The first human study with [64Cu]Cu-DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) (64Cu)-trastuzumab was conducted by Tamura et al. in a cohort of six patients with primary or metastatic HER2-positive breast cancer [37]. This evidence concerns the gene ERBB2 and breast cancer.