Prevalence of homologous recombination deficiency in ovarian, primary peritoneal, and/or fallopian tube cancer: results from HALO-Taiwan subset

Objective: Recognition of homologous recombination deficiency (HRD) has revolutionized ovarian cancer (OC) treatment paradigm.Our study aimed to determine the prevalence of HRD in Taiwanese patients with high-grade serous ovarian cancer (HGSOC), high-grade endometrioid ovarian cancer (HGEOC), primary peritoneal cancer (PPC), and/or fallopian tube cancer (FTC).Methods: The HALO-Taiwan, a cross-sectional, noninterventional study (NCT04991051) enrolled patients with stage III/IV HGSOC, HGEOC, PPC, or FTC having formalin-fixed paraffin-embedded tumor tissue blocks collected within the past 120 days of enrollment.The primary outcome was the prevalence of HRD.The secondary outcomes included prevalence of BRCA wild-type and loss of heterozygosity (LOH) positive status, tumor BRCA1/2 mutations, and other pathogenic mutations.The association of LOH status with demographic factors and pathogenic mutations was assessed using Cramer's V. Results: Of 68 patients (median age [range]: 60.0 [39.0-81.0]years) enrolled, the majority (92.6%) had primary OC followed by PPC (2.9%) and FTC (4.4%).The overall prevalence of HRD was 52.9%; 14.7% had tumor BRCA mutations, and 38.2% had BRCA wild-type LOHpositive status.LOH status showed a strong, significant positive correlation with age and ECOG status (V=0.50, p=0.027, for both).Conclusion: The HALO-Taiwan was the first observational study reporting HRD prevalence of 52.9% among patients with advanced OC in Taiwan.Our findings underscore the need to implement guideline-recommended testing for HRD as a part of the initial diagnostic work-up for all newly-diagnosed advanced high-grade OC patients to optimize treatment strategies.