BRCA1, BRCA2 and HRD Score
The Homologous Recombination Repair (HRR) pathway plays an important role in the repair of double-strand breaks, which is a major cause of cancer development. It has been demonstrated that loss of function of HRR genes, Homologous Recombination Deficiency (HRD) is the inability to repair double strand breaks and will cause a higher risk of developing cancer[1-5]. Patients with HRD showed higher responses to poly ADP ribose polymerase inhibitors (PARPi) and platinum-containing therapies[6-7]. HRD Score testing and BRCA1/2 mutations testing have been approved for patient selection for PARPi therapy.
The AmoyDx® HRD Focus Panel (Reversible Terminator Sequencing) is a next generation sequencing-based in vitro diagnostic test that determines a patient's HRD status by detecting SNVs and InDels in whole coding regions and intron/exon boundaries of the BRCA1 and BRCA2 genes, and determining a genomic scar score (GSS) using DNA isolated from neutral formalin-fixed paraffin-embedded (FFPE) tissue samples.
The kit is intended to be used by trained professionals in a laboratory environment.
Principles of the Procedure
The test kit is based on the Halo-shape ANnealing and Defer-Ligation Enrichment (HANDLE) system technology which is an improved Molecular Inversion Probe (MIP) technology to capture the target gene region (Figure 1). The unique molecular identifier (UID) is introduced to both ends of each DNA fragment to trace back to original template for error correction. The library construction time of HANDLE system is 5 hours with 1 hour hands-on time. After quality control (QC), the prepared DNA libraries are sequenced on Illumina sequencing platforms to detect the BRCA1/2 gene mutations and HRD status.
Figure 1. Principle of library construction (HANDLE system)
The probe contains an extension arm and a ligation arm which are complementary to the target gene region. First, the extension arm and ligation arm are anchored to the target gene region, and the DNA is extended from the extension arm to the ligation arm using DNA polymerase. Next, the nicks are connected with the ligase to generate the circular products. The remaining linear probes, single-strand and double-strand nucleic acid are digested with the exonuclease. Finally, the universal PCR amplification is performed to enrich the target libraries.
1. Farmer H, Mccabe N, Lord CJ, Tutt A, Johnson DA, et al. (2005) Targeting the DNA repair defect in BRCA mutant cells as a therapeutic strategy. Nature 434: 917-921.
2. Walsh CS (2015) Two decades beyond BRCA1/2: Homologous recombination, hereditary cancer risk and a target for ovarian cancer therapy. Gynecol Oncol 137: 343-350.
3. Lord CJ, Ashworth A (2016) BRCAness revisited. Nat Rev Cancer 16: 110-120.
4. Nicholas Turner ATaAA (2004) Hallmarks of ‘BRCAness’ in sporadic cancers. PERSPECTIVES 4.
5. McCabe N, Turner NC, Lord CJ, Kluzek K, Bialkowska A, et al. (2006) Deficiency in the repair of DNA damage by homologous recombination and sensitivity to poly(ADP-ribose) polymerase inhibition. Cancer Res 66: 8109-8115.
6. Ray-Coquard I (2019) Olaparib plus Bevacizumab as First-Line Maintenance in Ovarian Cancer. N Engl J Med: 2416-2428.
7. KN M QUADRA: a phase 2, open-label single-arm study to evaluate niraparib in patients with relapsed ovarian cancer in 4th or later line of therapy: results from the BRCAmut subset. 2018 ESMO Congress: 944.
AmoyDx HANDLE HRD Focus Panel is available in the following size.
|Product Name||Size (test/kit)||Storage||Cat. No.|
|AmoyDx HRD Focus Panel||20T||-20℃||