Screening of 160 drugs, including FDA-approved chemotherapeutics and targeted compounds, showed comparable drug responses between tumoroids and PDTX models.114 Moreover, to comprehensively encompass the diversity of breast cancer, a biobank comprising over 100 organoids derived from both primary and metastatic breast cancers has been established.115 These tumoroids faithfully mimic the typical morphology and histopathology of breast cancer while largely conserving the hormone receptor and Her2 status of the parental tumors. Here, ERBB2 is linked to breast cancer.