Germline variants in non-BRCA1/2 homologous recombination-related genes and ovarian cancer: Analysis of tumor phenotype and survival.

Authors

Ryan Kahn

Ryan M. Kahn

Memorial Sloan Kettering Cancer Center, New York, NY

Ryan M. Kahn , Pier Selenica , Thomas Boerner , Yonghong Xiao , Tiffany Sia , Margaret Sheehan , Qin Zhou , Alexia Iasonos , Rachel N. Grisham , Roisin Eilish O'Cearbhaill , Kara Long , Dennis S Chi , Zsofia Kinga Stadler , Kenneth Offit , Carol Aghajanian , Paul Sabbatini , Diana Mandelker , Dmitriy Zamarin , Britta Weigelt , Ying L Liu

Organizations

Memorial Sloan Kettering Cancer Center, New York, NY, Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, Memorial Sloan Kettering Cancer Center and Weill Cornell Medical College, New York, NY

Research Funding

U.S. National Institutes of Health
U.S. National Institutes of Health, MSKCC

Background: BRCA1/2-associated ovarian cancer (OC) exhibits homologous recombination (HR)-deficiency (HRD) and a better prognosis than BRCA1/2-wildtype (WT) OC. However, it is unclear if patients with germline pathogenic variants (gPV) in other HR-related genes have a similar tumor phenotype. We sought to define OC molecular features from patients with gPV in other HR genes and analyze survival compared to patients with BRCA1/2 and WT OC. Methods: We identified patients with OC treated at our institution who underwent tumor-normal sequencing using MSK-IMPACT targeting 341-505 cancer-related genes with germline analysis of ≥76 genes from 7/2015-12/2020. Biallelic inactivation was inferred via assessments of loss of heterozygosity (LOH) at gPV in non-BRCA1/2 HR-related genes (ATM, BARD1, BRIP1, FANCA, FANCC, NBN, PALB2, RAD50, RAD51B, RAD51C, and RAD51D). Clinical characteristics were compared to patients with BRCA1/2-associated and WT OC using non-parametric tests. Progression-free (PFS) and overall-survival (OS) were calculated from date of pathologic diagnosis using the Kaplan-Meier method. Left truncation at date of MSK-IMPACT consent was applied. Whole-exome sequencing (WES) was performed in a subset of OCs. Results: Of 882 patients with OC, 56 (6.3%) had gPV in non-BRCA1/2 HR-related genes compared to 95 (10.8%) patients with BRCA1-associated OC (58 germline, 37 somatic) and 59 (6.7%) patients with BRCA2-associated OC (40 germline, 19 somatic). Patients with a deleterious genetic alteration were diagnosed with OC at younger age and more likely to have high-grade serous histology compared to the WT group (p < 0.01). High rates of biallelic alterations were observed amongst gPV in BRIP1 (11/13), PALB2 (3/4), RAD51B (3/4), RAD51C (3/4), and RAD51D (8/10), and WES was performed in a subset (n = 27) of tumors from these patients with adequate tumor purity (>30%). We observed a higher tumor mutational burden (TMB), median 2.5 (1.1-6.0) vs. 1.2 (0.6-2.6) mut/Mb, and enrichment of HRD mutational signatures in tumors associated with PALB2 and RAD51B/C/D compared with BRIP1 (p < 0.01), although markers of telomeric-allelic imbalance (TAI), large-scale state transitions (LST) and fraction of genome altered (FGA) were similar. PFS and OS varied by gene group with best survival in BRCA1/2-associated OC, even after adjustment for clinical covariates in multivariable models (p < 0.01). Although we observed heterogeneity in PFS and OS for those with gPV in other HR-related genes by biallelic status and HRD phenotype, none had significantly better survival than those with WT OC. Conclusions: OCs associated with gPV in non-BRCA1/2 HR-related genes represent a heterogenous group. OCs in those with gPV in PALB2 and RAD51B/C/D preferentially harbored biallelic alterations and displayed an HRD phenotype.

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Abstract Details

Meeting

2023 ASCO Annual Meeting

Session Type

Poster Session

Session Title

Gynecologic Cancer

Track

Gynecologic Cancer

Sub Track

Ovarian Cancer

Citation

J Clin Oncol 41, 2023 (suppl 16; abstr 5565)

DOI

10.1200/JCO.2023.41.16_suppl.5565

Abstract #

5565

Poster Bd #

260

Abstract Disclosures

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