Induction of HRD in cancers by altering the tumour microenvironment through hypoxia (Chan et al, 2010) or by combining PARPis with agents that might downregulate HRR, such as VEGF inhibitors (Lui et al, 2014), might render HRR-competent cells sensitive to PARP inhibition. The gene discussed is PARP1; the disease is cancer.