Homologous recombination deficiency test validation in patients with high-grade advanced ovarian cancer

TL;DR

This study validates a new test for homologous recombination deficiency in ovarian cancer patients, showing it performs well compared to an existing test.

Contribution

The study validates a new NGS-based HRD test for diagnostic use in Brazil.

Findings

The GS Focus HRD test showed high concordance (kappa: 0.8) with the reference MyChoice® HRD Plus CDx test.

The new test achieved 90% overall accuracy, sensitivity, and specificity in HRD classification.

All BRCA1/2 mutations detected by the reference test were also identified by the GS Focus HRD test.

Abstract

Along with BRCA mutation status, homologous recombination deficiency (HRD) testing is a prognostic and predictive biomarker for poly-ADP-ribose polymerase (PARP) inhibitor therapy indication in high-grade epithelial ovarian, fallopian tube, or peritoneal cancer. Approximately 50% of high-grade serous ovarian cancers exhibit HRD, even in the absence of germline or somatic BRCA1/2 loss-of-function mutations. In this scenario, access to a validated diagnostic HRD test can optimize treatment selection and increase the effectiveness of the intervention.

To technically validate an in-house next-generation sequencing (NGS)-based HRD test, QIAseq Custom Panel (QIAGEN), by comparing it with the reference assay, MyChoice CDx® Plus HRD (Myriad Genetics), which is used in routine care.

This is a prospective cohort study conducted at the Oncoclínicas Precision Medicine (OCPM) laboratory using samples from patients with advanced or relapsed platinum-sensitive ovarian cancer eligible for HRD testing in a diagnostic clinical setting at Oncoclínicas and Co. We assessed the performance of the in-house test (GS Focus HRD) using Cohen’s kappa statistic to measure agreement with the gold standard assay (MyChoice® HRD Plus CDx) in HRD status classification, along with other accuracy metrics.

In total, 41 samples were analyzed (20 HRD-positive, 19 HRD-negative, and 2 inconclusive results with the MyChoice® HRD Plus CDx assay). The GS Focus HRD test demonstrated high concordance for HRD status with the reference test (kappa: 0.8 and 95% CI: 0.60–0.98). Overall accuracy, sensitivity, and specificity were 90%. Six samples had BRCA1/2 mutations identified by the MyChoice® HRD Plus CDx, all of which were detected by the GS Focus HRD test.

In summary, the results demonstrate substantial agreement and high accuracy of the NGS-based GS Focus HRD test compared to MyChoice® HRD Plus CDx. Our in-house assay is eligible for diagnostic test approval and market access as per Brazilian regulations.

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