# Homologous recombination deficiency (HRD)

Source: https://onco.cc/terms/hrd/  
OnCo record `hrd` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A tumour that cannot properly repair double-strand DNA breaks, usually because of BRCA or related gene loss.

## Summary

Homologous recombination deficiency (HRD) describes a tumour that cannot properly repair double-strand DNA breaks, usually because BRCA1, BRCA2 or a related gene has been lost. It is detected by a BRCA1/2 mutation or by genomic-scar scores such as the myChoice CDx GIS at a threshold of 42 or FoundationOne LOH, and it predicts benefit from PARP inhibitors and platinum. HRD is common in high-grade serous ovarian cancer and present in a substantial minority of Triple-negative breast cancer (TNBC). The term sits with the HRD & BRCA testing technology and the BRCA1 / BRCA2 (HRD) and PARP targets, and it is used by the PRIMA and PAOLA-1 trials, Rucaparib, the pairing of PARP inhibitor plus bevacizumab maintenance, Sabine Linn and the bottleneck on biomarker validation.

## Fields

- Kind: Term
- Last checked: 2026-09-04

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Homologous_recombination
- Wikipedia: https://en.wikipedia.org/wiki/Homologous_recombination

## Connected records

- terms: [BRCA reversion mutations](https://onco.cc/terms/brca-reversion-mutations/), [Enabling characteristic: genome instability and mutation](https://onco.cc/terms/genome-instability-mutation/), [Gene amplification and copy-number change](https://onco.cc/terms/gene-amplification/), [Genome-wide loss of heterozygosity (gLOH)](https://onco.cc/terms/genome-wide-loss-of-heterozygosity/), [Germline BRCA mutation (gBRCA)](https://onco.cc/terms/gbrca-mutation/), [High-grade serous ovarian carcinoma (HGSOC)](https://onco.cc/terms/hgsoc/), [Homologous recombination deficiency (HRD) in breast cancer](https://onco.cc/terms/hrd-in-breast-cancer/), [Platinum-sensitive / platinum-resistant](https://onco.cc/terms/platinum-sensitivity/), [What follows what in castration-resistant prostate cancer](https://onco.cc/terms/prostate-crpc-sequencing/), [Who is eligible for a PARP inhibitor in prostate cancer, and why the gene matters](https://onco.cc/terms/prostate-hrr-eligibility/)
- cancers: [BRCA or PALB2-mutant pancreatic ductal adenocarcinoma](https://onco.cc/cancers/brca-palb2-pdac/), [Gallbladder cancer](https://onco.cc/cancers/gallbladder/), [High-grade serous ovarian cancer](https://onco.cc/cancers/high-grade-serous-ovarian-cancer/), [Metastatic castration-resistant prostate cancer](https://onco.cc/cancers/prostate-mcrpc/), [Pancreatic acinar cell carcinoma](https://onco.cc/cancers/pancreatic-acinar-cell-carcinoma/), [Pancreatic ductal adenocarcinoma](https://onco.cc/cancers/pancreatic/), [Platinum-sensitive ovarian cancer](https://onco.cc/cancers/platinum-sensitive-ovarian-cancer/), [Prostate cancer](https://onco.cc/cancers/prostate/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- technologies: [HRD & BRCA testing](https://onco.cc/technologies/hrd-testing/), [HRD genomic scar scores (GIS, LOH, HRDetect)](https://onco.cc/technologies/hrd-genomic-scar-scores/), [RAD51 foci assay (functional HRD test)](https://onco.cc/technologies/rad51-foci-assay/), [Whole-exome & whole-genome sequencing](https://onco.cc/technologies/wes-wgs/)
- targets: [BRCA1 / BRCA2 (HRD)](https://onco.cc/targets/brca/), [PARP](https://onco.cc/targets/parp/)
- key papers: [Analysis of circulating cell-free DNA identifies multiclonal heterogeneity of BRCA2 reversion mutations associated with resistance to PARP inhibitors](https://onco.cc/key-papers/paper-quigley-brca2-reversion-cfdna-parp-resistance-cancer-discov-2017/), [Biomarkers for Systemic Therapy in Metastatic Breast Cancer: ASCO Guideline Update](https://onco.cc/key-papers/paper-asco-biomarkers-metastatic-breast-cancer-guideline-jco-2022/), [Carboplatin in BRCA1/2-mutated and triple-negative breast cancer BRCAness subgroups: the TNT Trial](https://onco.cc/key-papers/paper-tutt-nat-med/), [Genomic characterization of biliary tract cancers identifies driver genes and predisposing mutations](https://onco.cc/key-papers/paper-wardell-biliary-drivers-germline-j-hepatol-2018/), [Genomic methods identify homologous recombination deficiency in pancreas adenocarcinoma and optimize treatment selection](https://onco.cc/key-papers/paper-park-hrd-pancreatic-platinum-ccr-2020/), [Germline BRCA mutations are associated with higher risk of nodal involvement, distant metastasis and poor survival outcomes in prostate cancer](https://onco.cc/key-papers/paper-castro-germline-brca-prostate-outcomes-jco-2013/), [Germline BRCA2 mutations drive prostate cancers with distinct evolutionary trajectories](https://onco.cc/key-papers/paper-taylor-germline-brca2-evolutionary-trajectories-nat-commun-2017/), [Homologous recombination deficiency (HRD) score predicts response to platinum-containing neoadjuvant chemotherapy in patients with triple-negative breast cancer](https://onco.cc/key-papers/paper-telli-hrd-score-platinum-tnbc-ccr-2016/), [HRDetect is a predictor of BRCA1 and BRCA2 deficiency based on mutational signatures](https://onco.cc/key-papers/paper-davies-nat-med/), [Inherited DNA-repair gene mutations in men with metastatic prostate cancer](https://onco.cc/key-papers/paper-pritchard-inherited-dna-repair-metastatic-prostate-nejm-2016/), [Intraductal and ductal histology and lymphovascular invasion are associated with germline DNA-repair gene mutations in prostate cancer](https://onco.cc/key-papers/paper-isaacsson-velho-intraductal-germline-dna-repair-prostate-2018/), [Molecular profiling of biliary cancers reveals distinct molecular alterations and potential therapeutic targets](https://onco.cc/key-papers/paper-weinberg-biliary-profiling-jgo-2019/), [PAOLA-1: olaparib added to bevacizumab maintenance in newly diagnosed ovarian cancer, with benefit confined to HRD-positive tumours](https://onco.cc/key-papers/paper-paola-1-nejm-2019/), [PROfound: olaparib for metastatic castration-resistant prostate cancer with homologous recombination repair gene alterations](https://onco.cc/key-papers/paper-profound-nejm-2020/), [Prospective comprehensive genomic profiling of 3,476 primary and metastatic prostate tumours](https://onco.cc/key-papers/paper-chung-comprehensive-genomic-profiling-prostate-jco-po-2019/), [Real-time genomic characterization of advanced pancreatic cancer to enable precision medicine](https://onco.cc/key-papers/paper-aguirre-real-time-genomic-characterisation-pancreatic-cancer-discov-2018/), [SOLO-1: two years of olaparib maintenance after first-line chemotherapy for BRCA-mutated ovarian cancer](https://onco.cc/key-papers/paper-solo-1-nejm-2018/), [SU2C-PCF: integrative clinical genomics of advanced prostate cancer](https://onco.cc/key-papers/paper-robinson-integrative-clinical-genomics-advanced-prostate-cell-2015/), [Survival analysis of carboplatin added to an anthracycline/taxane-based neoadjuvant chemotherapy and HRD score as predictor of response-final results from GeparSixto](https://onco.cc/key-papers/paper-loibl-geparsixto-survival-hrd-ann-oncol-2018/), [TCGA: the molecular taxonomy of primary prostate cancer](https://onco.cc/key-papers/paper-tcga-molecular-taxonomy-primary-prostate-cell-2015/), [TOPARP-A: DNA-repair defects and olaparib in metastatic prostate cancer](https://onco.cc/key-papers/paper-mateo-toparp-a-olaparib-dna-repair-nejm-2015/), [TRITON2: rucaparib in men with metastatic castration-resistant prostate cancer harbouring a BRCA1 or BRCA2 alteration](https://onco.cc/key-papers/paper-abida-triton2-rucaparib-brca-jco-2020/), [TRITON3: rucaparib or physician's choice in metastatic castration-resistant prostate cancer](https://onco.cc/key-papers/paper-fizazi-triton3-rucaparib-nejm-2023/), [Whole genomes redefine the mutational landscape of pancreatic cancer](https://onco.cc/key-papers/paper-waddell-whole-genomes-pancreatic-nature-2015/), [Whole-genome sequencing of triple-negative breast cancers in a population-based clinical study](https://onco.cc/key-papers/paper-staaf-tnbc-whole-genome-scan-b-nat-med-2019/)
- trials: [PAOLA-1 / ENGOT-ov25](https://onco.cc/trials/paola-1/), [PRIMA / ENGOT-OV26](https://onco.cc/trials/prima/), [TNT (Triple Negative Trial)](https://onco.cc/trials/tnt/), [TRITON3](https://onco.cc/trials/triton3/)
- drugs: [myChoice CDx](https://onco.cc/drugs/mychoice-cdx/), [Rucaparib](https://onco.cc/drugs/rucaparib/)
- pairings: [PARP inhibitor + bevacizumab maintenance (HRD-positive)](https://onco.cc/pairings/parp-plus-bevacizumab/)
- roadmaps: [Triple-negative breast cancer roadmap: from a remainder defined by three negative tests to immunotherapy, antibody-drug conjugates and the residual disease problem](https://onco.cc/roadmaps/tnbc-roadmap/)
- biomarkers: [Germline BRCA1/2 pathogenic variant (gBRCAm)](https://onco.cc/biomarkers/brca-germline/), [Homologous recombination repair gene mutation in prostate cancer](https://onco.cc/biomarkers/hrr-gene-mutation/), [HRD-positive (genomic instability score)](https://onco.cc/biomarkers/hrd-positive/), [Tumour (somatic or germline) BRCA1/2 mutation and HRR gene alterations](https://onco.cc/biomarkers/brca-somatic/)
- people: [Sabine Linn](https://onco.cc/people/sabine-linn/)
- bottlenecks: [Biomarkers are not validated or standardised](https://onco.cc/bottlenecks/b-biomarker-validation/), [Inherited risk is mostly unidentified](https://onco.cc/bottlenecks/b-hereditary-risk/)
- ideas: [A functional test for homologous recombination deficiency validated across laboratories](https://onco.cc/ideas/idea-tr2-hrd-functional-standard/), [Test the drug in biomarker-negative patients too, so the biomarker can be validated](https://onco.cc/ideas/idea-tr2-marker-stratified-default/)
- collections: [Ovarian Cancer Research Alliance (OCRA)](https://onco.cc/collections/ovarian-cancer-research-alliance/)
- pathways: [Base excision repair, PARP & alkylation damage](https://onco.cc/pathways/base-excision-repair-parp/), [Double-strand break repair: HR versus end joining](https://onco.cc/pathways/homologous-recombination-repair/), [Mutagenesis & mutational signatures](https://onco.cc/pathways/mutagenesis-signatures/), [Synthetic lethality: paired dependencies](https://onco.cc/pathways/synthetic-lethality-map/)
- companies: [ARCAGY-GINECO](https://onco.cc/companies/arcagy-gineco/)

---
JSON: https://onco.cc/api/v1/entities/hrd.json