Introduction/Background Assessment of Homologous Recombination Deficiency (HRD) and BRCA mutational status in high-grade serous ovarian carcinoma (HGSOC) samples has become crucial for personalized medicine, guiding treatment decisions and predicting response to specific therapies, such as PARP inhibitors. While Myriad MyChoice® CDx HRD (M-HRD) is a widely adopted clinically validated reference method, it’s performed as a send-out test. We sought to assess the reliability and reproducibility of SOPHIA DDM(TM)Dx HRD Solution (SG-HRD) across different hospitals to consider its implementation as a decentralized solution in routine molecular diagnostics.

Methodology We included 24 HGSOC samples for analysis using SG-HRD in three different hospitals. Each hospital contributed with 8 samples previously tested with M-HRD or with SG-HRD in a send-out platform. The libraries of the 24 samples have been prepared and sequenced independently by the 3 hospitals. The samples underwent sequencing in two distinct runs on a NextSeq550 sequencing platform (Illumina). Sensitivity was assessed across all samples with confirmed variants, while specificity, accuracy, and precision were evaluated exclusively within characterized regions. Consistency was gauged for both inter-run and intra-run replicates.

Results All 24 samples resulted of good enough quality for SG-HRD and BRCA1/2 status assessment. HRD status by means of genomic integrity was 95.4%, 91%, and 90.4% concordant for each of the 3 centers. Lower concordance was observed in 2 HRD borderline samples. BRCA status concordance was 100% between the 3 centers. Intra-hospital replicability was confirmed as 100%. Overall, the comparison with previous analyses by M-HRD or previous results from SG-HRD send-out tests revealed no discrepancies, affirming the accuracy of the SOPHIA DDM(TM)Dx HRD Solution.

Conclusion This collaborative study concludes that SOPHiA HRD Solution provides reliable and consistent results across different hospitals and sequencing runs. These findings contribute to the growing body of evidence supporting the use of SG-HRD in clinical settings for genomic analysis.

Acknowledgements This study was funded by Astra Zeneca.

Gardenia Vargas Parra – Grants/research support: Roche. Participation in Astrazeneca sponsored speaker’s bureau.

Marta Sese Faustino – No conflicts

Eva Hernández-Illán- No conflicts

Laura Camacho - No conflicts

Rosa Somoza - No conflicts

Vanessa López - No conflicts

Cristina Teixido - Grants/research support: Novartis. Receipt of honoraria: MSD, Pfizer, Janssen Oncology, Roche Pharma, Astrazeneca. Participation in company sponsored speaker’s bureau: Astrazeneca, Novartis.

Pedro Jares – No conflicts

Javier Hernández Losa – Grants/research support: Lilly, Roche Pharma, Bayer. Receipt of honoraria: MSD. Lully, Pfizer, Owkin, Thermofisher, Janssen, Astellas.

Beatriz Bellosillo – Grants/research support: Astrazeneca, Thermofisher, Roche. Receipt of honoraria: Novartis, Thermofisher, Janssen. Participation in company sponsored speaker’s bureau: Astrazeneca, MSD, Novartis, Janssen, Merck-Serono, Roche, Thermofisher, Pfizer.