Frequency of homologous recombination repair alterations in ovarian cancer in Chinese population.

Abstract

e17531 Background: Ovarian Cancer (OC) is the most lethal cancer of all gynecological malignancies.Circulating tumor DNA (ctDNA) has received substantial attention in recent years resulting from the non-invasive, safe and effective method with considerable potential for clinical diagnosis and treatment management in patients with OC. Here, we assessed the mutational feature in homologous recombination repair (HRR) using ctDNA in OC. Methods: Plasma ctDNA was isolated from blood of patients and then was analyzed by AcornMed Biotechnology NGS-based assay for 808 genes panel for genomic alterations. The somatic and germline pathogenic mutations were identified in 12 HRR genes (ATM, BRCA1, BRCA2, BRIP1, CHEK1, CHEK2, FANCA, PALB2, RAD51B, RAD51C, RAD51D, RAD54L). Results: At our institution, 85 patients underwent NGS analysis of ovarian cancer specimens. The median age was 57 (range from 26 to 83). Twenty-six patients(42.34%) harbored a mutation in at least 1 of the HRR genes in their tumor. The most commonly altered HRR gene was BRCA1 (18.25%), followed by BRCA2 (8.76%), ATM (5.84%), RAD51D(3.65%), CHEK2 (2.92%), FANCA(2.19%) and RAD51C (0.73%). To determine the difference of mutation landscape in HRR between Chinese and western populations, we compared prevalence and spectrum in cases between our cohort and the cohort of Heeke et al 1(Table). Prevalence of HRR were different from the Western cases(42.34% vs 20%, P＜0.05). Of note, BRCA1, BRCA2, ATM and CHEK2 alterations rate was higher in our cohort, and BRIP1 and PALB2 were only detected in the western cohort. Conclusions: CtDNA can characterize the mutational feature of HRR in OC. Around 42.3% of patients with OC harbour germline or somatic HRR mutations. The expanded use of PARP inhibitors in HRR deficient tumours using a signature of HRR by ctDNA in clinical practice requires validation.[Table: see text]