Comprehensive genomic profiling for homologous recombination deficiency guides PARP inhibitor therapy recommendations in ovarian cancer.

Abstract

Objective: To evaluate the technical performance and clinical integration of FoundationOne®CDx (F1CDx) for high-grade serous ovarian cancer (HGSOC), focusing on its role in guiding PARP inhibitor (PARPi) therapy recommendations in a tertiary oncology center.

Methods: We conducted a retrospective analysis of 178 F1CDx tests performed on 168 HGSOC patients with unknown BRCA mutation status between January 2019 and August 2024. Molecular findings, including BRCA1/2 mutations, homologous recombination deficiency (HRD) status, loss of heterozygosity (LOH) scores, and HRR-related gene alterations, were correlated with tumor board recommendations and decisions for PARPi therapy. Laboratory turnaround time (TAT), assay performance, and integration into clinical workflows were assessed.

Results: The F1CDx assay successfully generated comprehensive molecular profiles in 174 samples, with minimal limitations due to computational tumor content or inconclusive HRD readout. BRCA1/2 mutations were detected in 13.1% of patients, and 39.5% of tumors were HRD-positive (LOH ≥16%). In the internal cohort, 81.8% of patients received PARPi therapy recommendations, all directly informed by F1CDx results. PARPi selection differed by HRD status, with niraparib favored in HR-proficient and olaparib in HRD-positive tumors. The mean laboratory TAT was 8.4 days (standard deviation ±3.8), with 92.2% of tests completed within 14 days. No additional profiling was required for PARPi therapy recommendation, and no incidental findings beyond the scope of HRD testing were detected.

Conclusion: Molecular profiling with F1CDx proved to be a technically feasible, clinically impactful, and time-efficient assay, demonstrating its value in supporting molecular-guided PARPi therapy recommendations in the routine care of HGSOC patients.