# HRD-positive (genomic instability score)

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

## TL;DR

HRD-positive means the tumour's genome carries the scars of failed double-strand break repair (or a BRCA mutation), measured as a genomic instability score. In ovarian cancer it selects niraparib, and olaparib with bevacizumab, as first-line maintenance.

## Summary

The Myriad myChoice CDx combines tumour BRCA1/2 status with a genomic instability score built from loss of heterozygosity, telomeric allelic imbalance and large-scale state transitions; the assay calls HRD-positive at a GIS of 42 or more (the PRIMA and PAOLA-1 trials' cut-off) or any deleterious BRCA mutation. Niraparib's US label defines HRD-positive status as 'a deleterious or suspected deleterious BRCA mutation, and/or genomic instability' and the olaparib plus bevacizumab first-line maintenance indication is for HRD-positive advanced ovarian cancer. Because the scar accumulates over time, HRD status is read on tumour tissue and does not capture reversion, which is why HRD-positive tumours can still be PARP-resistant.

## Fields

- Kind: Biomarker
- Last checked: 2026-09-23
- Also known as: HRD; HRD-positive; HRD positive; homologous recombination deficiency; genomic instability score; GIS; GIS >= 42; myChoice HRD; HRD score; genomic scar
- Tags: biomarker; brca; genome-wide

## Sources

- ZEJULA prescribing information (DailyMed): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b7f675e2-159c-490c-b6f4-3f16d9492b7d
- Lynparza prescribing information (DailyMed): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=741ff3e3-dc1a-45a6-84e5-2481b27131aa

## Connected records

- biomarkers: [Folate receptor alpha expression (FRα-positive, PS2+ >= 75%)](https://onco.cc/biomarkers/folr1-expression/), [Germline BRCA1/2 pathogenic variant (gBRCAm)](https://onco.cc/biomarkers/brca-germline/), [Tumour (somatic or germline) BRCA1/2 mutation and HRR gene alterations](https://onco.cc/biomarkers/brca-somatic/)
- cancers: [High-grade serous ovarian cancer](https://onco.cc/cancers/high-grade-serous-ovarian-cancer/), [Ovarian cancer](https://onco.cc/cancers/ovarian/)
- drugs: [Bevacizumab](https://onco.cc/drugs/bevacizumab/), [myChoice CDx](https://onco.cc/drugs/mychoice-cdx/), [Niraparib](https://onco.cc/drugs/niraparib/), [Olaparib](https://onco.cc/drugs/olaparib/)
- terms: [Homologous recombination deficiency (HRD)](https://onco.cc/terms/hrd/), [Platinum-sensitive / platinum-resistant](https://onco.cc/terms/platinum-sensitivity/)
- targets: [BRCA1 / BRCA2 (HRD)](https://onco.cc/targets/brca/)

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