However, because CDK4/6 inhibition is often insufficient to fully control the tumour progression, rationally developed doublet or triplet combination therapies of CDK4/6i are evaluated in various cancers, for instance with kinase inhibitors (e.g. MEK, PI3K, mTOR, EGFR inhibitors, ...) [21], genotoxic therapies [27, 28] and immunotherapies [21, 27, 29, 30]. This evidence concerns the gene CDK4 and cancer.