Maria Rossing

Implementing MyChoice® CDx HRD testing for the Nordics: lessons from 2021 to 2023

Background: Assessment of homologous recombinant deficient (HRD) phenotypes is key for managing Poly (ADP-ribose) polymerase inhibitor (PARPi) treatment. To accommodate the need for a validated HRD platform and enhance targeted treatment of ovarian cancer patients, a Nordic core facility for the myChoice® CDx platform was established in Denmark. Materials and methods: Comparative calculations and statistics are based on information from test requisitions and results (Genome Instability Score [GIS], BRCA status and combined HRD status) obtained from ovarian and breast cancer samples submitted for HRD-testing by myChoice® CDx through the Nordic core facility in the 2-year period. Results: Copenhagen University Hospital received 1,948 requisitions during the 2-year period. Conclusive results were obtained in 89% of the tests, while 7% were inconclusive due to the lack of GIS and 4% were not able to be analysed. Comparing the conclusive HRD status results across countries, Sweden had the highest percentage of HRD positives (38%) compared to Denmark, Norway, and Finland (28–32%). Interpretation: The myChoice® CDx Nordic core facility has been well received among the Nordic countries and provides new insights on the influence of national guidelines on HRD testing. Overall, we experienced an efficient turnaround time and a high fraction of conclusive results. Interestingly, prior somatic BRCA testing is redundant when assessing HRD status through myChoice® CDx test since somatic BRCA screening is already a significant component of the myChoice® CDx test. Thus, it should be considered to omit prior somatic BRCA testing to ensure a rationalised HRD diagnostic flow optimised for clinical use.

Combining Homologous Recombination-Deficient Testing and Functional RAD51 Analysis Enhances the Prediction of Poly(ADP-Ribose) Polymerase Inhibitor Sensitivity

PURPOSE To meet the urgent need for accessible homologous recombination-deficient (HRD) test options, we validated a laboratory-developed test (LDT) and a functional RAD51 assay to assess patients with ovarian cancer and predict the clinical benefit of poly(ADP-ribose) polymerase inhibitor therapy. METHODS Optimization of the LDT cutoff and validation on the basis of samples from 91 patients enrolled in the ENGOT-ov24/NSGO-AVANOVA1&2 trial (ClinicalTrials.gov identifier: NCT02354131 ), previously subjected to commercial CDx HRD testing (CDx). RAD51 foci analysis was performed and tumors with ≥five foci/nucleus were classified as RAD51-positive (homologous recombination-proficient). RESULTS The optimal LDT cutoff is 54. Comparing CDx genome instability score and LDT HRD scores show a Spearman's correlation of rho = 0.764 ( P < .0001). Cross-tabulation analysis shows that the sensitivity of the LDT HRD score is 86% and of the LDT HRD status is 91.8% (Fisher's exact test P < .001). Survival analysis on progression-free survival (PFS) of LDT-assessed patients show a Cox regression P < .05. RAD51 assays show a correlation between low RAD51 foci detection (<20% RAD51+ cells) and significantly prolonged PFS ( P < .001). CONCLUSION The robust concordance between the open standard LDT and the CDx, especially the correlation with PFS, warrants future validation and implementation of the open standard LDT for HRD testing in diagnostic settings.

Beyond HRD Status: Unraveling Genetic Variants Impacting PARP Inhibitor Sensitivity in Advanced Ovarian Cancer

Abstract The management of advanced epithelial ovarian cancer (AOC) has undergone significant advancements with the emergence of molecular diagnostics, particularly in predicting responses to PARP inhibitors (PARPi) based on homologous recombination deficiency (HRD) status. However, understanding sensitivity and resistance beyond HRD status remains elusive. This study aims to explore molecular factors that may elucidate why HRD status does not consistently predict PARPi sensitivity. Therefore, we conducted a post hoc translational analysis of formalin-fixed paraffin-embedded tumor samples from the ENGOT-ov24/NSGO-AVANOVA part 1 and 2 trial (NCT02354131), focusing on alterations pertaining radiologic response and progression-free survival (PFS). DNA sequencing was performed using the TruSight Oncology 500 HT gene panel, with variants classified according to recent guidelines. HRD status had been assessed by Myriad MyChoice CDx. We identified, among 92 patients in the ENGOT-ov24/NSGO-AVANOVA part 1 and 2 trial, 151 pathogenic or likely pathogenic variants across 81 samples. PARPi-sensitizing variants were found in two out of 10 HRD-negative samples from patients with clinical benefit (PFS ≥12 months), whereas three out of 10 HRD-positive samples from patients having no benefit (PFS ≤6 months) harbored variants associated with PARPi resistance. Additionally, analysis of BRCA1 variants revealed that truncating variants in exon 11 correlated with clinical benefit when niraparib was combined with bevacizumab. Conclusively, our findings highlight the complexity of PARPi response in AOC and underscore the importance of exploring somatic variants beyond HRD status. Further investigation into exon 11 variants of BRCA1 and the potential of combination treatment is warranted. Significance: The irregular response to PARPi in HRD-positive and -negative tumors highlights the need for identifying additional biomarkers. This study explores the mutational landscape beyond HRD status in AOC, ultimately advancing precision oncology in future clinical practice.

Niraparib Versus Niraparib-bevacizumab Combination in Women With Platinum-sensitive Epithelial Ovarian Cancer

Part 1 (Phase 1): safety and tolerability of bevacizumab-Niraparib combination Part 2 (Randomized Phase 2): to compare Progression-Free Survival (PFS) PARP inhibitors are active as monotherapy to treat patients with recurrent ovarian cancer; the strongest activity being observed in the platinum sensitive, gBRCAmut subgroup as well as in gBRCAwt, HRD population but also in HRD negative disease. In the same population there is level one evidence that bevacizumab is beneficial. And a phase two randomized study has indicated that combination of a PARP inhibitor with anti-angiogenic drug is superior to PARP inhibitor alone. The question is: Is niraparib combined with bevacizumab superior to niraparib? The comparison of tolerability and efficacy of niraparib-bevacizumab combination against niraparib.