Since the repair of these lesions requires an intact homologous recombination (HR) pathway, HR-deficient cancers (e.g., due to dysfunctional BRCA1/2) amass chromosomal aberrations resulting in cell death by mitotic catastrophe after PARPi treatment (Lupo and Trusolino, 2014; Pommier et al, 2016; Rose et al, 2020). Here, BRCA1 is linked to cancer.