Anticancer Effects of Radiation Therapy Combined with Polo-Like Kinase 4 (PLK4) Inhibitor CFI-400945 in Triple Negative Breast Cancer

Abstract Development of novel multimodality radiotherapy treatments in metastatic breast cancer, especially in the most aggressive triple negative (TNBC) subtype, is of significant clinical interest. Here we show that a novel inhibitor of Polo-Like Kinase 4 (PLK4), CFI-400945, in combination with radiation, exhibits a synergistic anti-cancer effect in TNBC cell lines and patient-derived organoids in vitro and leads to a significant increase in survival to tumor endpoint in xenograft models in vivo, compared to control or single-agent treatment. Further preclinical and proof-of-concept clinical studies are warranted to characterize molecular mechanisms of action of this combination and its potential applications in clinical practice.