Loss of Heterozygosity- LOH

Loss of Heterozygosity (LOH) in the tumor is observed due to defective repair of double-stranded DNA breaks, when the homologous recombination pathway is defective (Homologous Recombination Deficiency, HRD). Clinical evidence suggests that ovarian cancer patients who have higher levels of genomic LOH have an increased likelihood of responding to treatment with PARP inhibitors.
Although high levels of %LOH are most commonly seen in breast and ovarian cancers, they can be found in a multitude of cancer types and affect their response to PARP inhibitor therapy. In addition, increased LOH has also been linked to sensitivity to platinum-containing chemotherapy regimens in patients with ovarian and breast cancer as well as other tumor types.