BRCA1 and neoplasm: PARPi exploit the mechanism of ‘synthetic lethality’, that is loss of function in two genes causes cell death as opposed to a non-lethal effect of functional loss of one of the genes, to target tumours with defective DNA repair mechanisms, such as aberrant homologous recombination (HR) repair due to loss of BRCA1 and 2 gene function through the presence of mutations [25].