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Functional RECAP (REpair CAPacity) assay identifies homologous recombination deficiency undetected by DNA-based BRCAness tests.

ABSTRACT: Germline BRCA1/2 mutation status is predictive for response to Poly-[ADP-Ribose]-Polymerase (PARP) inhibitors in breast cancer (BC) patients. However, non-germline BRCA1/2 mutated and homologous recombination repair deficient (HRD) tumors are likely also PARP-inhibitor sensitive. Clinical validity and utility of various HRD biomarkers are under investigation. The REpair CAPacity (RECAP) test is a functional method to select HRD tumors based on their inability to form RAD51 foci. We investigated whether this functional test defines a similar group of HRD tumors as DNA-based tests. An HRD enriched cohort (n = 71; 52 primary and 19 metastatic BCs) selected based on the RECAP test (26 RECAP-HRD; 37%), was subjected to DNA-based HRD tests (i.e., Classifier of HOmologous Recombination Deficiency (CHORD) and BRCA1/2-like classifier). Whole genome sequencing (WGS) was carried out for 38 primary and 19 metastatic BCs. The RECAP test identified all bi-allelic BRCA deficient samples (n = 15) in this cohort. RECAP status partially correlated with DNA-based HRD test outcomes (70% concordance for both RECAP-CHORD and RECAP-BRCA1/2-like classifier). RECAP selected additional samples unable to form RAD51 foci, suggesting that this functional assay identified deficiencies in other DNA repair genes, which could also result in PARP-inhibitor sensitivity. Direct comparison of these HRD tests in clinical trials will be required to evaluate the optimal predictive test for clinical decision making.

SUBMITTER: Meijer TG

PROVIDER: S-EPMC9232391 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature

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Functional RECAP (REpair CAPacity) assay identifies homologous recombination deficiency undetected by DNA-based BRCAness tests.

Meijer Titia G TG Nguyen Luan L Van Hoeck Arne A Sieuwerts Anieta M AM Verkaik Nicole S NS Ladan Marjolijn M MM Ruigrok-Ritstier Kirsten K van Deurzen Carolien H M CHM van de Werken Harmen J G HJG Lips Esther H EH Linn Sabine C SC Memari Yasin Y Davies Helen H Nik-Zainal Serena S Kanaar Roland R Martens John W M JWM Cuppen Edwin E Jager Agnes A van Gent Dik C DC

Oncogene 20220603 26

Germline BRCA1/2 mutation status is predictive for response to Poly-[ADP-Ribose]-Polymerase (PARP) inhibitors in breast cancer (BC) patients. However, non-germline BRCA1/2 mutated and homologous recombination repair deficient (HRD) tumors are likely also PARP-inhibitor sensitive. Clinical validity and utility of various HRD biomarkers are under investigation. The REpair CAPacity (RECAP) test is a functional method to select HRD tumors based on their inability to form RAD51 foci. We investigated ...[more]

PMID: 35662281

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Project description:IntroductionTesting for homologous recombination deficiency (HRD) as a biomarker in relation to poly (ADP-ribose) polymerase inhibitor (PARPi) treatment in ovarian cancer is done by sequencing of the BRCA1/2 genes and/or by assessing a genomic instability signature. Here we present data obtained with two different methods for genomic instability testing: the Oncomine™ Comprehensive Assay Plus (OCA Plus) NGS panel and the OncoScan CNV assay.MethodsThe retrospective analytical study included 80 ovarian cancer samples of patients previously referred to clinical Myriad testing (reference cohort), and 50 ovarian cancer samples from patients collected as part of the Pelvic Mass study. OCA Plus NGS libraries were sequenced with the Ion S5™XL Sequencer and analyzed with the Ion Reporter™ Software v5.20 for calculation of the genomic instability metric (GIM). In addition, all samples were tested with the OncoScan CNV FFPE Assay and analyzed with a previously published R-algorithm for generation of an in-house genomic instability score (in-house GIS).ResultsThe OCA Plus assay had a concordance to the reference of 89% on samples with a tumor fraction ≥ 30% (auto-calculated or via molecular estimation). A total of 15 samples in the reference cohort had a calculated tumor fraction < 30% in the OCA Plus assay. In these, the concordance to reference was only 60%. For the OncoScan CNV in-house GIS a local cutoff point of ≥ 50 was calculated. This gave a concordance to the reference of 85%, with 91% of the samples in the reference cohort passing quality control (QC) on tumor fraction. Both assays had a high sensitivity for the detection of genomic instability in samples with pathogenic or likely pathogenic BRCA1/2 mutations, with 12/13 being GIM positive (OCA Plus assay) and 13/13 being in-house GIS positive (OncoScan CNV assay).ConclusionsThe OCA Plus assay and the OncoScan CNV assay show a high but not complete concordance to reference standard homologous recombination deficiency (HRD) detection. The main reason for QC failure or non-concordance in our study was a low tumor fraction estimated in the assay, despite the selection of material by a pathologist with an inclusion criterion of > 30% tumor. QC steps should include careful tumor content evaluation, and results on samples with < 30% tumor should not be reported.

Dataset Information

Functional RECAP (REpair CAPacity) assay identifies homologous recombination deficiency undetected by DNA-based BRCAness tests.

Publications

Functional RECAP (REpair CAPacity) assay identifies homologous recombination deficiency undetected by DNA-based BRCAness tests.

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