Metastatic HER2+ Breast CancerThe purpose of this study is to test the safety of Adoptive T-Cell therapy following the Dendritic Cell (DC1) study vaccine given in combination with pepinemab added to standard of care therapy, trastuzumab to help people with HER2 positive breast cancer.