RecruitingDrug trialHER2 FPBMC in Patients With Metastatic Breast and Prostate Cancer (AM006)The purpose of this study is to understand the safety and estimate the efficacy of anti-CD3 x anti-HER2 bispecific antibody (HER2Bi) armed fresh peripheral blood mononuclear cells (HER2 FPBMC) for patients with metastatic breast or prostate cancer. Participants receive 5 weekly doses of CD33 FPBMC by intravenous infusion followed by 4 infusions every other week.