Recent studies have shown that inhibition of kinases related to cell cycle check points, including checkpoint kinase 1 (CHK1), polo-like kinase 1 (PLK1), or aurora kinase A or B, exhibits synthetic lethality in combination with RB deficiency in triple-negative breast cancer (TNBC) or SCLC [19,20]. Here, PLK1 is linked to triple-negative breast carcinoma.