“…Human tumour organoids have been generated from colon (Sato et al , ; van de Wetering et al , ), pancreas (Boj et al , ; Huang et al , ), prostate (Gao et al , ; Drost et al , ), breast (Sachs et al , ), gastric (Nanki et al , ; Yan et al , ), lung (Sachs et al , ), oesophageal (Li et al , ), bladder (Lee et al , ; Mullenders et al , ), ovarian (Kopper et al , ), kidney (Schutgens et al , ) and liver (Broutier et al , ; Li et al , ) tumour tissue (Fig ). An important feature of a number of these PDTOs is that they genetically and phenotypically mirror the tumour epithelium, including its intra‐tumour heterogeneity (Huang et al , ; van de Wetering et al , ; Nanki et al , ; Sachs et al , ; Yan et al , ). In a recent study, Roerink and colleagues characterized organoids derived from single cells from several colorectal cancers (CRC) and showed extensive mutational diversification as well as differences in responses to anti‐cancer drugs between even closely related cells of the same tumour (Roerink et al , ).…”