This remarkable sensitivity of MPM cell lines to CDK4/6 inhibition contrasts with a more partial response and/or rapidly developing resistance (adaptation) observed in other cancers such as oestrogen receptor‐positive breast cancer [80], pancreatic ductal adenocarcinoma (PDAC) [89, 90], colorectal cancer [91] and anaplastic thyroid cancer [92]. The gene discussed is CDK4; the disease is breast cancer.