Specifically, palbociclib has been proposed for use in metastatic prostate cancers in combination with several agents that target androgen biosynthesis (ClinicalTrials.gov identifier: NCT02059213), whereas ribociclib has been proposed for use in combination with enzalutamide in metastatic CRPCs that express wild-type RB (ClinicalTrials.gov identifier: NCT02555189). Here, RB1 is linked to metastatic prostate carcinoma.