Two models, namely BCO17 and IDC031, were validated by immunohistochemical staining showing the absence of signal for ER, PR and HER2, as well as the presence of the proliferation marker Ki67, as observed in the matching primary tumor tissues (Fig. 4D and Additional file 1: Fig. S4A), thereby confirming that our TNBC organoid models recapitulate the histological pattern of the tissue of origin. Here, ESR1 is linked to neoplasm.