High-risk Breast Cancer Families Research Articles

Germline RAD51C and RAD51D Mutations in High-Risk Chinese Breast and/or Ovarian Cancer Patients and Families.

RAD51C and RAD51D are crucial in homologous recombination (HR) DNA repair. The prevalence of the RAD51C and RAD51D mutations in breast cancer varies across ethnic groups. Associations of RAD51C and RAD51D germline pathogenic variants (GPVs) with breast and ovarian cancer predisposition have been recently reported and are of interest. We performed multi-gene panel sequencing to study the prevalence of RAD51C and RAD51D germline mutations among 3728 patients with hereditary breast and/or ovarian cancer (HBOC). We identified 18 pathogenic RAD51C and RAD51D mutation carriers, with a mutation frequency of 0.13% (5/3728) and 0.35% (13/3728), respectively. The most common recurrent mutation was RAD51D c.270_271dupTA; p.(Lys91Ilefs*13), with a mutation frequency of 0.30% (11/3728), which was also commonly identified in Asians. Only four out of six cases (66.7%) of this common mutation tested positive for homologous recombination deficiency (HRD). Taking the family studies in our registry and tumor molecular pathology together, we concluded that this relatively common RAD51D variant showed incomplete penetrance in our local Chinese community. Personalized genetic counseling emphasizing family history for families with this variant, as suggested at the UK Cancer Genetics Group (UKCGG) Consensus meeting, would also be appropriate in Chinese families.

A cost-utility analysis of BRCA1 and BRCA2 testing in high-risk breast cancer patients and family members in Thailand: a cost-effective policy in resource-limited settings.

Screening for germline pathogenic BRCA1 or BRCA2 variants (gBRCA) in high-risk breast cancer patients is known to be cost-effective in high-income countries. Nationwide adoption of genetics testing in high-risk breast cancer population remains poor. Our study aimed to assess gBRCA health economics data in the middle-income country setting of Thailand. Decision tree and Markov model were utilized to assess cost-utility between the testing vs. no-testing groups from a societal and lifetime perspective and lifetime. We interviewed 264 patients with breast/ovarian cancer and their family members to assess relevant costs and quality of life using EQ-5D-5L. One-way sensitivity, probabilistic sensitivity (Monte Carlo simulation), and budget impact analyses were done to estimate the outcome under Thailand's Universal Health Coverage scheme. The predicted lifetime cost and Quality-adjusted Life Years (QALY) for those with breast cancer were $13,788 and 10.22 in the testing group and $13,702 and 10.07 in the no-testing group. The incremental cost-effectiveness ratio for gBRCA testing in high-risk breast cancer patients was $573/QALY. The lifetime cost for the family members of those with gBRCA was $14,035 (QALY 9.99), while the no-testing family members group was $14,077 (QALY 9.98). Performing gBRCA testing in family members was cost-saving. Cost-utility analysis demonstrated a cost-effective result of gBRCA testing in high-risk breast cancer patients and cost-saving in familial cascade testing. The result was endorsed in the national health benefits package in 2022. Other middle-income countries may observe the cost-effective/cost-saving aspects in common genetic diseases under their national health schemes.

Communication processes about predictive genetic testing within high-risk breast cancer families: a two-phase study design

The detection of a pathogenic variant in the BRCA1 or BRCA2 gene has medical and psychological consequences for both, affected mutation carriers and their relatives. A two-phase study with explanatory sequential mixed methods design examined the psychological impact of genetic testing and associated family communication processes. Analyzing a survey data of 79 carriers of a BRCA1 or BRCA2 mutation, the majority had general psychological distress independent of cancer diagnosis in the patients’ history. The point prevalence of depression was 16.9%. Contrary to their subjective perception, the respondents’ knowledge about those mutations was moderate. Despite the high rate of information transfer to relatives at risk (100%), their reported uptake of genetic testing was low (45.6%). Communication about the mutation detection was more frequent with female than with male relatives. In-depth focus group interviews revealed significant barriers to accessing genetic counseling including anxiety, uncertainty about the benefits of testing and about the own cancer risk, particularly among males. This study suggests that an adequate knowledge of the genetic background and psychological support is required to reduce emotional distress, to support familial communication and to facilitate genetic testing.

Identification of BRCA2 Cis Double Heterozygous Breast Cancer Cases Using Whole Exome Sequencing: Phenotypic Expression and Impact on Personalized Oncology.

BRCA1 and BRCA2 are the most commonly mutated breast cancer susceptibility genes that convey a high risk of breast and ovarian cancer. Most BRCA1 or BRCA2 mutation carriers have inherited a single heterozygous mutation. In recent years, very rare cases with biallelic or trans double heterozygous mutations on BRCA1 and or BRCA2 have been identified and seem to be associated with distinctive phenotypes. Given that this genotype-phenotype correlation in cancer predisposing hereditary conditions is of relevance for oncological prevention and genetic testing, it is important to investigate these rare BRCA genotypes for better clinical management of BRCA mutation carriers. Here we present the first report on Cis double heterozygosity (Cis DH) on BRCA2 gene identified using Whole exome sequencing (WES) in a Tunisian family with two BRCA2 mutations namely: c.632-1G>A and c.1310_1313DelAAGA that are both reported as pathogenic in ClinVar database. Subsequent analysis in 300 high-risk Tunisian breast cancer families detected this Cis double heterozygous genotype in 8 additional individuals belonging to 5 families from the same geographic origin suggesting a founder effect. Moreover, the observed Cis DH seems to be associated with an early age of onset (mean age = 35.33 years) and severe phenotype of the disease with high breast cancer grade and multiple cancer cases in the family. The identification of unusual BRCA genotypes in this Tunisian cohort highlights the importance of performing genetic studies in under-investigated populations. This will also potentially help avoiding erroneous classifications of genetic variants in African population and therefore avoiding clinical misdiagnosis of BRCA related cancers. Our findings will also have an impact on the genetic testing and the clinical management of North African breast cancer patients as well as patients from different other ethnic groups in regard to several emerging target therapies such as PARP inhibitors.

Investigation of monogenic causes of familial breast cancer: data from the BEACCON case-control study

Breast cancer (BC) has a significant heritable component but the genetic contribution remains unresolved in the majority of high-risk BC families. This study aims to investigate the monogenic causes underlying the familial aggregation of BC beyond BRCA1 and BRCA2, including the identification of new predisposing genes. A total of 11,511 non-BRCA familial BC cases and population-matched cancer-free female controls in the BEACCON study were investigated in two sequencing phases: 1303 candidate genes in up to 3892 cases and controls, followed by validation of 145 shortlisted genes in an additional 7619 subjects. The coding regions and exon–intron boundaries of all candidate genes and 14 previously proposed BC genes were sequenced using custom designed sequencing panels. Pedigree and pathology data were analysed to identify genotype-specific associations. The contribution of ATM, PALB2 and CHEK2 to BC predisposition was confirmed, but not RAD50 and NBN. An overall excess of loss-of-function (LoF) (OR 1.27, p = 9.05 × 10−9) and missense (OR 1.27, p = 3.96 × 10−73) variants was observed in the cases for the 145 candidate genes. Leading candidates harbored LoF variants with observed ORs of 2–4 and individually accounted for no more than 0.79% of the cases. New genes proposed by this study include NTHL1, WRN, PARP2, CTH and CDK9. The new candidate BC predisposition genes identified in BEACCON indicate that much of the remaining genetic causes of high-risk BC families are due to genes in which pathogenic variants are both very rare and convey only low to moderate risk.

Identification of Novel BRCA1 and RAD50 Mutations Associated With Breast Cancer Predisposition in Tunisian Patients.

BackgroundDeleterious mutations on BRCA1/2 genes are known to confer high risk of developing breast and ovarian cancers. The identification of these mutations not only helped in selecting high risk individuals that need appropriate prevention approaches but also led to the development of the PARP-inhibitors targeted therapy. This study aims to assess the prevalence of the most frequent BRCA1 mutation in Tunisia, c.211dupA, and provide evidence of its common origin as well as its clinicopathological characteristics. We also aimed to identify additional actionable variants using classical and next generation sequencing technologies (NGS) which would allow to implement cost-effective genetic testing in limited resource countries.Patients and MethodsUsing sanger sequencing, 112 breast cancer families were screened for c.211dupA. A set of patients that do not carry this mutation were investigated using NGS. Haplotype analysis was performed to assess the founder effect and to estimate the age of this mutation. Correlations between genetic and clinical data were also performed.ResultsThe c.211dupA mutation was identified in 8 carriers and a novel private BRCA1 mutation, c.2418dupA, was identified in one carrier. Both mutations are likely specific to North-Eastern Tunisia. Haplotype analysis supported the founder effect of c.211dupA and showed its recent origin. Phenotype-genotype correlation showed that both BRCA1 mutations seem to be associated with a severe phenotype. Whole Exome Sequencing (WES) analysis of a BRCA negative family revealed a Variant of Unknown Significance, c.3647C > G on RAD50. Molecular modeling showed that this variant could be classified as deleterious as it is responsible for destabilizing the RAD50 protein structure. Variant prioritization and pathway analysis of the WES data showed additional interesting candidate genes including MITF and ANKS6.ConclusionWe recommend the prioritization of BRCA1-c.211dupA screening in high risk breast cancer families originating from the North-East of Tunisia. We also highlighted the importance of NGS in detecting novel mutations, such as RAD50-c.3647C > G. In addition, we strongly recommend using data from different ethnic groups to review the pathogenicity of this variant and reconsider its classification in ClinVar.

Under-ascertainment of breast cancer susceptibility gene carriers in a cohort of New Zealand female breast cancer patients

BackgroundDiagnostic screening for pathogenic variants in breast cancer susceptibility genes, including BRCA1, BRCA2, PALB2, PTEN and TP53, may be offered to New Zealanders from suspected high-risk breast (and ovarian) cancer families. However, it is unknown how many high-risk pathogenic variant carriers in New Zealand are not offered genetic screening using existing triage tools and guidelines for breast (and ovarian) cancer patients.MethodsPanel-gene sequencing of the coding and non-coding regions of the BRCA1 and BRCA2 genes, and the coding regions and splice sites of CDH1, PALB2, PTEN and TP53, was undertaken for an unselected cohort of 367 female breast cancer patients. A total of 1685 variants were evaluated using the ENIGMA and the ACMG/AMP variant classification guidelines.ResultsOur study identified that 13 (3.5%) breast cancer patients carried a pathogenic or likely pathogenic variant in BRCA1, BRCA2, PALB2, or PTEN. A significantly higher number of pathogenic variant carriers had grade 3 tumours (10/13) when compared to non-carriers; however, no other clinicopathological characteristics were found to be significantly different between (likely) pathogenic variant carriers and non-carriers, nor between variant of unknown significance carriers and non-carriers. Notably, 46% of the identified (likely) pathogenic variant carriers had not been referred for a genetic assessment and consideration of genetic testing.ConclusionOur study shows a potential under-ascertainment of women carrying a (likely) pathogenic variant in a high-risk breast cancer susceptibility gene. These results suggest that further research into testing pathways for New Zealand breast cancer patients may be required to reduce the impact of hereditary cancer syndromes for these individuals and their families.

Targeting SMYD3 to Sensitize Homologous Recombination-Proficient Tumors to PARP-Mediated Synthetic Lethality.

SummarySMYD3 is frequently overexpressed in a wide variety of cancers. Indeed, its inactivation reduces tumor growth in preclinical in vivo animal models. However, extensive characterization in vitro failed to clarify SMYD3 function in cancer cells, although confirming its importance in carcinogenesis. Taking advantage of a SMYD3 mutant variant identified in a high-risk breast cancer family, here we show that SMYD3 phosphorylation by ATM enables the formation of a multiprotein complex including ATM, SMYD3, CHK2, and BRCA2, which is required for the final loading of RAD51 at DNA double-strand break sites and completion of homologous recombination (HR). Remarkably, SMYD3 pharmacological inhibition sensitizes HR-proficient cancer cells to PARP inhibitors, thereby extending the potential of the synthetic lethality approach in human tumors.

Tumor sequencing is useful to refine the analysis of germline variants in unexplained high-risk breast cancer families

BackgroundMultigene panels are routinely used to assess for predisposing germline mutations in families at high breast cancer risk. The number of variants of unknown significance thereby identified increases with the number of sequenced genes. We aimed to determine whether tumor sequencing can help refine the analysis of germline variants based on second somatic genetic events in the same gene.MethodsWhole-exome sequencing (WES) was performed on whole blood DNA from 70 unrelated breast cancer patients referred for genetic testing and without a BRCA1, BRCA2, TP53, or CHEK2 mutation. Rare variants were retained in a list of 735 genes. WES was performed on matched tumor DNA to identify somatic second hits (copy number alterations (CNAs) or mutations) in the same genes. Distinct methods (among which immunohistochemistry, mutational signatures, homologous recombination deficiency, and tumor mutation burden analyses) were used to further study the role of the variants in tumor development, as appropriate.ResultsSixty-eight patients (97%) carried at least one germline variant (4.7 ± 2.0 variants per patient). Of the 329 variants, 55 (17%) presented a second hit in paired tumor tissue. Of these, 53 were CNAs, resulting in tumor enrichment (28 variants) or depletion (25 variants) of the germline variant. Eleven patients received variant disclosure, with clinical measures for five of them. Seven variants in breast cancer-predisposing genes were considered not implicated in oncogenesis. One patient presented significant tumor enrichment of a germline variant in the oncogene ERBB2, in vitro expression of which caused downstream signaling pathway activation.ConclusionTumor sequencing is a powerful approach to refine variant interpretation in cancer-predisposing genes in high-risk breast cancer patients. In this series, the strategy provided clinically relevant information for 11 out of 70 patients (16%), adapted to the considered gene and the familial clinical phenotype.

Family Study Designs Informed by Tumor Heterogeneity and Multi-Cancer Pleiotropies: The Power of the Utah Population Database.

Previously, family-based designs and high-risk pedigrees have illustrated value for the discovery of high- and intermediate-risk germline breast cancer susceptibility genes. However, genetic heterogeneity is a major obstacle hindering progress. New strategies and analytic approaches will be necessary to make further advances. One opportunity with the potential to address heterogeneity via improved characterization of disease is the growing availability of multisource databases. Specific to advances involving family-based designs are resources that include family structure, such as the Utah Population Database (UPDB). To illustrate the broad utility and potential power of multisource databases, we describe two different novel family-based approaches to reduce heterogeneity in the UPDB. Our first approach focuses on using pedigree-informed breast tumor phenotypes in gene mapping. Our second approach focuses on the identification of families with similar pleiotropies. We use a novel network-inspired clustering technique to explore multi-cancer signatures for high-risk breast cancer families. Our first approach identifies a genome-wide significant breast cancer locus at 2q13 [P = 1.6 × 10-8, logarithm of the odds (LOD) equivalent 6.64]. In the region, IL1A and IL1B are of particular interest, key cytokine genes involved in inflammation. Our second approach identifies five multi-cancer risk patterns. These clusters include expected coaggregations (such as breast cancer with prostate cancer, ovarian cancer, and melanoma), and also identify novel patterns, including coaggregation with uterine, thyroid, and bladder cancers. Our results suggest pedigree-informed tumor phenotypes can map genes for breast cancer, and that various different cancer pleiotropies exist for high-risk breast cancer pedigrees. Both methods illustrate the potential for decreasing etiologic heterogeneity that large, population-based multisource databases can provide.See all articles in this CEBP Focus section, "Modernizing Population Science."

Abstract P5-03-03: Tumor sequencing is useful to reclassify germline variants in unexplained high-risk breast cancer families

Abstract BACKGROUND Multigene panels are routinely used to search for predisposing mutations in families considered at high risk of breast cancer. The number of variants of unknown significance (VUS) thereby identified increases with the number of sequenced genes. We aimed to determine whether tumor sequencing can help reclassify germline VUS based on second events hitting the same gene. METHODS Whole-exome sequencing (WES) was performed on whole-blood DNA from 70 unrelated breast cancer patients referred for genetic testing and without BRCA1, BRCA2, TP53 or CHEK2 mutations. Rare variants considered as a VUS based on ACMG guidelines were retained in a list of 735 genes. WES was performed on matched tumor DNA to look for somatic second hits (copy number alteration or second mutation) in the same genes. RESULTS Sixty-eight patients (97%) carried at least one germline VUS (4.7 ± 2.0 variants per patient). Of the 329 VUS, 55 (17%) presented a somatic second hit in the paired tumor tissue. Two were a second somatic mutation, whereas 53 were copy number alterations. This resulted in relative tumor enrichment or depletion of the germline variant for 28 and 25 VUS, respectively. Estimation of tumor mutation burden and homologous recombination deficiency through mutational signatures and allelic imbalance analysis could highlight bi-allelic gene inactivation in relevant cases. Clinical measures were proposed for six patients carrying a germline variant on PALB2, PMS2, PMS1, MUTYH or NTHL1. Variant disclosure without clinical measures was proposed for five patients carrying a variant on MRE11A, ATM, WRN or TP53 (functional testing ongoing for the latter). Germline and tumor DNA analysis of an affected relative of the patient carrying the germline MRE11A variant demonstrated the co-segregation of the variant as well as the presence of the same somatic second hit. Seven VUS on clinically actionable breast cancer predisposing genes (PALB2, BRCA2, CDH1, ATM and BARD1) were downgraded to probably benign variants as the germline variant was depleted in the tumor. One patient presented a significant tumor enrichment of a germline VUS in the C-terminal domain of the oncogene ERBB2. In vitro expression of this variant caused downstream signaling pathway activation. CONCLUSION Tumor sequencing is a powerful approach to refine VUS in cancer-predisposing genes in high-risk breast cancer patients. In this series, the strategy provided clinically relevant information for 11 out of 70 patients (16%). Citation Format: Cedric Van Marcke, Raphaël Helaers, Céline A Schoonjans, Martine Berlière, Anne De Leener, Jean-Luc Canon, Peter Vuylsteke, Jean-Pascal Machiels, Nisha Limaye, Miikka Vikkula, Francois P Duhoux. Tumor sequencing is useful to reclassify germline variants in unexplained high-risk breast cancer families [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-03-03.

The Effect of Prior Comparison MRI on Interpretive Performance of Screening Breast MRI.

To evaluate the effect of prior comparison MRI on interpretive performance of screening breast MRI. After institutional review board approval, all screening breast MRI examinations performed from January 2011 through December 2014 were retrospectively reviewed. Screening performance metrics were estimated and compared for exams with and without a prior comparison MRI, using logistic regression models to adjust for age and screening indication (BRCA mutation or thoracic radiation versus breast cancer history versus high-risk lesion history versus breast cancer family history). Most exams, 4509 (87%), had a prior comparison MRI (incidence round), while 661 (13%) did not (prevalence round). Abnormal interpretation rate (6% vs 20%, P < 0.01), biopsy rate (3% vs 9%, P < 0.01), and false-positive biopsy recommendation rate per 1000 exams (21 vs 71, P < 0.01) were significantly lower in the incidence rounds compared to the prevalence rounds, while specificity was significantly higher (95% vs 81%, P < 0.01). There was no difference in cancer detection rate (CDR) per 1000 exams (12 vs 20, P = 0.1), positive predictive value of biopsies performed (PPV3) (35% vs 23%, P = 0.1), or sensitivity (86% vs 76%, P = 0.4). Presence of a prior comparison significantly improves incidence round screening breast MRI examination performance compared with prevalence round screening. Consideration should be given to updating the BI-RADS breast MRI screening benchmarks and auditing prevalence and incidence round examinations separately.

Targeting SMYD3 to Sensitize Homologous Recombination-Proficient Tumors to PARP-Mediated Synthetic Lethality

SMYD3 is frequently overexpressed in a wide variety of cancers. Indeed, its inactivation reduces tumor growth in preclinical in vivo animal models. However, extensive characterization in vitro failed to clarify SMYD3 function in cancer cells, although confirming its importance in carcinogenesis. Taking advantage of a SMYD3 mutant variant identified in a high-risk breast cancer family, here we show that SMYD3 phosphorylation by ATM enables the formation of a multiprotein complex including ATM, SMYD3, CHK2, and BRCA2, which is required for the final loading of RAD51 at DNA double-strand break sites and completion of homologous recombination (HR). Remarkably, SMYD3 pharmacological inhibition sensitizes HR-proficient cancer cells to PARP inhibitors, thereby extending the potential of the synthetic lethality approach in human tumors.

Mutational analysis of BRCA1 and BRCA2 in northwest Chinese breast cancer patients

Background: BRCA1 and BRCA2 are the most well-known susceptibility genes in breast cancer, indicating high-risk breast cancer families and influencing both treatment options. However, data of BRCA mutation in Chinese breast cancer population was limited. Here we explored the BRCA1/2 mutation status and analyzed their clinicopathological relationships among breast cancer patients with high hereditary risk in northwest China. Methods: Breast cancer patients admitted to Xijing Hospital, between November 2015 and May 2016, with high hereditary risk were recruited. Fresh peripheral venous blood samples were collected for BRCA1/2 gene screening. Risk factors for BRCA1/2 mutations were studied via single-factor analysis and multivariable logistic analysis. Furthermore, we reviewed the literature and discussed the possible mechanism of the mutant genome types. Results: Eighty-two patients were enrolled in the study. Twenty (24.4%) of them were found with BRCA1/2 mutation, including 8 BRCA1 mutation and 13 BRCA2 mutation. BRCA1 and BRCA2 co-mutation was observed in only one case. The mutant genome types included pathogenic variant (4/82), potential pathogenic variant (4/82), beneficial mutations (8/82), and chemotherapy sensitivity-related mutations (5/82). Prognosis-related mutations were enriched in BRCA2 gene, while drug-sensitive related mutations were always observed in BRCA1 gene. Multiple logistic analysis showed that HER2 [odds ratio (OR) 4.58; 95% confidence interval (CI), 1.182–17.74; P=0.028) might be independent factor for BRCA1/2 mutation. Conclusions: The incidence and feature of BRCA1/2 mutation in our center was similar to that in other regions. HER2 expression was independent factor for BRCA1 and BRCA2 mutation. BRCA2 T/-, BRCA2 A/-, BRCA2 G/- and BRCA2 C/-mutation subtypes might be potential harmful mutations for Chinese breast cancer population.

BRCA1 and BRCA2 mutations in a sample of breast and ovarian cancer families from the Colombian pacific.

Introduction: Breast cancer is the most common neoplasia of women from all over the world especially women from Colombia. 5%­10% of all cases are caused by hereditary factors, 25% of those cases have mutations in the BRCA1/BRCA2 genes. Objective: The purpose of this study was to identify the mutations associated with the risk of familial breast and/or ovarian cancer in a population of Colombian pacific. Methods: 58 high-risk breast and/or ovarian cancer families and 20 controls were screened for germline mutations in BRCA1 and BRCA2, by Single Strand Conformation Polymorphism (SSCP) and sequencing. Results: Four families (6.9%) were found to carry BRCA1 mutations and eight families (13.8%) had mutations in BRCA2. In BRCA1, we found three Variants of Uncertain Significance (VUS), of which we concluded, using in silico tools, that c.81­12C>G and c.3119G>A (p.Ser1040Asn) are probably deleterious, and c.3083G>A (p.Arg1028His) is probably neutral. In BRCA2, we found three variants of uncertain significance: two were previously described and one novel mutation. Using in silico analysis, we concluded that c.865A>G (p.Asn289Asp) and c.6427T>C (p.Ser2143Pro) are probably deleterious and c.125A>G (p.Tyr42Cys) is probably neutral. Only one of them has previously been reported in Colombia. We also identified 13 polymorphisms (4 in BRCA1 and 9 in BRCA2), two of them are associated with a moderate increase in breast cancer risk (BRCA2 c.1114A>C and c.8755­66T>C). Conclusion: According to our results, the Colombian pacific population presents diverse mutational spectrum for BRCA genes that differs from the findings in other regions in the country.

Mutational analysis of BRCA1 and BRCA2 in northwest Chinese breast cancer patients.

BackgroundBRCA1 and BRCA2 are the most well-known susceptibility genes in breast cancer, indicating high-risk breast cancer families and influencing both treatment options. However, data of BRCA mutation in Chinese breast cancer population was limited. Here we explored the BRCA1/2 mutation status and analyzed their clinicopathological relationships among breast cancer patients with high hereditary risk in northwest China.MethodsBreast cancer patients admitted to Xijing Hospital, between November 2015 and May 2016, with high hereditary risk were recruited. Fresh peripheral venous blood samples were collected for BRCA1/2 gene screening. Risk factors for BRCA1/2 mutations were studied via single-factor analysis and multivariable logistic analysis. Furthermore, we reviewed the literature and discussed the possible mechanism of the mutant genome types.ResultsEighty-two patients were enrolled in the study. Twenty (24.4%) of them were found with BRCA1/2 mutation, including 8 BRCA1 mutation and 13 BRCA2 mutation. BRCA1 and BRCA2 co-mutation was observed in only one case. The mutant genome types included pathogenic variant (4/82), potential pathogenic variant (4/82), beneficial mutations (8/82), and chemotherapy sensitivity-related mutations (5/82). Prognosis-related mutations were enriched in BRCA2 gene, while drug-sensitive related mutations were always observed in BRCA1 gene. Multiple logistic analysis showed that HER2 [odds ratio (OR) 4.58; 95% confidence interval (CI), 1.182–17.74; P=0.028) might be independent factor for BRCA1/2 mutation.ConclusionsThe incidence and feature of BRCA1/2 mutation in our center was similar to that in other regions. HER2 expression was independent factor for BRCA1 and BRCA2 mutation. BRCA2 T/-, BRCA2 A/-, BRCA2 G/- and BRCA2 C/-mutation subtypes might be potential harmful mutations for Chinese breast cancer population.

Addition of a 161-SNP polygenic risk score to family history-based risk prediction: impact on clinical management in non-BRCA1/2 breast cancer families

BackgroundThe currently known breast cancer-associated single nucleotide polymorphisms (SNPs) are presently not used to guide clinical management. We explored whether a genetic test that incorporates a SNP-based polygenic risk score...

PO-206 Modelling T cell acute lymphoblastic leukaemia using CRISPR/Cas9 mediated genome editing in Xenopus tropicalis

IntroductionThe helicase BRIP1 is critically required for genomic maintenance, and BRIP1 helicase deficient germline variants are associated with Fanconi Anaemia (bi-allelic) and various cancers (mono-allelic), in particular ovarian and breast cancer. Cellular based assays and biochemical studies have elucidated the function of BRIP1 in replication stress responses, including interaction partners and enzymatic substrate specificity. However, functional characterisation of BRIP1 for these processes in vivo are largely unexplored, including the importance of BRIP1 as a tumour suppressor for breast cancer, and therapy responses. This project aims to elucidate the functional roles of BRIP1 as a tumour suppressor for breast cancer and in therapy responses.Material and methodsWe have developed breast tissue-specific knockout mice for BRIP1, and will monitor the development of breast tumours. In addition, we have developed mice deficient for BRIP1 helicase activity (K52R) to further investigate the functional role of BRIP1 as a tumour suppressor. In addition, we will use the mouse models for intervention studies, testing known and novel therapies for BRIP1 deficient breast cancer. Moreover, we will investigate BRIP1 germline variants identified in high-risk breast cancer families by large scale sequencing efforts. This comprehensive list of patient derived mutations will be introduced endogenously in a primary epithelial cell line using a CRISPR-CAS9 approach. To monitor the effect on BRIP1 activity, these cell lines will be tested in cancer relevant functional assays for which BRIP1 deficient cells are known to have a phenotype.Results and discussionsThis project is at an early stage, and we will present our preliminary data from our BRIP1 mouse models, and from our in vitro CRISPR assay for testing BRIP1 gene variants of uncertain significance (VUS).ConclusionThis project is expected to yield novel insight into the regulation of critical genomic stability pathways and provide important knowledge for developing improved germ line variant risk prediction and treatment opportunities for patients.

Abstract 1245: Identification of germline variants in cancer susceptibility genes in patients with hereditary breast and ovarian cancer syndrome by massive parallel sequencing in Argentinean population

Abstract Breast cancer is the most frequent cancer and ovarian cancer the seventh most frequent cancer among females worldwide, representing approximately 25% and 4% of all cancers. In Argentina, breast cancer and Ovarian cancer cause 6163 and 1332 deaths per year, respectively. Both breast and ovarian cancers are heterogeneous diseases composed of different tumor types with distinctive features and behaviors. The main risk factors for breast and ovarian cancer include age, family history, and genetics.The genetic components of both of the diseases have been well established, contributing to up to 10% of all breast cancer cases and 15% of all ovarian cancer cases.The two major susceptibility genes for both diseases are BRCA1 and BRCA2, and several other susceptibility genes have been identified. However, in the majority of high-risk breast and/or ovarian cancer (HBOC) families, the genetic predisposition factors remain unidentified, making the genetic counseling of these families challenging. The aim of the current study is to utilize an NGS approach to identify genetic factors that predispose individuals to hereditary breast and/or ovarian cancer (HBOC) in the high-risk Argentinian BRCA1/2 mutation-negative HBOC patients.16 patients were analyzed, the DNA was extracted from a blood samples and was subjected to a targeted massively parallel sequencing platform comprising 141 cancer predisposition genes. We detected in these patient 6 pathogenic variants in SBDS, FANCA, MC1R, WRN, MSR1 and SDHD genes. The effect of these variants are of type: non-synonymous (67%) and stop codon gains (33%). We also found 6 variants of uncertain significance (VUS) in APC, RAD50, SDHB, FANCD2, MLH1 and CDH1 genes.In conclusion, the identification of new variants could help to discover new genes associated to HBOC in the population of Argentina.These findings provide an excellent premise for further studies and could be utilized in the design of more efficient clinical management strategies for HBOC. Citation Format: Alejandra Franco, Fernando Orti, Sandra Perdomo, Cecilia Riggi, Cecilia Frecha, Javier Oliver. Identification of germline variants in cancer susceptibility genes in patients with hereditary breast and ovarian cancer syndrome by massive parallel sequencing in Argentinean population [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1245.

PO-205 Functional characterisation of BRIP1/FANCJ in tumour suppression and therapy response

Introduction The helicase BRIP1 is critically required for genomic maintenance, and BRIP1 helicase deficient germline variants are associated with Fanconi Anaemia (bi-allelic) and various cancers (mono-allelic), in particular ovarian and breast cancer. Cellular based assays and biochemical studies have elucidated the function of BRIP1 in replication stress responses, including interaction partners and enzymatic substrate specificity. However, functional characterisation of BRIP1 for these processes in vivo are largely unexplored, including the importance of BRIP1 as a tumour suppressor for breast cancer, and therapy responses. This project aims to elucidate the functional roles of BRIP1 as a tumour suppressor for breast cancer and in therapy responses. Material and methods We have developed breast tissue-specific knockout mice for BRIP1, and will monitor the development of breast tumours. In addition, we have developed mice deficient for BRIP1 helicase activity (K52R) to further investigate the functional role of BRIP1 as a tumour suppressor. In addition, we will use the mouse models for intervention studies, testing known and novel therapies for BRIP1 deficient breast cancer. Moreover, we will investigate BRIP1 germline variants identified in high-risk breast cancer families by large scale sequencing efforts. This comprehensive list of patient derived mutations will be introduced endogenously in a primary epithelial cell line using a CRISPR-CAS9 approach. To monitor the effect on BRIP1 activity, these cell lines will be tested in cancer relevant functional assays for which BRIP1 deficient cells are known to have a phenotype. Results and discussions This project is at an early stage, and we will present our preliminary data from our BRIP1 mouse models, and from our in vitro CRISPR assay for testing BRIP1 gene variants of uncertain significance (VUS). Conclusion This project is expected to yield novel insight into the regulation of critical genomic stability pathways and provide important knowledge for developing improved germ line variant risk prediction and treatment opportunities for patients.