| Polo-like kinase 1 (PLK-1) is a mitotic serine/threonine kinase and high-value cancer target. It is commonly upregulated in proliferative malignancies and supports G2/M progression, spindle formation, chromosome segregation, cytokinesis, DNA-damage recovery, and survival of genomically unstable tumor cells. Inhibition of PLK1 can induce mitotic arrest, apoptosis, and sensitization to chemotherapy or radiotherapy. Clinical development has been challenging due to toxicity and limited single-agent efficacy with earlier inhibitors, but newer agents such as onvansertib show renewed promise, particularly in RAS/KRAS-mutant metastatic colorectal cancer.
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