Prevalence of nonfounder BRCA1/2 mutations in Ashkenazi Jewish patients presenting for genetic testing at a hereditary breast and ovarian cancer center

Germline variants associated with breast cancer in Khakass women of North Asia

INTRODUCTION

Variants in the BRCA1/2 genes are responsible for familial breast cancer. Numerous studies showed a different spectrum of BRCA variants among breast cancer patients of different Ethnicity origin. In the available literature, no previous research has focused on breast cancer-associated variants among the Khakass people (the indigenous people of the Russian Federation).

METHODS

Twenty-six Khakass breast cancer patients were enrolled in the study. Genomic DNA was isolated from blood samples and used to prepare libraries using a Hereditary Cancer Solution kit. Next-generation sequencing (NGS) was performed using the MiSeq System (Illumina, USA).

RESULTS

In our study, 12% of patients (3/26) carried a single pathogenic variant; 54% of patients (14/26) carried variants of uncertain significance (VUS) or conflicting variants; and 35% of patients (9/26) did not carry any clinically significant variants. Germline pathogenic variant in the ATM gene (rs780619951, NC_000011.10:g.108259022C > T) was identified in two unrelated patients with a family history of cancer (7.6%, 2/26). The pathogenic truncating variant in the ATM gene (p. R805* or c.2413C > T) leads to the nonfunctional version of the protein. This variant has been earlier reported in individuals with a family history of breast cancer.

CONCLUSIONS

Our pilot study describes the germline variant in the ATM gene associated with breast cancer in Khakass women of North Asia.

Gynecologic Cancer Risk and Genetics: Informing an Ideal Model of Gynecologic Cancer Prevention

Individuals with proven hereditary cancer syndrome (HCS) such as BRCA1 and BRCA2 have elevated rates of ovarian, breast, and other cancers. If these high-risk people can be identified before a cancer is diagnosed, risk-reducing interventions are highly effective and can be lifesaving. Despite this evidence, the vast majority of Canadians with HCS are unaware of their risk. In response to this unmet opportunity for prevention, the British Columbia Gynecologic Cancer Initiative convened a research summit “Gynecologic Cancer Prevention: Thinking Big, Thinking Differently” in Vancouver, Canada on 26 November 2021. The aim of the conference was to explore how hereditary cancer prevention via population-based genetic testing could decrease morbidity and mortality from gynecologic cancer. The summit invited local, national, and international experts to (1) discuss how genetic testing could be more broadly implemented in a Canadian system, (2) identify key research priorities in this topic and (3) outline the core essential elements required for such a program to be successful. This report summarizes the findings from this research summit, describes the current state of hereditary genetic programs in Canada, and outlines incremental steps that can be taken to improve prevention for high-risk Canadians now while developing an organized population-based hereditary cancer strategy.

Germline Mutational Landscape in Chinese Patients With Advanced Breast Cancer

Background

Genetic testing for breast cancer (BC) patients may shift the paradigm towards more personalized management and treatment strategies. While gene alterations may be ethnic-specific in breast cancer, our understanding of genetic epidemiology of BC remains mainly driven by data from Caucasian populations and further limited to selected handful of genes.

Methods

We collected whole blood samples from 356 BC patients at metastatic first line BC and primary stage IV disease at Beijing Cancer Hospital between Jan. 2013 to Dec. 2019. A comprehensive 600-gene cancer panel was used to detect germline variants in the covered genes with a median 300x sequencing depth. Variants were classified into pathogenic, likely pathogenic, variant of uncertain significance, likely benign and benign groups according to the ACMG/AMP Standards and Guidelines. Pathogenic and likely pathogenic variants were considered as deleterious mutations.

Results

The median age of 356 BC patients was 49 years (range, 21-87 years) at the first diagnosis of BC. Deleterious germline mutations across 48 cancer-related genes were identified in 21.6% (77/356) of the patients. The most prevalent mutations were BRCA1/2 mutations (7.0%), followed by ATM and RAD50 mutations (1.4% each). In addition, patients with family history were more likely to carry BRCA1 mutations (P=0.04). Moreover, patients with triple-negative breast cancer (TNBC) were more likely to harbor BRCA1 mutations than those with HR+ or HER2+ breast cancer (P=0.006). While there was no significant survival difference observed in BRCA1/2 carriers relative to non-carriers, patients with DNA damage repair (DDR) gene mutations (mostly frequently BRCA, ATM, RAD50) had worse disease-free survival (P=0.02).

Conclusions

The most prevalent germline mutations in a large cohort of Chinese patients with advanced BC were BRCA1/2 mutations, followed by ATM and RAD50 mutations. In total, approximately 16.0% (57/356) of patients carry deleterious mutations in DDR pathway. Patients with breast or ovarian cancer family history were more likely to carry BRCA1/2 mutations, and ones with DDR mutations had worse survival. These findings suggest that DDR mutations are prevalent in Chinese BC patients who may potentially benefit from treatment with Poly (ADP-ribose) polymerase inhibitors.

Supplemental Cancer Screening for Women With Dense Breasts: Guidance for Health Care Professionals

Mammography is the standard for breast cancer screening. The sensitivity of mammography in identifying breast cancer, however, is reduced for women with dense breasts. Thirty-eight states have passed laws requiring that all women be notified of breast tissue density results in their mammogram report. The notification includes a statement that differs by state, encouraging women to discuss supplemental screening options with their health care professionals (HCPs). Several supplemental screening tests are available for women with dense breast tissue, but no established guidelines exist to direct HCPs in their recommendation of preferred supplemental screening test. Tailored screening, which takes into consideration the patient's mammographic breast density and lifetime breast cancer risk, can guide breast cancer screening strategies that are more comprehensive. This review describes the benefits and limitations of the various available supplemental screening tests to guide HCPs and patients in choosing the appropriate breast cancer screening.

Identifying women with increased risk of breast cancer and implementing risk-reducing strategies and supplemental imaging

Breast cancer (BC) is the second most common cancer in women, affecting 1 in 8 women in the United States (12.5%) in their lifetime. However, some women have a higher lifetime risk of BC because of genetic and lifestyle factors, mammographic breast density, and reproductive and hormonal factors. Because BC risk is variable, screening and prevention strategies should be individualized after considering patient-specific risk factors. Thus, health care professionals need to be able to assess risk profiles, identify high-risk women, and individualize screening and prevention strategies through a shared decision-making process. In this article, we review the risk factors for BC, risk-assessment models that identify high-risk patients, and preventive medications and lifestyle modifications that may decrease risk. We also discuss the benefits and limitations of various supplemental screening methods.

An Overview of PARP Inhibitors for the Treatment of Breast Cancer

Loss-of-function mutations in BRCA1 and BRCA2 are detected in at least 5% of unselected patients with breast cancer (BC). These BC susceptibility genes encode proteins critical for DNA homologous recombination repair (HRR). This review provides an update on oral poly(ADP-ribose) polymerase (PARP) inhibitors for the treatment of BC. Olaparib and talazoparib are PARP inhibitors approved as monotherapies for deleterious/suspected deleterious germline BRCA-mutated, HER2-negative BC. Olaparib is approved in the USA for metastatic BC and in Europe for locally advanced/metastatic BC. Talazoparib is approved for locally advanced/metastatic BC in the USA and Europe. In phase 3 trials, olaparib and talazoparib monotherapies demonstrated significant progression-free survival benefits compared with chemotherapy. Common toxicities were effectively managed by supportive treatment and dose interruptions/reductions. Veliparib combined with platinum-based chemotherapy has also shown promise for locally advanced/metastatic BC in a phase 3 trial. Differences in efficacy and safety across PARP inhibitors (olaparib, talazoparib, veliparib, niraparib, rucaparib) may relate to differences in potency of PARP trapping on DNA and cytotoxic specificity. PARP inhibitors are being investigated in early BC, in novel combinations, and in patients without germline BRCA mutations, including those with somatic BRCA mutations and other HRR gene mutations. Ongoing phase 2/3 studies include PARP inhibitors combined with immune checkpoint inhibitors for the treatment of triple-negative BC. Wider access to testing for BRCA and other mutations, and to genetic counseling, are required to identify patients who could benefit from PARP inhibitor therapy. The advent of PARP inhibitors has potential benefits for BC treatment beyond the locally advanced/metastatic setting.

Nonsense Suppression Therapy: New Hypothesis for the Treatment of Inherited Bone Marrow Failure Syndromes

Inherited bone marrow failure syndromes (IBMFS) are a group of cancer-prone genetic diseases characterized by hypocellular bone marrow with impairment in one or more hematopoietic lineages. The pathogenesis of IBMFS involves mutations in several genes which encode for proteins involved in DNA repair, telomere biology and ribosome biogenesis. The classical IBMFS include Shwachman–Diamond syndrome (SDS), Diamond–Blackfan anemia (DBA), Fanconi anemia (FA), dyskeratosis congenita (DC), and severe congenital neutropenia (SCN). IBMFS are associated with high risk of myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), and solid tumors. Unfortunately, no specific pharmacological therapies have been highly effective for IBMFS. Hematopoietic stem cell transplantation provides a cure for aplastic or myeloid neoplastic complications. However, it does not affect the risk of solid tumors. Since approximately 28% of FA, 24% of SCN, 21% of DBA, 20% of SDS, and 17% of DC patients harbor nonsense mutations in the respective IBMFS-related genes, we discuss the use of the nonsense suppression therapy in these diseases. We recently described the beneficial effect of ataluren, a nonsense suppressor drug, in SDS bone marrow hematopoietic cells ex vivo. A similar approach could be therefore designed for treating other IBMFS. In this review we explain in detail the new generation of nonsense suppressor molecules and their mechanistic roles. Furthermore, we will discuss strengths and limitations of these molecules which are emerging from preclinical and clinical studies. Finally we discuss the state-of-the-art of preclinical and clinical therapeutic studies carried out for IBMFS.

BRCA1 c.5470_5477del, a founder mutation in Chinese Han breast cancer patients

The spectrum and frequency of BRCA1/2 pathogenic variants may be ethnicity-specific. Whether high-frequency founder mutations are present in Chinese women remains largely unknown. In the current study, germline pathogenic variants in the BRCA1/2 genes were determined in 9,505 unselected Chinese Han breast cancer (BC) patients by next-generation and/ or Sanger sequencing. Four hundred and seventy-one (5.0%) BC patients carried BRCA1/2 pathogenic variants in this cohort. A total of 25 recurrent pathogenic variants (at least found in four unrelated patients) were identified in this cohort (8 BRCA1 and 17 BRCA2 recurrent pathogenic variants), 161 patients carried one of these recurrent pathogenic variants in this cohort of 9,505 patients. All of these 25 recurrent pathogenic variants were further explored whether they had founder effect through haplotype analysis. The most common pathogenic variant, BRCA1 c.5470_5477del, was found in 30 BC patients from 29 unrelated families. Twenty-seven of these 29 unrelated patients who carried this BRCA1 c.5470_5477del mutation shared an identical haplotype, indicating that BRCA1 c.5470_5477del was a founder mutation in the Chinese Han population. Furthermore, BRCA1 c.5470_5477del mutation carriers had a significantly worse survival than noncarriers (disease-free survival, p = 0.049; overall survival, p = 0.029). Taken together, our data suggested that BRCA1 c.5470_5477del is a founder mutation in the Chinese Han population and BRCA1 c.5470_5477del mutation carriers have a poor survival.

Germline mutations of multiple breast cancer-related genes are differentially associated with triple-negative breast cancers and prognostic factors

Genetic testing for BRCA1/2 mutations has become the standard clinical practice. Recent findings suggest the clinical significance of multigene panel testing of BRCA1/2 and other cancer-related genes. However, the clinical features of patients with breast cancer with germline mutations identified using multigene panels remain unclear. In this study, DNA samples from 583 Chinese women with breast cancer were subjected to target sequencing for 54 cancer-related genes using a pre-capture pooling method followed by next-generation sequencing. We identified 79 pathogenic germline mutations in 21 cancer-related genes. Forty-five patients (7.7%) harbored BRCA1/2 mutations, and 38 patients (6.5%) carried pathogenic mutations in the remaining 19 genes. PALB2 was the most commonly (1.2%) mutated gene other than BRCA1/2. Most of the identified pathogenic mutations were novel, suggesting mutation screening by using multigene panel testing is important particularly for non-European populations. Mutations in BRCA1/2 and the other cancer-related genes were differentially associated with clinical features. BRCA1 mutation carriers were strongly associated with triple-negative breast cancer (TNBC), whereas BRCA2 mutation carriers were not. Tumors in BRCA1-mutation carriers had a high histological grade. Patients with BRCA2-mutated breast cancers were likely to develop E-cadherin-negative tumors with bone metastases. Furthermore, mutations in PALB2 were strongly associated with TNBC. We demonstrated the usefulness of multigene panel testing and observed that a substantial proportion of patients with breast cancer had hereditary risk factors. Identifying differential associations between mutation status and clinical features will advance our understanding regarding the pathologies of this heterogeneous disease.