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Copy number variants in BRCA1 and BRCA2 genes in Polish patients with breast and ovarian cancer.

PURPOSE: BRCA1 and BRCA2 are key susceptibility genes in hereditary breast and ovarian cancer (HBOC), with mutational status guiding PARP inhibitor therapy. While single-nucleotide variants (SNVs) predominate, the prevalence of copy number variants (CNVs) varies significantly across different populations. This study aims to determine the incidence of BRCA1/2 CNVs in the Polish population, where data remain scarce due to non-mandatory CNV testing. METHODS: We retrospectively analysed the results of genetic tests assessing the presence of BRCA1/2 CNVs performed in 2720 individuals tested at the Lower Silesian Oncology Centre (2021-2024), including 2702 breast/ovarian cancer patients and 18 unaffected relatives. The mean age was 54.7 ± 15.15 years. Genetic testing involved DNA extraction, NGS, and MLPA for CNV confirmation. Variants were classified according to ACMG-AMP guidelines and verified through independent testing. RESULTS: In this study, no BRCA2 CNVs were identified, consistent with previous Central European findings. Pathogenic BRCA1 CNVs were detected in 0.85% of the analyzed cohort and in 0.52% of the cancer patient subgroup, affecting 23 individuals from 13 families. Eight distinct BRCA1 CNVs were detected, the most common being exon 21 deletion. Affected families exhibited a high incidence of HBOC-related cancers, with early-onset breast cancer and a notable proportion of triple-negative breast cancer cases. CONCLUSIONS: This study highlights the clinical significance of BRCA1 CNVs in Polish patients with HBOC-spectrum cancers and their families. Although rare, these variants were associated with aggressive cancer phenotypes and early onset. Given their diagnostic and therapeutic implications, BRCA1 CNVs should be routinely analysed in high-risk families to ensure accurate detection and personalised treatment planning.

Humans

Risk-reducing bilateral salpingo-oophorectomy in women with BRCA1 or BRCA2 mutations.

BACKGROUND: The presence of deleterious mutations in breast cancer 1 gene (BRCA1) or breast cancer 2 gene (BRCA2) significantly increases the risk of developing some cancers, such as breast and high-grade serous cancer (HGSC) of ovarian, tubal and peritoneal origin. Risk-reducing salpingo-oophorectomy (RRSO) is usually recommended to BRCA1 or BRCA2 carriers after completion of childbearing. Despite prior systematic reviews and meta-analyses on the role of RRSO in reducing the mortality and incidence of breast, HGSC and other cancers, RRSO is still an area of debate and it is unclear whether RRSO differs in effectiveness by type of mutation carried. OBJECTIVES: To assess the benefits and harms of RRSO in women with BRCA1 or BRCA2 mutations. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 7) in The Cochrane Library, MEDLINE Ovid, Embase Ovid and trial registries, with no language restrictions up to July 2017. We handsearched abstracts of scientific meetings and other relevant publications. SELECTION CRITERIA: We included non-randomised trials (NRS), prospective and retrospective cohort studies, and case series that used statistical adjustment for baseline case mix using multivariable analyses comparing RRSO versus no RRSO in women without a previous or coexisting breast, ovarian or fallopian tube malignancy, in women with or without hysterectomy, and in women with a risk-reducing mastectomy (RRM) before, with or after RRSO. DATA COLLECTION AND ANALYSIS: We extracted data and performed meta-analyses of hazard ratios (HR) for time-to-event variables and risk ratios (RR) for dichotomous outcomes, with 95% confidence intervals (CI). To assess bias in the studies, we used the ROBINS-I 'Risk of bias' assessment tool. We quantified inconsistency between studies by estimating the I2 statistic. We used random-effects models to calculate pooled effect estimates. MAIN RESULTS: We included 10 cohort studies, comprising 8087 participants (2936 (36%) surgical participants and 5151 (64%) control participants who were BRCA1 or BRCA2 mutation carriers. All the studies compared RRSO with or without RRM versus no RRSO (surveillance). The certainty of evidence by GRADE assessment was very low due to serious risk of bias. Nine studies, including 7927 women, were included in the meta-analyses. The median follow-up period ranged from 0.5 to 27.4 years. MAIN OUTCOMES: overall survival was longer with RRSO compared with no RRSO (HR 0.32, 95% CI 0.19 to 0.54; P < 0.001; 3 studies, 2548 women; very low-certainty evidence). HGSC cancer mortality (HR 0.06, 95% CI 0.02 to 0.17; I&#xb2; = 69%; P < 0.0001; 3 studies, 2534 women; very low-certainty evidence) and breast cancer mortality (HR 0.58, 95% CI 0.39 to 0.88; I&#xb2; = 65%; P = 0.009; 7 studies, 7198 women; very low-certainty evidence) were lower with RRSO compared with no RRSO. None of the studies reported bone fracture incidence. There was a difference in favour of RRSO compared with no RRSO in terms of ovarian cancer risk perception quality of life (MD 15.40, 95% CI 8.76 to 22.04; P < 0.00001; 1 study; very low-certainty evidence). None of the studies reported adverse events.Subgroup analyses for main outcomes: meta-analysis showed an increase in overall survival among women who had RRSO versus women without RRSO who were BRCA1 mutation carriers (HR 0.30, 95% CI 0.17 to 0.52; P < 0001; I&#xb2; = 23%; 3 studies; very low-certainty evidence) and BRCA2 mutation carriers (HR 0.44, 95% CI 0.23 to 0.85; P = 0.01; I&#xb2; = 0%; 2 studies; very low-certainty evidence). The meta-analysis showed a decrease in HGSC cancer mortality among women with RRSO versus no RRSO who were BRCA1 mutation carriers (HR 0.10, 95% CI 0.02 to 0.41; I&#xb2; = 54%; P = 0.001; 2 studies; very low-certainty evidence), but uncertain for BRCA2 mutation carriers due to low frequency of HGSC cancer deaths in BRCA2 mutation carriers. There was a decrease in breast cancer mortality among women with RRSO versus no RRSO who were BRCA1 mutation carriers (HR 0.45, 95% CI 0.30 to 0.67; I&#xb2; = 0%; P < 0.0001; 4 studies; very low-certainty evidence), but not for BRCA2 mutation carriers (HR 0.88, 95% CI 0.42 to 1.87; I&#xb2; = 63%; P = 0.75; 3 studies; very low-certainty evidence). One study showed a difference in favour of RRSO versus no RRSO in improving quality of life for ovarian cancer risk perception in women who were BRCA1 mutation carriers (MD 10.70, 95% CI 2.45 to 18.95; P = 0.01; 98 women; very low-certainty evidence) and BRCA2 mutation carriers (MD 13.00, 95% CI 3.59 to 22.41; P = 0.007; very low-certainty evidence). Data from one study showed a difference in favour of RRSO and RRM versus no RRSO in increasing overall survival (HR 0.14, 95% CI 0.02 to 0.98; P = 0.0001; I&#xb2; = 0%; low-certainty evidence), but no difference for breast cancer mortality (HR 0.78, 95% CI 0.51 to 1.19; P = 0.25; very low-certainty evidence). The risk estimates for breast cancer mortality according to age at RRSO (50 years of age or less versus more than 50 years) was not protective and did not differ for BRCA1 (HR 0.85, 95% CI 0.64 to 1.11; I&#xb2; = 16%; P = 0.23; very low-certainty evidence) and BRCA2 carriers (HR 0.88, 95% CI 0.42 to 1.87; I&#xb2; = 63%; P = 0.75; very low-certainty evidence). AUTHORS' CONCLUSIONS: There is very low-certainty evidence that RRSO may increase overall survival and lower HGSC and breast cancer mortality for BRCA1 and BRCA2 carriers. Very low-certainty evidence suggests that RRSO reduces the risk of death from HGSC and breast cancer in women with BRCA1 mutations. Evidence for the effect of RRSO on HGSC and breast cancer in BRCA2 carriers was very uncertain due to low numbers. These results should be interpreted with caution due to questionable study designs, risk of bias profiles, and very low-certainty evidence. We cannot draw any conclusions regarding bone fracture incidence, quality of life, or severe adverse events for RRSO, or for effects of RRSO based on type and age at risk-reducing surgery. Further research on these outcomes is warranted to explore differential effects for BRCA1 or BRCA2 mutations.

Adult

Comprehensive Genomic Profiling Reveals the Mutational Spectrum and Clinical Significance of BRCA1/2 and Other Cancer-Susceptibility Genes in Breast Cancer Patients from Southern Tunisia.

BACKGROUND/OBJECTIVES: This study aims to investigate the mutational spectrum of BRCA1 and BRCA2 genes in a cohort of breast cancer (BC) patients from southern Tunisia, and to evaluate their clinical and prognostic significance. Additionally, this study explores the contribution of other cancer predisposition genes and the prevalence of variants of uncertain significance (VUS). RESULTS: Among the 165 patients included, pathogenic or likely pathogenic variants (P/LPVs) in BRCA1/BRCA2 were identified in 19 cases (11.51%), including 8 in BRCA1 and 11 in BRCA2. The presence of BRCA P/LPVs associated with young patients (p = 0.006) and those with TNBC (p = 0.036). Beyond BRCA1/2, PV/LPVs were detected in other cancer-related genes, including TP53 (n = 3), CHEK2, RAD50 (n = 2 cases each), and MUTYH, BARD1, and BRIP1 (one case each). Furthermore, 56 VUS were identified; among them, 7 were prioritized based on in silico predictive analyses, suggesting a potential deleterious effect. However, these VUS should not be used for clinical decision-making without additional evidence from functional and familial segregation studies. CONCLUSIONS: Our findings provide novel insights into the genetic landscape of breast cancer in southern Tunisia, highlighting the clinical relevance of BRCA1/2 mutations and the contribution of other susceptibility genes. These results support the personalized management of breast cancer patients and the implementation of expanded multigene panel testing in routine clinical practice to improve genetic counseling.

BRCA1

Towards a CRISPeR understanding of homologous recombination with high-throughput functional genomics.

CRISPR-dependent genome editing enables the study of genes and mutations on a large scale. Here we review CRISPR-based functional genomics technologies that generate gene knockouts and single nucleotide variants (SNVs) and discuss how their use has provided new important insights into the function of homologous recombination (HR) genes. In particular, we highlight discoveries from CRISPR screens that have contributed to define the response to PARP inhibition in cells deficient for the HR genes BRCA1 and BRCA2, uncover genes whose loss causes synthetic lethality in combination with BRCA1/2 deficiency, and characterize the function of BRCA1/2 SNVs of uncertain clinical significance. Further use of these approaches, combined with next-generation CRISPR-based technologies, will aid to dissect the genetic network of the HR pathway, define the impact of HR mutations on cancer etiology and treatment, and develop novel targeted therapies for HR-deficient tumors.

Gene Regulatory Networks

Lurbinectedin, a selective inhibitor of oncogenic transcription, in patients with pretreated germline BRCA1/2 metastatic breast cancer: results from a phase II basket study.

BACKGROUND: Lurbinectedin, a selective inhibitor of oncogenic transcription, has shown preclinical antitumor activity against homologous recombination repair-deficient models and preliminary clinical activity in BRCA1/2 breast cancer. PATIENTS AND METHODS: This phase II basket multitumor trial (NCT02454972) evaluated lurbinectedin 3.2 mg/m2 1-h intravenous infusion every 3 weeks in a cohort of 21 patients with pretreated germline BRCA1/2 breast cancer. Patients with any hormone receptor and human epidermal growth factor receptor 2 status were enrolled. The primary efficacy endpoint was overall response rate (ORR) according to RECIST v1.1. Secondary endpoints included duration of response (DoR), progression-free survival (PFS), overall survival (OS) and safety. RESULTS: Confirmed partial response (PR) was observed in six patients [ORR&#xa0;= 28.6%; 95% confidence interval (CI) 11.3% to 52.2%] who had received a median of two prior advanced chemotherapy lines. Lurbinectedin was active in both BRCA mutations: four PRs in 11 patients (36.4%) with BRCA2 and two PRs in 10 patients (20.0%) with BRCA1. Median DoR was 8.6 months, median PFS was 4.1 months and median OS was 16.1 months. Stable disease (SD) was observed in 10 patients (47.6%), including 3 with unconfirmed response in a subsequent tumor assessment [ORR unconfirmed&#xa0;= 42.9% (95% CI 21.8% to 66.0%)]. Clinical benefit rate (PR&#xa0;+ SD &#x2265; 4 months) was 76.2% (95% CI 52.8% to 91.8%). No objective response was observed among patients who had received prior poly (ADP-ribose) polymerase inhibitors. The most common treatment-related adverse events (AEs) were nausea (61.9%), fatigue (38.1%) and vomiting (23.8%). These AEs were mostly grade 1/2. The most common grade 3/4 toxicity was neutropenia (42.9%: grade 4, 23.8%: with no febrile neutropenia). CONCLUSIONS: This phase II study met its primary endpoint and showed activity of lurbinectedin in germline BRCA1/2 breast cancer. Lurbinectedin showed a predictable and manageable safety profile. Considering the exploratory aim of this trial as well as previous results in other phase II studies, further development of lurbinectedin in this indication is warranted.

Humans

Brazilian Society of Surgical Oncology Analysis in Cost-Effectiveness of Population-Based BRCA Testing for Ovarian Cancer in the Public Health System.

Although ovarian cancer is the most lethal among gynecological cancers, access to massive BRCA testing is still limited. Its cost-effectiveness is still a topic of discussion in several countries. In Brazil, olaparib was recently incorporated into the public health system, access to BRCA testing is still limited. In this article, we aim to review the cost-effectiveness of offering BRCA testing to the at-risk population. A working group composed of 14 specialists in surgical oncology and cancer genetics was established to discuss the cost-effectiveness of population-based BRCA testing for ovarian cancer. The project was divided into five main areas, each with subtopics assigned among the 14 participants. They were: the existing clinical testing guidelines, the current healthcare infrastructure in the Brazilian public health system, cost-effectiveness analysis, challenges in implementing prophylactic surgeries, and family counseling and risk communication. A comprehensive literature review was conducted, followed by a series of meetings among the article's contributors to reach consensus on unresolved issues. These discussions aimed to build recommendations based on the best available scientific evidence. Using as a basis the current structure already existing within the Brazilian public health service (SUS [Sistema &#xda;nico de Saude]), and based on the testing of the at-risk population chosen by our experts, we estimated savings. The net savings for a population of 100&#x2009;000 women would range from BRL 7030.30 (US$1255.41) to BRL 1853.92 (US$331.05). And these costs could have an even greater impact when public service PARP inhibitors are incorporated. The working group of the Brazilian Society of Surgical Oncology understands that large-scale BRCA testing is cost-effective, especially when risk-reducing surgery is implemented. Other measures are important, such as training teams of non-specialists to recognize the population at risk, in addition to creating an entire line of care for patients with ovarian cancer in the SUS.

Humans

International trends in concurrent hysterectomy at risk-reducing surgery in BRCA1/2 pathogenic variant carriers: a mixed-methods study.

BACKGROUND: BRCA1/2 pathogenic variant carriers are advised to undergo a risk-reducing salpingo-oophorectomy between the ages of 35 and 45 due to their increased risk of tubo-ovarian cancer. A concurrent hysterectomy may be performed at the time of risk-reducing salpingo-oophorectomy. Currently, the international execution of hysterectomy during risk-reducing surgery and the factors guiding related decision-making are unknown. OBJECTIVE: We aimed to evaluate the international execution of concurrent hysterectomy during risk-reducing surgery for tubo-ovarian cancer and factors guiding providers' decision-making about this. STUDY DESIGN: We conducted a mixed-methods study. First, we executed a quantitative analysis with data from the Women choosIng Surgical Prevention (WISP) and TUBectomy with delayed oophorectomy as Alternative for risk-reducing salpingo-oophorectomy in high-risk Women to assess the Safety of Prevention (TUBA-WISP II) study, both prospective preferential trials assessing surgical strategies for tubo-ovarian cancer prevention. Data were collected via electronic case report forms. Concurrent hysterectomy during risk-reducing salpingo-oophorectomy was compared between Europe, North- and South America, and Australia using Kruskal-Wallis tests. We used univariable logistic regression models to estimate the association of personal and prevention-related characteristics with the execution of hysterectomy at risk-reducing salpingo-oophorectomy in women from North- and South America. Subsequently, we conducted focus group interviews with gynecologic providers from 12 countries who provide preventive care for individuals at increased risk of tubo-ovarian cancer to identify indications, barriers, and facilitators for the execution of hysterectomy with risk-reducing salpingo-oophorectomy. RESULTS: In the quantitative analysis, we included 2181 participants, of whom 1647 (75.5%) were from Europe, 498 (22.8%) from North- and South America, and 36 (1.7%) from Australia. Execution of hysterectomy at risk-reducing salpingo-oophorectomy differed substantially between continents, with an execution of 48.8% in North- and South America, 14.2% in Australia, and 2.8% in Europe (P<.001). Execution of concurrent hysterectomy at risk-reducing salpingectomy in women from North- and South America occurred more often in women with a BRCA1 pathogenic variant compared to a BRCA2 pathogenic variant (adjusted odds ratio 0.4 [95% confidence interval, 0.2-0.7]). In the qualitative analysis, we interviewed 23 healthcare providers and identified 31 barriers and 32 facilitators regarding hysterectomy execution during risk-reducing salpingo-oophorectomy. A total of 8 different indications were mentioned, but opinions varied on the validity and weight given to each indication. Providers indicated that important barriers or facilitators for concurrent hysterectomy included a lack of clear guidelines, cultural variation between countries, (lack of) consensus within departments, and different interpretation of the endometrial cancer risk. CONCLUSION: Internationally, there is a large variation in execution of hysterectomy during risk-reducing surgery with frequent utilization in North- and South America, and rare utilization in Europe. This could be explained by the interpretation of indications for hysterectomy by providers, which might be explained by cultural variation, the absence of clear guidelines, and limited scientific evidence.

Humans

Predictors of BRCA1/2 genetic testing among Black women with breast cancer: a population-based study.

Evidence shows that Black women diagnosed with breast cancer are substantially less likely to undergo BRCA testing and other multipanel genetic testing compared to White women, despite having a higher incidence of early-age onset breast cancer and triple-negative breast cancer (TNBC). Our study identifies predictors of BRCA testing among Black women treated for breast cancer and examines differences between BRCA testers and nontesters. We conducted an analysis of 945 Black women ages 18-64 diagnosed with localized or regional-stage invasive breast cancer in Pennsylvania and Florida between 2007 and 2009. Logistic regression was used to identify predictors of BRCA 1/2 testing. Few (27%) (n&#xa0;=&#xa0;252) of the participants reported having BRCA testing. In the multivariate analysis, we found that perceived benefits of BRCA testing (predisposing factor) ([OR], 1.16; 95% CI: 1.11-1.21; P&#xa0;<&#xa0;0.001), income (enabling factor) ([OR], 2.10; 95% CI: 1.16-3.80; p&#xa0;=&#xa0;0.014), and BRCA mutation risk category (need factor) ([OR], 3.78; 95% CI: 2.31-6.19; P&#xa0;<&#xa0;0.001) predicted BRCA testing. These results suggest that interventions to reduce disparities in BRCA testing should focus on identifying patients with high risk of mutation, increasing patient understanding of the benefits of BRCA testing, and removing financial and other administrative barriers to genetic testing.

Adolescent

Psychologically informed reminder messages for promoting BRCA1/2 carrier screening: evidence from a large-scale population-based study.

Psychologically Informed Reminder Messages (PIRMs) may promote health-behavior change, but their impact on preventive genetic screening is unclear. Due to low adherence to a screening program, Clalit Health Services initiated an intervention to encourage BRCA1/2 carrier screening in July 2022. This observational study assesses the effectiveness of the intervention in encouraging screening and its spillover effect on related healthcare utilization, focusing on Ashkenazi Jewish females aged 25-50 with no relevant cancer history. Patients were randomly assigned to receive one of five PIRMs. Four PIRMs utilized different psychological strategies, while the fifth served as a control. The effectiveness of the intervention on screening adherence was assessed using a regression discontinuity analysis. A Cox regression assessed the effectiveness of the four PIRMs compared to the control. Spillover effects on healthcare utilization were evaluated using logistic regressions. The intervention showed a positive correlation with increased adherence to screening (&#x3b2; = 0.37, 95% CI: 0.01-0.72). The "Barrier Remover" PIRM emphasized ease (hazards ratio&#x2009;=&#x2009;1.09, 95% CI: 1.02-1.16), while the "Health Control" PIRM focused on autonomy (hazards ratio&#x2009;=&#x2009;1.07, 95% CI: 1.01-1.14), both indicating greater effectiveness than the control. The findings suggest a positive short-term spillover effect of the "Health Control" PIRM on healthcare utilization compared to the control (odds ratio&#x2009;=&#x2009;1.16, 95% CI: 1.04-1.29). PIRMs effectively increased BRCA1/2 carrier screening adherence, demonstrating a scalable, low-cost intervention to improve preventive healthcare uptake. The effect varied by the psychological strategies, highlighting the potential of tailored behavioral interventions to enhance public health.

Humans

DNA binding and RAD51 engagement by the BRCA2 C-terminus orchestrate DNA repair and replication fork preservation.

The tumor suppressor BRCA2 participates in DNA double-strand break repair by RAD51-dependent homologous recombination and protects stressed DNA replication forks from nucleolytic attack. We demonstrate that the C-terminal Recombinase Binding (CTRB) region of BRCA2, encoded by gene exon 27, harbors a DNA binding activity. CTRB alone stimulates the DNA strand exchange activity of RAD51 and permits the utilization of RPA-coated ssDNA by RAD51 for strand exchange. Moreover, CTRB functionally synergizes with the Oligonucleotide Binding fold containing DNA binding domain and BRC4 repeat of BRCA2 in RPA-RAD51 exchange on ssDNA. Importantly, we show that the DNA binding and RAD51 interaction attributes of the CTRB are crucial for homologous recombination and protection of replication forks against MRE11-mediated attrition. Our findings shed light on the role of the CTRB region in genome repair, reveal remarkable functional plasticity of BRCA2, and help explain why deletion of Brca2 exon 27 impacts upon embryonic lethality.

DNA Replication

Prevalence of homologous recombination repair genes alterations in metastatic castration-resistant prostate cancer, a multicentric study.

INTRODUCTION: Homologous Recombination Repair (HRR) genes alterations are a resistance mechanism to therapies by taxanes or Androgen Receptor Signalling inhibitors in Metastatic Castration Resistant Prostate Cancer (mCRPC). BRCA-mutated mCRPC patients are eligible to poly adenosine diphosphateribose polymerase inhibitors (PARPi). Therefore, assessing the population-specific prevalence of HRR-related genes alterations is of public healthcare importance. METHODS: This retrospective, non-interventional, multicentric study was conducted across 6 reference French centers in a "real-life" setting. 788 paraffin-embedded mCRPC patient-samples were included and submitted to testing for BRCA1/2 in six different centers; additionally, non-BRCA HRR-related genes were investigated in two different centers. RESULTS: Among the samples, n=602 (76.4%) were contributive for molecular testing. In multivariate analysis by logistic regression and sensitivity analysis, only sample age (P<0.01), sample surface area (P=0.02) and institution (P=0.018) remained statistically significant. BRCA alterations were detected in n=39/602 (6.5%) of contributive samples, with n=35 and n=4 alterations of BRCA2 and BRCA1 respectively. Non-BRCA HRR-related genes alterations were detected in n=12/157 (7.6%) of contributive samples, with alterations of mainly ATM (n=6, 3.8%), CDK12 (n=4, 2.5%) and CHEK2 (n=2, 1.3%). DISCUSSION: In this study, testing contributivity was similar or higher that of other studies in the literature, and observed mutations prevalences were similar to that of other screenings of western populations. Harmonising per-centres protocols and enhancing molecular testing contributivity with the screening of circulating DNA samples and expanding its range by including non-BRCA HRR-related genes in all reference centres will enable more patients to be accurately treated by targeted therapies. LEVEL OF EVIDENCE: 3 (grade C).

Male

Surviving without BRCA2: MLH1 gets R-looped in to curtail genomic instability.

While breast cancer 2 (BRCA2) loss of heterozygosity (LOH) promotes cancer initiation, it can also induce death in nontransformed cells. In contrast, mismatch repair gene mutL homolog 1 (MLH1) is a tumor-suppressor gene that protects cells from cancer development through repairing mismatched base pairs during DNA mismatch repair (MMR). Sengodan et al., in this issue of the JCI, reveal an interplay between the 2 genes: MLH1 promoted the survival of BRCA2-deficient cells independently of its MMR function. MLH1 protected replication forks from degradation, while also resolving R-loops, thereby reducing genomic instability. Moreover, MLH1 expression was regulated directly by estrogen, shedding light into the hormone-responsive nature of many BRCA2 mutant breast cancers. These results provide important insight into the genetics that drive the initiation of BRCA2-mutated breast cancers.

Humans

Established Cancer Predisposition Genes in Single and Multiple Cancer Diagnoses.

IMPORTANCE: Much of the understanding of cancer risk associated with rare pathogenic variants (RPVs) is derived from family-based studies or clinically ascertained samples, which may be limited by ascertainment and selection bias. OBJECTIVE: To quantify associations between RPVs in previously implicated cancer predisposition genes and single and multiple cancer diagnoses in a large population-based study. DESIGN, SETTING, AND PARTICIPANTS: In this genetic association study, whole-exome sequencing data were used from the UK Biobank, a UK population-based cohort that enrolled participants aged 40 to 69 years between 2006 and 2010. Participants who were involved in the whole-exome sequencing release of 200&#x202f;000 genomes in 2020 were included in this study. This analysis included White participants only, as findings in other racial and ethnic groups had small sample sizes. Participants were diagnosed before or after biobank enrollment until March 2024. EXPOSURES: The sequencing data of a set of 96 previously implicated cancer predisposition genes were analyzed and compared using 2 methods. To determine the statistical significance of an association, a robust optimal sequence kernel association test was used, while odds ratios (ORs) and 95% CIs were obtained through Firth logistic regression. MAIN OUTCOMES AND MEASURES: The primary study outcome was the diagnosis of 1 of 11 cancers (bladder, breast, central nervous system, colorectal, lung, melanoma, ovary, pancreatic, prostate, renal, thyroid) defined by relevant diagnosis codes in inpatient hospital diagnosis, cancer registry, and/or death registry data. RESULTS: Data from 183&#x202f;627 participants (101&#x202f;414 [55.2%] female) were analyzed, including 25&#x202f;824 participants with at least 1 cancer diagnosis, of whom 23&#x202f;704 (91.8%) had a single cancer diagnosis and 2130 (8.2%) had 2 or more cancer diagnoses. A total of 157&#x202f;793 controls had no cancer diagnosis. The median (IQR) age was 62 (56-65) years in participants with at least 1 cancer diagnosis, compared to 57 (50-63) years in those without a cancer diagnosis. Genetic variation in 16 genes was significantly associated with at least 1 cancer of interest (ATM, BARD1, BRCA1, BRCA2, BRIP1, CDKN2A, CHEK2, HOXB13, MITF, MLH1, MSH2, MSH6, NF1, PALB2, RAD51C, and RAD51D). The presence of an RPV in 1 of these 16 genes was associated with increased odds of at least 1 cancer (OR, 1.87; 95% CI, 1.76-1.98) and multiple primary cancers (OR, 2.56; 95% CI, 2.18-2.99). Carrier frequency was 6.28% and 8.36%, respectively. CONCLUSIONS AND RELEVANCE: This genetic association study demonstrates several established associations between cancer predisposition genes and cancer diagnoses in an unselected population-based study. These results also demonstrate that RPVs in cancer predisposition genes are associated with multiple primary cancer diagnoses, suggesting that multigene panel testing may be warranted in these individuals.

Humans

Reanalysis of BRCA1/2 negative high risk ovarian cancer patients reveals novel germline risk loci and insights into missing heritability.

While up to 25% of ovarian cancer (OVCA) cases are thought to be due to inherited factors, the majority of genetic risk remains unexplained. To address this gap, we sought to identify previously undescribed OVCA risk variants through the whole exome sequencing (WES) and candidate gene analysis of 48 women with ovarian cancer and selected for high risk of genetic inheritance, yet negative for any known pathogenic variants in either BRCA1 or BRCA2. In silico SNP analysis was employed to identify suspect variants followed by validation using Sanger DNA sequencing. We identified five pathogenic variants in our sample, four of which are in two genes featured on current multi-gene panels; (RAD51D, ATM). In addition, we found a pathogenic FANCM variant (R1931*) which has been recently implicated in familial breast cancer risk. Numerous rare and predicted to be damaging variants of unknown significance were detected in genes on current commercial testing panels, most prominently in ATM (n = 6) and PALB2 (n = 5). The BRCA2 variant p.K3326*, resulting in a 93 amino acid truncation, was overrepresented in our sample (odds ratio = 4.95, p = 0.01) and coexisted in the germline of these women with other deleterious variants, suggesting a possible role as a modifier of genetic penetrance. Furthermore, we detected loss of function variants in non-panel genes involved in OVCA relevant pathways; DNA repair and cell cycle control, including CHEK1, TP53I3, REC8, HMMR, RAD52, RAD1, POLK, POLQ, and MCM4. In summary, our study implicates novel risk loci as well as highlights the clinical utility for retesting BRCA1/2 negative OVCA patients by genomic sequencing and analysis of genes in relevant pathways.

Adult

Clinicopathologic Spectrum and Intraprostatic Heterogeneity of Primary Mismatch Repair-Deficient Prostate Cancer.

Mismatch repair deficiency (MMRd) is identified in a small subset of prostate cancers and has implications for therapy selection and germline testing. The clinicopathologic spectrum of primary MMRd prostate cancer remains incompletely characterized. We evaluated 32 primary treatment-naive MMRd prostatic adenocarcinomas identified at a single institution. Grade group distribution included GG5 (n=12, 38%), GG4 (n=4, 13%), GG3 (n=7, 22%), and GG2 (n=9, 28%). Intraductal and/or invasive cribriform carcinoma was identified in 78% of cases overall and in 78% of GG2 tumors. MMR protein loss predominantly involved MSH2/MSH6 (78%), with isolated MSH6 loss in 16% and MLH1/PMS2 loss in 6%. Concordant pathogenic MMR gene alterations were identified on targeted NGS in all cases, while concurrent Tier 1/2 HRR gene alterations were present in 11 cases (35%), including ATM, BRCA1, and BRCA2. Germline testing performed in 15 cases identified Lynch syndrome in 5 (33%). MMR immunohistochemistry performed on multiple tissue blocks in 14 cases revealed discordant MMR status between tumor foci in 8 cases (57%), with MMR deficiency consistently restricted to the highest-grade focus and retained expression in spatially separate lower-grade foci. One additional case demonstrated apparent intratumoral heterogeneity within a single biopsy core, with MMR deficiency restricted to a higher-grade component and retained expression in the adjacent lower-grade tumor. These findings demonstrate a broader clinicopathologic spectrum of primary MMRd prostate cancer than previously recognized. Frequent discordance of MMR status between tumor foci highlights the importance of evaluating the highest-grade tumor focus when assessing multifocal primary prostate cancer.

cribriform

Distinct roles of BRCA2 in replication fork protection in response to hydroxyurea and DNA interstrand cross-links.

DNA interstrand cross-links (ICLs) are a form of DNA damage that requires the interplay of a number of repair proteins including those of the Fanconi anemia (FA) and the homologous recombination (HR) pathways. Pathogenic variants in the essential gene BRCA2/FANCD1, when monoallelic, predispose to breast and ovarian cancer, and when biallelic, result in a severe subtype of Fanconi anemia. BRCA2 function in the FA pathway is attributed to its role as a mediator of the RAD51 recombinase in HR repair of programmed DNA double-strand breaks (DSB). BRCA2 and RAD51 functions are also required to protect stalled replication forks from nucleolytic degradation during response to hydroxyurea (HU). While RAD51 has been shown to be necessary in the early steps of ICL repair to prevent aberrant nuclease resection, the role of BRCA2 in this process has not been described. Here, based on the analysis of BRCA2 DNA-binding domain (DBD) mutants (c.8488-1G>A and c.8524C>T) discovered in FA patients presenting with atypical FA-like phenotypes, we establish that BRCA2 is necessary for the protection of DNA at ICLs. Cells carrying BRCA2 DBD mutations are sensitive to ICL-inducing agents but resistant to HU treatment consistent with relatively high HR repair in these cells. BRCA2 function at an ICL protects against DNA2-WRN nuclease-helicase complex and not the MRE11 nuclease that is implicated in the resection of HU-induced stalled replication forks. Our results also indicate that unlike the processing at HU-induced stalled forks, the function of the SNF2 translocases (SMARCAL1, ZRANB3, or HLTF), implicated in fork reversal, are not an integral component of the ICL repair, pointing to a different mechanism of fork protection at different DNA lesions.

BRCA2 Protein

Reinforcement learning-based dynamic ensemble for missense variant effect prediction and tiered prioritization of VUS.

BACKGROUND: Accurate classification of missense variants remains a challenging task despite major advances in genomics. Numerous computational models have been developed to assist in variant classification, but often require repeated integration and benchmarking efforts. Ensemble methods have been proposed to overcome the limitations of single predictors, but mostly rely on fixed, predefined weights that constrain their ability to capture interactions among predictive signals. METHODS: We present GenixRL, a dynamic ensemble framework that reformulates model fusion as a reinforcement learning optimization problem. GenixRL uses a Q-learning agent to learn a policy that dynamically weights the probabilistic outputs of complementary predictors, including BayesDel (addAF and noAF), ClinPred, and MetaRNN. Replacing static weighting with policy learning allows GenixRL to adaptively identify optimal weightings and substantially improve classification accuracy. RESULTS: In benchmark evaluation against 25 state-of-the-art predictors, GenixRL achieved an AUROC of 0.9644 on an independent ClinVar dataset. On saturation genome editing assays for BRCA1 and BRCA2, GenixRL achieved the best performance and ranked highest on 14 of 17 clinically significant genes in a zero-shot evaluation. Applied to uncertain and conflicting ClinVar variants, GenixRL enabled tiered, evidence-based prioritization of hundreds of thousands of variants as likely pathogenic or pathogenic with high confidence, supported by orthogonal population evidence from gnomAD. CONCLUSION: GenixRL advances pathogenicity prediction for missense variants and provides an adaptive ensemble that sorts variants of uncertain significance into tiered candidates for expert curation and functional validation.

Mutation, Missense

Clinically actionable genomic alterations in breast cancer brain metastases.

BACKGROUND: Breast cancer brain metastases (BCBMs) represent a critical unmet clinical need in metastatic breast cancer (MBC) and the identification of novel therapeutic targets is urgently needed in this context. In this study, we describe clinically actionable targets in BCBMs using comprehensive genomic profiling. PATIENTS AND METHODS: Genomic DNA was extracted from formalin-fixed paraffin-embedded archival BCBM samples and analyzed using the commercially available Agilent SureSelect V6 whole exome sequencing (WES) kit and an Illumina NovaSeq 6000 platform. Pathogenic alterations were classified as actionable alterations (AAs) if they met the updated MBC or tumor-agnostic ESMO Scale for Clinical Actionability of Molecular Targets (ESCAT) I or II criteria of the ESCAT scale. RESULTS: WES data from 56 BCBM samples were available [33.9% hormone receptor (HR)-negative/human epidermal growth factor receptor (HER)2-negative; 25.0% HR-positive/HER2-negative; and 38% HER2-positive]. ESCAT I/II AAs were detected in 76.8% (n = 43) of all BCBMs and the most frequently detected AAs were in genes involved in the homologous recombination repair pathway (BRCA1/BRCA2/PALB2; 53.6% overall). Biallelic inactivation of BRCA1, BRCA2, or PALB2 was observed in 19.6% of samples, with higher rates in HER2-negative BCBMs (26% in HR-negative /HER2-negative and 21% in HR-positive/HER2-negative). ESCAT I/II PIK3CA/AKT1/PTEN pathway alterations were present in 48.2% of samples and, in particular, in 50% of HR-positive/HER2-negative BCBMs. No ESR1 mutation was detected in HR-positive/HER2-negative BCBMs. The prognostic impact of previously described AAs was evaluated overall and according to breast cancer subtype. Twenty-three BCBMs (41%) were classified as HER2-positive; among these, 3 (13%) presented a hotspot PIK3CA mutation and 7 (30%) presented a PTEN deletion. Among patients with HER2-positive BCBMs, the identification of a hotspot PIK3CA mutation was significantly associated with worse prognosis. CONCLUSIONS: ESCAT I/II actionable genomic alterations are frequent in BCBMs, highlighting the potential for genomically targeted treatments in this setting.

ESCAT