This was recently demonstrated by Montaudon and colleagues in which the size of an ER-positive BrCa patient’s PT and bone metastasis-derived PDX (patient-derived xenograft) rapidly shrunk after treatment with volasertib, an inhibitor of the PLK1 (which along with AURKA and CDK1 were upregulated in the PDX) [77]. The gene discussed is CDK1; the disease is invasive breast carcinoma.