Synergistic anticancer effects of CFI-400945 with radiotherapy observed in preclinical models of lung [75] (Table 2) and breast cancers [103, 115, 138] provide an opportunity to develop new multimodality treatment approaches with PLK4 inhibition and radiotherapy to augment the anticancer efficacy of the latter, while providing potential advantages of the systemic treatment through the PLK4 inhibitor. Here, PLK4 is linked to breast cancer.