HRD follow-up call: Flashcards
HRD stands for:
Homologous Recombination Deficiency
What does it mean?
The cancer cells are lacking a very important mechanism for DNA repair. Multiple genes are related to this.
How can you test this?
Look at the HRR genes, see if there is a mutation and if so, we treat that accordingly.
How many methods do we have?
DNA and RNA
When do we use the DNA method?
Breast and Ovarian
When do we use RNA method?
For everything else. All other cancers. We specifically call out prostate and pancreatic.
If the clinician needs the HRD for breast or ovarian, do you need the normal match as well?
Yes. We need the normal match to see if the BRCA1/2 is present.
Tumor purity for DNA and RNA (HRD test)
DNA- 40%
RNA- 30%
There are two different ways that patients can test positive for HRD using the DNA method, what are they?
- DNA GWLOH
- Evidence of BRCA1/2 loss
loss of heterozygosity means?
loss of both copies of the gene (BRCA1 & BRCA2)
What are we looking for with RNA?
- 20,000 genes (mRNA expression) , RNA sequencing
Is RNA sequencing dependent on how much of the tumor sample is left?
Yes
What does it mean for a patient to have HRD?
They are lacking the method of DNA repair (HRD)
What is the primary therapeutic option if a patient has HRD?
PARP inhibitor therapy
Can we talk about this at Tempus?
Not really. We can’t get into PARP inhibition, but we can respond to the clinician into using their own clinical judgment there. We can’t link the HRD to PARP inhibition therapy AT ALL. No clinical advice on this.
