For several years, a major obstacle in the systemic treatment of ovarian cancer 
has been the lack of a therapeutic strategy tailored to specific biomarkers 
present in the individual patient's tumour. However, considerable progress has 
been made recently through the development of drugs targeting cells deficient in 
the key mechanism of double-strand DNA repair, known as homologous recombination 
(HRD). These drugs, inhibitors of the enzyme poly (ADP) ribose polymerase 
(PARP), selectively kill HRD cells through a process known as tumour-selective 
synthetic lethality. Olaparib is the first such agent, now approved for the 
treatment of ovarian cancer associated with mutations in the BRCA 1/2 genes, 
since these are characterised by cells with HRD. Importantly, another group of 
patients with tumours bearing a similar repair deficiency but without BRCA 
mutations may also be susceptible to PARP inhibition and efforts to develop an 
HRD assay are therefore a priority so that these patients can be identified as 
PARPi candidates. In addition, combination strategies are an area of intense 
research; these include combinations with antiangiogenic agents and with 
inhibitors of the P13K/AKT pathway and others are likely to merit assessment 
since resistance to PARP inhibitors will certainly emerge as the next challenge. 
While olaparib is the first PARP inhibitor to receive approval for ovarian 
cancer treatment, others including rucaparib and niraparib are clearly effective 
in this disease and, within the next year or two, the results of ongoing 
randomised trials will clarify their respective roles. PARP inhibitors are 
generally well tolerated; regulatory approval at present supports their use as a 
maintenance therapy (in Europe) and as treatment for advanced recurrent disease 
(in the United States), but it is likely that these indications will extend as 
the results of ongoing trials become available. Ten years have elapsed between 
the first pre-clinical publications and the regulatory approval of PARP 
inhibitors and the next 10 years promise to be even more productive.