Excessive transcription-replication conflicts are a vulnerability of BRCA1-mutant cancers.

BRCA1 mutations are associated with increased breast and ovarian cancer risk. BRCA1-mutant tumors are high-grade, recurrent, and often become resistant to standard therapies. Herein, we performed a targeted CRISPR-Cas9 screen and identified MEPCE, a methylphosphate capping enzyme, as a synthetic lethal interactor of BRCA1. Mechanistically, we demonstrate that depletion of MEPCE in a BRCA1-deficient setting led to dysregulated RNA polymerase II (RNAPII) promoter-proximal pausing, R-loop accumulation, and replication stress, contributing to transcription-replication collisions. These collisions compromise genomic integrity resulting in loss of viability of BRCA1-deficient cells. We also extend these findings to another RNAPII-regulating factor, PAF1. This study identifies a new class of synthetic lethal partners of BRCA1 that exploit the RNAPII pausing regulation and highlight the untapped potential of transcription-replication collision-inducing factors as unique potential therapeutic targets for treating cancers associated with BRCA1 mutations.

Impact of veliparib, paclitaxel dosing regimen, and germline BRCA status on the primary treatment of serous ovarian cancer - an ancillary data analysis of the VELIA trial.

OBJECTIVE: In the Phase 3 VELIA trial (NCT02470585), veliparib added to carboplatin plus paclitaxel concomitantly and as maintenance for women with newly-diagnosed advanced ovarian cancer significantly improved progression-free survival (PFS) versus chemotherapy alone. Here we present exploratory analyses by paclitaxel dosing schedule and germline BRCA (gBRCA) status. METHODS: Women with untreated ovarian carcinoma were randomized (1:1:1) to: veliparib during chemotherapy and maintenance (veliparib-throughout), veliparib during chemotherapy followed by placebo maintenance (veliparib-combination only), or placebo during chemotherapy and maintenance (control). Chemotherapy included carboplatin plus dose-dense (DD; weekly) or every-3-week (Q3W) paclitaxel (a stratification factor at randomization), selected at the investigator's discretion pre-randomization. PFS was assessed by paclitaxel dosing schedule using a Cox proportional hazard model adjusted by treatment arm and stratification factors; safety was analyzed based on paclitaxel dosing schedule and gBRCA status. RESULTS: 1132 patients were analyzed by paclitaxel schedule. Pooled treatment arms demonstrated longer median PFS with DD (n = 586) versus Q3W (n = 546) paclitaxel (ITT: 20.5 vs 15.7 months, hazard ratio [HR] 0.77; homologous recombination proficient cancer: 15.1 vs 11.8 months, HR 0.64; BRCAwt: 18.0 vs 12.9 months, HR 0.70). Comparison between arms favored veliparib-throughout versus control in both DD (PFS, 24.2 vs 18.3 months, hazard ratio 0.67) and Q3W (19.3 vs 14.6, hazard ratio 0.69) subgroups. DD paclitaxel was associated with higher incidence of Grade 3/4 neutropenia, fatigue, and anemia versus Q3W. There were no differences in toxicity between gBRCAm (n = 211) and gBRCAwt (n = 902) subgroups. CONCLUSIONS: DD paclitaxel was tolerable and associated with longer PFS in the HR proficient and gBRCAwt groups, versus Q3W. gBRCA status did not impact safety.

Impact of homologous recombination status and responses with veliparib combined with first-line chemotherapy in ovarian cancer in the Phase 3 VELIA/GOG-3005 study.

OBJECTIVE: In the Phase 3 VELIA trial (NCT02470585), PARP inhibitor (PARPi) veliparib was combined with first-line chemotherapy and continued as maintenance for patients with ovarian carcinoma enrolled regardless of chemotherapy response or biomarker status. Here, we report exploratory analyses of the impact of homologous recombination deficient (HRD) or proficient (HRP) status on progression-free survival (PFS) and objective response rates during chemotherapy. METHODS: Women with Stage III-IV ovarian carcinoma were randomized to veliparib-throughout, veliparib-combination-only, or placebo. Stratification factors included timing of surgery and germline BRCA mutation status. HRD status was dichotomized at genomic instability score 33. During combination therapy, CA-125 levels were measured at baseline and each cycle; radiographic responses were assessed every 9 weeks. RESULTS: Of 1140 patients randomized, 742 had BRCA wild type (BRCAwt) tumors (HRP, n = 373; HRD/BRCAwt, n = 329). PFS hazard ratios between veliparib-throughout versus control were similar in both BRCAwt populations (HRD/BRCAwt: 22.9 vs 19.8 months; hazard ratio 0.76; 95% confidence interval [CI] 0.53-1.09; HRP: 15.0 vs 11.5 months; hazard ratio 0.765; 95% CI 0.56-1.04). By Cycle 3, the proportion with ≥90% CA-125 reduction from baseline was higher in those receiving veliparib (pooled arms) versus control (34% vs 23%; P = 0.0004); particularly in BRCAwt and HRP subgroups. Complete response rates among patients with measurable disease after surgery were 24% with veliparib (pooled arms) and 18% with control. CONCLUSIONS: These results potentially broaden opportunities for PARPi utilization among patients who would not qualify for frontline PARPi maintenance based on other trials.

First- and second-degree family history of ovarian and breast cancer in relation to risk of invasive ovarian cancer in African American and white women.

Family history (FH) of ovarian cancer and breast cancer are well-established risk factors for ovarian cancer, but few studies have examined this association in African American (AA) and white women by histotype. We assessed first- and second-degree FH of ovarian and breast cancer and risk of epithelial ovarian cancer in the Ovarian Cancer in Women of African Ancestry Consortium. Analyses included 1052 AA cases, 2328 AA controls, 2380 white cases and 3982 white controls. Race-specific odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multilevel logistic regression with adjustment for covariates. Analyses were stratified by histotype (high-grade serous vs others). First-degree FH of ovarian cancer was associated with high-grade serous carcinoma in AA (OR = 2.32, 95% CI: 1.50, 3.59) and white women (OR = 2.48, 95% CI: 1.82, 3.38). First-degree FH of breast cancer increased risk irrespective of histotype in AAs, but with high-grade serous carcinoma only in white women. Associations with second-degree FH of ovarian cancer were observed for overall ovarian cancer in white women and with high-grade serous carcinoma in both groups. First-degree FH of ovarian cancer and of breast cancer, and second-degree FH of ovarian cancer is strongly associated with high-grade serous ovarian carcinoma in AA and white women. The association of FH of breast cancer with high-grade serous ovarian carcinoma is similar in white women and AA women, but may differ for other histotypes.

Retesting of women who are negative for a BRCA1 and BRCA2 mutation using a 20-gene panel.

BACKGROUND: The value of retesting women who previously tested negative for a pathogenic variant (mutation) in BRCA1 and BRCA2 using an expanded panel of breast and ovarian cancer genes is unclear. METHODS: We studied 110 BRCA1/2-negative women who were retested using a panel of 20 breast and/or ovarian cancer susceptibility genes at the Advanced Molecular Diagnostics Laboratory (AMDL) at Mount Sinai Hospital in Toronto between March 2017 and March 2019. All patients had previously tested negative for BRCA pathogenic variants at the AMDL between January 2012 and March 2018 and were subsequently referred for retesting by their physician. RESULTS: Overall, six pathogenic variants in genes other than BRCA1 and BRCA2 were found (prevalence 5.5%). There were two pathogenic variants found in RAD51C, and one found in each of BRIP1, PALB2, PMS2 and PTEN. The prevalence of pathogenic variants was 6.5% for women affected with cancer (6 of 93), including 4.9% for women with breast cancer (4 of 82) and 22.2% for women with ovarian cancer (2 of 9). None of the 17 unaffected women had a clinically significant or pathogenic variant. There were 44 women (40%) for whom the result of the panel test was inconclusive due to the detection of a variant of uncertain significance. CONCLUSIONS: Our findings indicate that the retesting of BRCA1/2-negative individuals with an expanded panel of 20 breast and ovarian cancer genes can produce clinically relevant results, with a yield of 5.5% for pathogenic variants in genes other than BRCA1 and BRCA2.

Clinical utility of hereditary cancer panel testing: Impact of PALB2, ATM, CHEK2, NBN, BRIP1, RAD51C, and RAD51D results on patient management and adherence to provider recommendations.

BACKGROUND: Although management guidelines exist for several genes associated with a 2-fold to 5-fold increase in the relative risk for certain cancers, the value of testing for them remains controversial. METHODS: De-identified personal and family history data for 654 individuals with pathogenic variants (PVs) in PALB2, ATM, CHEK2, NBN, BRIP1, RAD51C, and/or RAD51D were analyzed for pretest and post-test candidacy for guideline-recommended management of cancer risk. These individuals were invited to complete a survey about provider recommendations and their adherence. RESULTS: Twenty-four percent of CHEK2, ATM, PALB2, or NBN PV carriers were appropriate for consideration of annual breast magnetic resonance imaging screening before genetic testing, with the remaining 76% appropriate only after testing. No BRIP1, RAD51C, or RAD51D PV carriers were appropriate for consideration of risk-reducing salpingo-oophorectomy before genetic testing; 100% were appropriate only after testing. Seventeen percent of CHEK2 PV carriers were appropriate for earlier and more frequent colonoscopy before genetic testing, with the remaining 83% appropriate only after testing. Provider recommendations for annual breast magnetic resonance imaging, consideration of risk-reducing salpingo-oophorectomy, and earlier and more frequent colonoscopy were reported by 42%, 26%, and 66% of breast, ovarian, and colorectal cancer risk PV carriers, respectively, before genetic testing, versus 82%, 79%, and 81%, respectively, after testing. Nearly all respondents had planned or undertaken provider-recommended management. CONCLUSIONS: Testing for PALB2, ATM, CHEK2, NBN, BRIP1, RAD51C, and RAD51D changed management for those carrying PVs. Provider recommendations were aligned with guidelines, and patients adhered to recommendations, both of which are critical for reducing both long-term cancer morbidity and mortality.

An immune-centric exploration of BRCA1 and BRCA2 germline mutation related breast and ovarian cancers.

BACKGROUND: BRCA1/2 germline mutation related cancers are candidates for new immune therapeutic interventions. This study was a hypothesis generating exploration of genomic data collected at diagnosis for 19 patients. The prominent tumor mutation burden (TMB) in hereditary breast and ovarian cancers in this cohort was not correlated with high global immune activity in their microenvironments. More information is needed about the relationship between genomic instability, phenotypes and immune microenvironments of these hereditary tumors in order to find appropriate markers of immune activity and the most effective anticancer immune strategies. METHODS: Mining and statistical analyses of the original DNA and RNA sequencing data and The Cancer Genome Atlas data were performed. To interpret the data, we have used published literature and web available resources such as Gene Ontology, The Cancer immunome Atlas and the Cancer Research Institute iAtlas. RESULTS: We found that BRCA1/2 germline related breast and ovarian cancers do not represent a unique phenotypic identity, but they express a range of phenotypes similar to sporadic cancers. All breast and ovarian BRCA1/2 related tumors are characterized by high homologous recombination deficiency (HRD) and low aneuploidy. Interestingly, all sporadic high grade serous ovarian cancers (HGSOC) and most of the subtypes of triple negative breast cancers (TNBC) also express a high degree of HRD. CONCLUSIONS: TMB is not associated with the magnitude of the immune response in hereditary BRCA1/2 related breast and ovarian cancers or in sporadic TNBC and sporadic HGSOC. Hereditary tumors express phenotypes as heterogenous as sporadic tumors with various degree of "BRCAness" and various characteristics of the immune microenvironments. The subtyping criteria developed for sporadic tumors can be applied for the classification of hereditary tumors and possibly also characterization of their immune microenvironment. A high HRD score may be a good candidate biomarker for response to platinum, and potentially PARP-inhibition. TRIAL REGISTRATION: Phase I Study of the Oral PI3kinase Inhibitor BKM120 or BYL719 and the Oral PARP Inhibitor Olaparib in Patients With Recurrent TNBC or HGSOC (NCT01623349), first posted on June 20, 2012. The design and the outcome of the clinical trial is not in the scope of this study.

Mis-splicing in breast cancer: identification of pathogenic BRCA2 variants by systematic minigene assays.

Splicing disruption is a common mechanism of gene inactivation associated with germline variants of susceptibility genes. To study the role of BRCA2 mis-splicing in hereditary breast/ovarian cancer (HBOC), we performed a comprehensive analysis of variants from BRCA2 exons 2-9, as well as the initial characterization of the regulatory mechanisms of such exons. A pSAD-based minigene with exons 2-9 was constructed and validated in MCF-7 cells, producing the expected transcript (1016-nt/V1-BRCA2_exons_2-9-V2). DNA variants from mutational databases were analyzed by NNSplice and Human Splicing Finder softwares. To refine ESE-variant prediction, we mapped the regulatory regions through a functional strategy whereby 26 exonic microdeletions were introduced into the minigene and tested in MCF-7 cells. Thus, we identified nine spliceogenic ESE-rich intervals where ESE-variants may be located. Combining bioinformatics and microdeletion assays, 83 variants were selected and genetically engineered in the minigene. Fifty-three changes impaired splicing: 28 variants disrupted the canonical sites, four created new ones, 10 abrogated enhancers, eight created silencers and three caused a double-effect. Notably, nine spliceogenic-ESE variants were located within ESE-containing intervals. Capillary electrophoresis and sequencing revealed more than 23 aberrant transcripts, where exon skipping was the most common event. Interestingly, variant c.67G>A triggered the usage of a noncanonical GC-donor 4-nt upstream. Thirty-six variants that induced severe anomalies (>60% aberrant transcripts) were analyzed according to the ACMG guidelines. Thus, 28 variants were classified as pathogenic, five as likely pathogenic and three as variants of uncertain significance. Interestingly, 13 VUS were reclassified as pathogenic or likely pathogenic variants. In conclusion, a large fraction of BRCA2 variants (∼64%) provoked splicing anomalies lending further support to the high prevalence of this disease-mechanism. The low accuracy of ESE-prediction algorithms may be circumvented by functional ESE-mapping that represents an optimal strategy to identify spliceogenic ESE-variants. Finally, systematic functional assays by minigenes depict a valuable tool for the initial characterization of splicing anomalies and the clinical interpretation of variants. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Prognosis of BRCA1/2-negative breast cancer patients with HBOC risk factors compared with sporadic breast cancer patients without HBOC risk factors.

OBJECTIVE: Demands for genetic counseling with BRCA1/2 examination have markedly increased. Accordingly, the incidence of uninformative results on BRCA1/2 mutation status has also increased. Because most patients examined for BRCA1/2 mutation have a high risk of hereditary breast and/or ovarian cancer, many patients suffer psychological distress even when the BRCA1/2 result is negative. We compared oncological outcomes between BRCA1/2-negative breast cancer with high risk of hereditary breast and/or ovarian cancer and sporadic breast cancer without risk of hereditary breast and/or ovarian cancer. METHODS: The criteria for high risk for hereditary breast and/or ovarian cancer were defined as family history of breast and/or ovarian cancer in first- or second-degree relative, early onset breast cancer at <35 years old and bilateral breast cancer. Patients were matched maximally 1:3 into those who identified as negative for BRCA1/2 mutation with risk of hereditary breast and/or ovarian cancer (study group) and those who were not examined for BRCA1/2 mutation without risk for hereditary breast and/or ovarian cancer (control group). Matched variables were pathologic stage, estrogen receptor, progesterone receptor and human epidermal growth factor receptor-2 status. RESULTS: All matching variables were successfully matched. Median follow-up duration was 57.8 months. There was no significant difference between the groups in disease-free survival (log-rank P = 0.197); however, the study group showed significantly better overall survival and breast cancer-specific survival (both P < 0.0001). We conducted subgroup analysis in the middle-aged group (36-54) and showed no significant difference for disease-free survival (P = 0.072) but significantly better overall survival and breast cancer-specific survival in the study group (P = 0.002 and P < 0.0001). CONCLUSIONS: BRCA1/2-negative breast cancer patients who had hereditary breast and/or ovarian cancer risk factors showed similar disease-free survival and better overall survival and breast cancer-specific survival compared with those with sporadic breast cancer without hereditary breast and/or ovarian cancer risk factors.

Risk factors for lymph node metastasis of ovarian, fallopian tube and primary peritoneal cancer in hereditary breast and ovarian cancer syndrome.

BACKGROUND: To establish an individualized surgical strategy for lymphadenectomy in ovarian cancer patients with the germline BRCA1 and BRCA2 pathogenic variants (BRCA1+ and BRCA2+), we investigated the clinicopathological characteristics that are involved in the increased risk of lymph node metastasis. METHODS: We retrospectively reviewed the data of Japanese women registered in the database of the Japanese Hereditary Breast and Ovarian Cancer Consortium, who underwent BRCA1 and BRCA2 genetic testing. RESULTS: We evaluated the predictors of lymph node metastasis in all patients with the information of age at the diagnosis, disease site, histological subtype, 2014 FIGO stage, personal breast cancer history and family history; 233, 153 and 32 patients in the BRCA- (no pathogenic variant), BRCA1+ and BRCA2+ groups, respectively. The prevalence of lymph node metastasis was not markedly different between BRCA- (20.0%), BRCA1+ (18.4%) and BRCA2+ (26.2%). Multivariate analysis revealed an absence of a family history of ovarian cancer as an independent predictor for an increased risk of lymph node metastasis in BRCA1+, and the prevalence of lymph node metastasis was 11.7 and 42.0% in the groups with and without a family history of ovarian cancer, respectively. This subgroup without a family history of ovarian cancer did not show any correlation with a particular variant of BRCA1, including two common variants of c.188 T > A and c.2800C > T. CONCLUSIONS: This study suggested that certain genetic factors related to the penetrance of hereditary breast and ovarian cancer syndrome altered the frequency of lymph node metastasis in BRCA1+ ovarian cancer, and family history may be useful to personalize the indication of lymphadenectomy.

Molecular Features and Clinical Management of Hereditary Gynecological Cancers.

Hereditary gynecological cancers are caused by several inherited genes. Tumors that arise in the female reproductive system, such as ovaries and the uterus, overlap with hereditary cancers. Several hereditary cancer-related genes are important because they might lead to therapeutic targets. Treatment of hereditary cancers should be updated in line with the advent of various new methods of evaluation. Next-generation sequencing has led to rapid, economical genetic analyses that have prompted a concomitant and significant paradigm shift with respect to hereditary cancers. Molecular tumor profiling is an epochal method for determining therapeutic targets. Clinical treatment strategies are now being designed based on biomarkers based on tumor profiling. Furthermore, the National Comprehensive Cancer Network (NCCN) guidelines significantly changed the genetic testing process in 2020 to initially consider multi-gene panel (MGP) evaluation. Here, we reviewed the molecular features and clinical management of hereditary gynecological malignancies, such as hereditary breast and ovarian cancer (HBOC), and Lynch, Li-Fraumeni, Cowden, and Peutz-Jeghers syndromes. We also reviewed cancer-susceptible genes revealed by MGP tests.

High-risk breast cancer surveillance with MRI: 10-year experience from the German consortium for hereditary breast and ovarian cancer.

PURPOSE: To report on 10 years of high-risk service screening with annual MRI in the German Consortium for Hereditary Breast and Ovarian Cancer (GC-HBOC). METHODS: A cohort of 4,573 high-risk, previously unaffected women (954 BRCA1 carriers, 598 BRCA2 carriers, 3021 BRCA1/2 non-carriers) participating in the GC-HBOC surveillance program was prospectively followed. Screening outcomes for 14,142 screening rounds with MRI between 2006 and 2015 were analyzed and stratified by risk group, type of screening round, and age. RESULTS: A total of 221 primary breast cancers (185 invasive, 36 in situ) were diagnosed within 12 months of an annual screening round with MRI. Of all cancers, 84.5% (174/206, 15 unknown) were stage 0 or I. In BRCA1 carriers, 16.9% (10/59, 5 unknown) of all incident cancers (screen-detected and interval cancers combined) and in BRCA2 carriers 12.5% (3/24, 4 unknown) were stage IIA or higher, compared to only 4.8% (2/42, 2 unknown) in high-risk BRCA1/2 non-carriers. Program sensitivity was 89.6% (95% CI 84.9-93.0) with no significant differences in sensitivity between risk groups or by age. Specificity was significantly lower in the first screening round (84.6%, 95% CI 83.6-85.7) than in subsequent screening rounds (91.1%, 95% CI 90.6-91.7), p < 0.001. Cancer detection rates (CDRs) and as a result positive predictive values were strongly dependent on type of screening round, risk group and patient age. CDRs ranged from 43.5‰ (95% CI 29.8-62.9) for the first screening round in BRCA2 carriers to 2.9‰ (95% CI 1.3-6.3) for subsequent screening rounds in high-risk non-carriers in the age group 30 to 39 years. CONCLUSIONS: High-risk screening with MRI was successfully implemented in the GC-HBOC with high sensitivity and specificity. Risk prediction and inclusion criteria in high-risk non-carriers need to be adjusted to improve CDRs and thus screening efficacy in these patients.

Population-based genetic testing of asymptomatic women for breast and ovarian cancer susceptibility.

PURPOSE: The identification of carriers of hereditary breast and ovarian cancer (HBOC) gene variants through family cancer history alone is suboptimal, and most population-based genetic testing studies have been limited to founder mutations in high-risk populations. Here, we determine the clinical utility of identifying actionable variants in a healthy cohort of women. METHODS: Germline DNA from a subset of healthy Australian women participating in the lifepool project was screened using an 11-gene custom sequencing panel. Women with clinically actionable results were invited to attend a familial cancer clinic (FCC) for post-test genetic counseling and confirmatory testing. Outcomes measured included the prevalence of pathogenic variants, and the uptake rate of genetic counseling, risk reduction surgery, and cascade testing. RESULTS: Thirty-eight of 5908 women (0.64%) carried a clinically actionable pathogenic variant. Forty-two percent of pathogenic variant carriers did not have a first-degree relative with breast or ovarian cancer and 89% pursued referral to an FCC. Forty-six percent (6/13) of eligible women pursued risk reduction surgery, and the uptake rate of cascade testing averaged 3.3 family members per index case. CONCLUSION: Within our cohort, HBOC genetic testing was well accepted, and the majority of high-risk gene carriers identified would not meet eligibility criteria for genetic testing based on their existing family history.

Characterization of spliceogenic variants located in regions linked to high levels of alternative splicing: BRCA2 c.7976+5G > T as a case study.

Many BRCA1 and BRCA2 (BRCA1/2) genetic variants have been studied at mRNA level and linked to hereditary breast and ovarian cancer due to splicing alteration. In silico tools are reliable when assessing variants located in consensus splice sites, but we may identify variants in complex genomic contexts for which bioinformatics is not precise enough. In this study, we characterize BRCA2 c.7976 + 5G > T variant located in intron 17 which has an atypical donor site (GC). This variant was identified in three unrelated Spanish families and we have detected exon 17 skipping as the predominant transcript occurring in carriers. We have also detected several isoforms (Δ16-18, Δ17,18, Δ18, and ▼17q224 ) at different expression levels among carriers and controls. This study remarks the challenge of interpreting genetic variants when multiple alternative isoforms are present, and that caution must be taken when using in silico tools to identify potential spliceogenic variants located in GC-AG introns.

Landscape of pathogenic variations in a panel of 34 genes and cancer risk estimation from 5131 HBOC families.

PURPOSE: Integration of gene panels in the diagnosis of hereditary breast and ovarian cancer (HBOC) requires a careful evaluation of the risk associated with pathogenic or likely pathogenic variants (PVs) detected in each gene. Here we analyzed 34 genes in 5131 suspected HBOC index cases by next-generation sequencing. METHODS: Using the Exome Aggregation Consortium data sets plus 571 individuals from the French Exome Project, we simulated the probability that an individual from the Exome Aggregation Consortium carries a PV and compared it to the estimated frequency within the HBOC population. RESULTS: Odds ratio conferred by PVs within BRCA1, BRCA2, PALB2, RAD51C, RAD51D, ATM, BRIP1, CHEK2, and MSH6 were estimated at 13.22 [10.01-17.22], 8.61 [6.78-10.82], 8.22 [4.91-13.05], 4.54 [2.55-7.48], 5.23 [1.46-13.17], 3.20 [2.14-4.53], 2.49 [1.42-3.97], 1.67 [1.18-2.27], and 2.50 [1.12-4.67], respectively. PVs within RAD51C, RAD51D, and BRIP1 were associated with ovarian cancer family history (OR = 11.36 [5.78-19.59], 12.44 [2.94-33.30] and 3.82 [1.66-7.11]). PALB2 PVs were associated with bilateral breast cancer (OR = 16.17 [5.48-34.10]) and BARD1 PVs with triple-negative breast cancer (OR = 11.27 [3.37-25.01]). Burden tests performed in both patients and the French Exome Project population confirmed the association of PVs of BRCA1, BRCA2, PALB2, and RAD51C with HBOC. CONCLUSION: Our results validate the integration of PALB2, RAD51C, and RAD51D in the diagnosis of HBOC and suggest that the other genes are involved in an oligogenic determinism.

Hereditary Breast and Ovarian Cancer Syndrome: Moving Beyond BRCA1 and BRCA2.

The recent implementation of next generation sequencing and multigene platforms has expanded the spectrum of hereditary breast and ovarian cancer syndrome, beyond the traditional genes BRCA1 and BRCA2. A large number of other moderate penetrance genes have now been uncovered, which also play critical roles in repairing double stranded DNA breaks through the homologous recombination pathway. This review discusses the landmark discoveries of BRCA1 and BRCA2, the homologous repair pathway and new genes discovered in hereditary breast and ovarian cancer syndrome, as well as their clinicopathologic significance and implications for genetic testing. It also highlights the new role of PARP inhibitors in the context of synthetic lethality and prophylactic surgical options.

Clinical and Pathological Characteristics of Incidental Diagnostic Early Occult Malignancy After Risk-Reducing Salpingo-Oophorectomy in BRCA Mutation Carriers.

OBJECTIVE: Carriers of familial BRCA mutations are at high risk of early development of ovarian tubal or peritoneal cancers. The definite preventative treatment for these cases is early, risk-reducing, bilateral salpingo-oophorectomy (BSO). The aims of the study were to describe the incidence and source of early occult malignancy after risk-reducing salpingo-oophorectomy in carriers of Ashkenazi Jewish BRCA mutations and to characterize the clinical and pathological features of this unique population. METHODS: Data were collected retrospectively regarding women who underwent BSO in our gynecologic oncology unit from January 2002 through July 2012, after a positive test for a BRCA1 or BRCA2 mutation. RESULTS: The following 92 cases of BRCA mutations were included: 53 BRCA1, 37 BRCA2, and 2 with both mutations. After risk-reducing salpingo-oophorectomy, 5 (5.4%) of the patients were found to have early occult adnexal malignancy upon pathology study. All 5 had the BRCA1 185 del-AG mutation. Three of the 5 malignancies originated from the ovaries and 2 in the fallopian tubes with no involvement of the ovaries. CONCLUSIONS: A 5.4% incidence of early occult malignancy in adnexal pathology of BSO was found in carriers of Ashkenazi Jewish BRCA mutations. Two cases with malignant origins within the fallopian tube, while sparing the ovaries in their entirety, support the fallopian tubes as the originating organ for some ovarian or peritoneal malignancies in BRCA mutation carriers.

Mammographic density and breast cancer in women from high risk families.

INTRODUCTION: Mammographic density (MD) is one of the strongest determinants of sporadic breast cancer (BC). In this study, we compared MD in BRCA1/2 mutation carriers and non-carriers from BRCA1/2 mutation-positive families and investigated the association between MD and BC among BRCA1/2 mutation carriers per type of mutation and tumor subtype. METHODS: The study was carried out in 1039 female members of BRCA1 and BRCA2 mutation-positive families followed at 16 Spanish Genetic Counseling Units. Participants' density was scored retrospectively from available mammograms by a single blinded radiologist using a 5-category scale (<10 %, 10-25 %, 25-50 %, 50-75 %, >75 %). In BC cases, we selected mammograms taken prior to diagnosis or from the contralateral breast, whereas, in non-cases, the last screening mammogram was evaluated. MD distribution in carriers and non-carriers was compared using ordinal logistic models, and the association between MD and BC in BRCA1/2 mutation carriers was studied using logistic regression. Huber-White robust estimators of variance were used to take into account correlations between family members. A similar multinomial model was used to explore this association by BC subtype. RESULTS: We identified and scored mammograms from 341 BRCA1, 350 BRCA2 mutation carriers and 229 non-carriers. Compared to non-carriers, MD was significantly lower among BRCA2 mutation carriers (odds ratio (OR) =0.71; P-value=0.04), but not among BRCA1 carriers (OR=0.84; P-value=0.33). MD was associated with subsequent development BC (OR per category of MD=1.45; 95 % confidence interval=1.18-1.78, P-value<0.001), with no significant differences between BRCA1 and BRCA2 mutation carriers (P-value=0.48). Finally, no statistically significant differences were observed in the association of MD with specific BC subtypes. CONCLUSIONS: Our study, the largest to date on this issue, confirms that MD is an independent risk factor for all BC subtypes in either BRCA1 and BRCA2 mutation carriers, and should be considered a phenotype risk marker in this context.

Heterozygous mutations in the PALB2 hereditary breast cancer predisposition gene impact on the three-dimensional nuclear organization of patient-derived cell lines.

PALB2/FANCN is a BRCA1- and BRCA2-interacting Fanconi Anemia (FA) protein crucial for key BRCA2 genome caretaker functions. Heterozygous germline mutations in PALB2 predispose to breast cancer and biallelic mutations cause FA. FA proteins play a critical role in the telomere maintenance pathway, with telomeric shortening observed in FA cells. Less is known about telomere maintenance in the heterozygous state. Here, we investigate the roles of PALB2 heterozygous mutations in genomic instability, an important carcinogenesis precursor. Patient-derived lymphoblastoid (LCL) and fibroblast (FCL) cell lines with monoallelic truncating PALB2 mutations were investigated using a combination of molecular imaging techniques including centromeric FISH, telomeric Q-FISH and spectral karyotyping (SKY). Mitomycin C and Cisplatin sensitivity was assayed via cellular metabolism of WST-1. The PALB2 c.229delT FCL showed increases in telomere counts associated with increased mean intensity compared with two wild-type FCLs generated from first-degree relatives (P =1.04E-10 and P =9.68E-15) and it showed evidence of chromosomal rearrangements. Significant differences in centromere distribution were observed in one of three PALB2 heterozygous FCLs analyzed when compared with PALB2 wild-type, BRCA1 and BRCA2 heterozygous FCLs. No significant consistently increased sensitivity to Mitomycin C or Cisplatin was observed in LCLs. Our results are suggestive of an altered centromere distribution profile and a telomere instability phenotype. Together, these may indicate critical nuclear organization defects associated with the predisposition to transformation and early stage development of PALB2-related cancers.