CDH1 and neoplasm: Immunohistochemical staining of PDOs and matched primary tumours (Fig. 5) revealed a reduction of E-cadherin levels in PDO KCL566 (IC-NST with acquired CDH1 truncating mutation in CSF cfDNA and BCLM PDO), commensurate with the reduced CDH1 expression compared to its primary tumour (RNAseq; Fig. 6c), the lack of PDO CDH1 expression detected by RTqPCR (Fig. 6d) and the lack of E-cadherin staining when grown as patient-derived xenografts (PDXs; see later).