HR and breast cancer: Patient‐derived organoid (PDO) models have proven reliable in recapitulating tumor heterogeneity and architecture in breast cancer, emerging as promising preclinical models for predicting therapeutic response.[19] Thus, a total of 12 organoids derived from HR+/HER2− breast tumors were developed for drug sensitivity assay with palbociclib or fulvestrant (Figure S4A,B, Supporting Information).