Homologous Recombination Deficiency Testing to Inform Patient Decisions About Niraparib Maintenance Therapy for High-Grade Serous or Endometrioid Epithelial Ovarian Cancer: A Health Technology Assessment.

Background: Ovarian cancer affects the cells of the ovaries, and epithelial cancer is the most common type of malignant ovarian cancer. The homologous recombination repair pathway enables error-free repair of DNA double-strand breaks. Damage of key genes associated with this pathway leads to homologous recombination deficiency (HRD), which results in unrepaired DNA and can lead to cancer. Tumours with HRD are believed to be sensitive to treatment with poly-adenosine diphosphate (ADP)-ribose polymerase (PARP) inhibitors, such as niraparib. We conducted a health technology assessment to evaluate the clinical utility and cost-effectiveness of HRD testing to inform patient decisions about the use of niraparib maintenance therapy for patients with high-grade serous or endometrioid epithelial ovarian cancer. We also evaluated the efficacy and safety of niraparib maintenance therapy in patients with HRD or homologous recombination proficiency (HRP), the cost-effectiveness of HRD testing, the budget impact of publicly funding HRD testing, and patient preferences and values. Methods: We performed a systematic literature search of the clinical evidence. We assessed the risk of bias of each included study using the Cochrane risk-of-bias tool for randomized trials version 2, and the quality of the body of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria. We performed a systematic economic literature search and conducted a cost-utility analysis with a 5-year time horizon from a public payer perspective. We also analyzed the budget impact of publicly funding HRD testing in people with ovarian cancer in Ontario. We performed a literature search for quantitative evidence of patient and provider preferences with respect to HRD testing and maintenance therapy with PARP inhibitors. To contextualize the potential value of HRD testing, we spoke with people with ovarian cancer. Results: The clinical evidence review included two studies in high-grade epithelial ovarian cancer (one in patients with newly diagnosed advanced cases and one in patients with recurrent cancer). The studies evaluated niraparib maintenance therapy compared with no maintenance therapy and used HRD testing to group patients according to HRD status. Compared to placebo, niraparib maintenance therapy improved progression-free survival in patients with newly diagnosed and recurrent ovarian cancer, and in tumours with HRD or HRP (GRADE: High), but the studies did not compare the results between the HRD and HRP groups. The frequency of adverse events was higher in the niraparib group. We identified no studies that evaluated the clinical utility of HRD testing.We conducted a primary economic evaluation to evaluate the cost-effectiveness of HRD testing for people with newly diagnosed ovarian cancer in an Ontario setting. Our analysis used a 5-year time horizon. HRD testing (for all eligible people or only for people with Conclusions: In patients with newly diagnosed (advanced) or recurrent high-grade serous or endometrioid ovarian cancer, niraparib maintenance therapy improved progression-free survival compared with no maintenance therapy in tumours with HRD or HRP (GRADE: High). Because we identified no studies on the clinical utility of HRD testing, we cannot comment on how it would affect patient decisions and clinical outcomes.Over a 5-year time horizon, HRD testing for people with