Jerry Lanchbury, PhD, chief scientific officer, Myriad Genetics, Inc., describes the HRD (homologous recombination deficiency) test.
One fundamental defect of a number of tumors is that they lack the ability to repair double-strand breaks in DNA. This defect, Lanchbury says, is why the BRCA1/2 gene causes hereditary breast and ovarian cancer.
There are 3 versions of the HRD test: whole genome tumor loss of heterozygosity profiles (HRD-LOH), telomeric allelic imbalance (HRD-TAI), and large-scale state transitions (HRD-LST). These 3 tests are closely correlated but are not the same, and see a fundamental property of the tumor. When combined, these tests are extremely useful in detecting sensitivity to platinum. In the future, these tests might also be used to determine which patients will be sensitive to PARP inhibitors that are currently in development.