Homologous recombination deficiency in ovarian cancer: Global expert consensus on testing and a comparison of companion diagnostics

Background: Poly (ADP ribose) polymerase inhibitors (PARPis) are a treatment option for patients with advanced high-grade serous or endometrioid ovarian carcinoma (OC). Recent guidelines have clarified how homologous recombination deficiency (HRD) may influence treatment decision-making in this setting. As a result, numerous companion diagnostic assays (CDx) have been developed to identify HRD. However, the optimal HRD testing strategy is an area of debate. Moreover, recently published clinical and translational data may impact how HRD status may be used to identify patients likely to benefit from PARPi use. We aimed to extensively compare available HRD CDx and establish a worldwide expert consensus on HRD testing in primary and recurrent OC. Methods: A group of 99 global experts from 31 different countries was formed. Using a modified Delphi process, the experts aimed to establish consensus statements based on a systematic literature search and CDx information sought from investigators, companies and/or publications. Results: Technical information, including analytical and clinical validation, were obtained from 14 of 15 available HRD CDx (7 academic; 7 commercial). Consensus was reached on 36 statements encompassing the following topics: 1) the predictive impact of HRD status on PARPi use in primary and recurrent OC; 2) analytical and clinical validation requirements of HRD CDx; 3) resource-stratified HRD testing; and 4) how future CDx may include additional approaches to help address unmet testing needs. Conclusion: This manuscript provides detailed information on currently available HRD CDx and up-to-date guidance from global experts on HRD testing in patients with primary and recurrent OC.