Patterns and Prevalence of BRCA1 and BRCA2 Germline Mutations Among Patients with Triple-Negative Breast Cancer: Regional Perspectives

DSCC1 restrains 53BP1/RIF1 signaling at DNA double-strand breaks to promote homologous recombination repair

Mammalian DNA double-strand breaks (DSBs) are repaired by homologous recombination (HR) and non-homologous end joining (NHEJ). HR occurs in the S/G2 phase, while NHEJ dominates in G1 phase. 53BP1 promotes NHEJ by recruiting RIF1 to DSBs in G1, but its inhibition during S/G2 remains unclear. Here, we identify DNA replication and sister chromatid cohesion 1 (DSCC1) as a key regulator that antagonizes 53BP1/RIF1 signaling in a cell-cycle-dependent manner. ATR-mediated phosphorylation of DSCC1 at Thr181 leads to its recruitment to DSB sites and promotes HR by facilitating DNA end resection. During S/G2, E2F1-induced DSCC1 expression is phosphorylated by cyclin-dependent kinase 2 (CDK2), enabling DSCC1 to interact with 53BP1 and restrain ataxia telangiectasia mutated (ATM)-mediated 53BP1 phosphorylation, consequently preventing RIF1 recruitment. Pathologically, DSCC1 is elevated in ovarian cancer, conferring poly (ADP-ribose) polymerase (PARP) inhibitor resistance. Thus, DSCC1 plays a crucial role in DSB repair pathway choice toward HR repair during S/G2 phase, providing a potential target to optimize PARP inhibitor therapy in BRCA1/2-proficient cancers.

Germline sequence variation in cancer genes in Rwandan breast and prostate cancer cases

Cancer genetic data from Sub-Saharan African (SSA) are limited. Patients with female breast (fBC), male breast (mBC), and prostate cancer (PC) in Rwanda underwent germline genetic testing and counseling. Demographic and disease-specific information was collected. A multi-cancer gene panel was used to identify germline Pathogenic Variants (PV) and Variants of Uncertain Significance (VUS). 400 patients (201 with BC and 199 with PC) were consented and recruited to the study. Data was available for 342 patients: 180 with BC (175 women and 5 men) and 162 men with PC. PV were observed in 18.3% fBC, 4.3% PC, and 20% mBC. BRCA2 was the most common PV. Among non-PV carriers, 65% had ≥1 VUS: 31.8% in PC and 33.6% in BC (female and male). Our findings highlight the need for germline genetic testing and counseling in cancer management in SSA.

Multi-Gene Panel Testing for Hereditary Cancer Predisposition Among Patients Sixty-Five Years and Above Diagnosed With Breast Cancer

Background

The availability and affordability of germline genetic testing (GGT) has resulted in a broader utilization in daily clinical practice. However, adherence to testing guidelines is low, especially among older patients, where testing is often not offered.

Methods

In this study, consecutive, newly diagnosed patients with breast cancer (BC) aged ≥ 65 years and eligible for GGT, as per the National Comprehensive Cancer Network (NCCN) guidelines (version 1, 2021), were invited to participate, from March 2021 to December 2022. Patients were offered a restricted (two- or 20-gene panel), or an expanded 84-gene panel.

Results

During the study period, 204 patients were enrolled. The mean (standard deviation (SD)) age at BC diagnosis was 70.5 (5.13) years, ranging 65 - 81 years. All patients were Arab and the majority were Jordanian. The majority (n = 188, 92.2%) had early-stage (stages I and II) disease. One hundred three (50.5%) patients were tested with a restricted two-gene (n = 13) or 20-gene (n = 90) panel, while the remaining 101 (49.5%) patients had an expanded 84-gene panel. Family history of close blood relative(s) with BC was the most common indication for testing (n = 110, 53.9%). Among the entire study cohort, 22 (10.8%) had pathogenic/likely pathogenic germline variants (PGVs) and another 97 (47.5%) had ≥ 1 variants of uncertain significance (VUS). PGV rates were significantly higher with the expanded panel (14.9%) compared to restricted testing (6.8%) (P = 0.032). Similarly, VUS rates were significantly higher with the expanded panel (64.4%) compared to the restricted panel (31.1%) (P < 0.001). The most prevalent genes with PGVs were BRCA1/2 (31.3% of all PGV-positive patients), CHEK2 (23.1%) and ATM (19.2%).

Conclusion

GGT should not be overlooked in older BC patients, as this study demonstrates that > 10% of patients have PGVs, largely in potentially actionable genes.

Mass Spectrometry-Based Proteomics for Classification and Treatment Optimisation of Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC) presents a significant medical challenge due to its highly invasive nature, high rate of metastasis, and lack of drug-targetable receptors, which together lead to poor prognosis and limited treatment options. The traditional treatment guidelines for early TNBC are based on a multimodal approach integrating chemotherapy, surgery, and radiation and are associated with low overall survival and high relapse rates. Therefore, the approach to treating early TNBC has shifted towards neoadjuvant treatment (NAC), given to the patient before surgery and which aims to reduce tumour size, reduce the risk of recurrence, and improve the pathological complete response (pCR) rate. However, recent studies have shown that NAC is associated with only 30% of patients achieving pCR. Thus, novel predictive biomarkers are essential if treatment decisions are to be optimised and chemotherapy toxicities minimised. Given the heterogeneity of TNBC, mass spectrometry-based proteomics technologies offer valuable tools for the discovery of targetable biomarkers for prognosis and prediction of toxicity. These biomarkers can serve as critical targets for therapeutic intervention. This review aims to provide a comprehensive overview of TNBC diagnosis and treatment, highlighting the need for a new approach. Specifically, it highlights how mass spectrometry-based can address key unmet clinical needs by identifying novel protein biomarkers to distinguish and early prognostication between TNBC patient groups who are being treated with NAC. By integrating proteomic insights, we anticipate enhanced treatment personalisation, improved clinical outcomes, and ultimately, increased survival rates for TNBC patients.

BRCA1/2 potential founder variants in the Jordanian population: an opportunity for a customized screening panel

A founder variant is a genetic alteration, that is inherited from a common ancestor together with a surrounding chromosomal segment, and is observed at a high frequency in a defined population. This founder effect occurs as a consequence of long-standing inbreeding of isolated populations. For high-risk cancer predisposition genes, such as BRCA1/2, the identification of founder variants in a certain population could help designing customized cost-effective cancer screening panels. This advantage has been best utilized in designing a customized breast cancer BRCA screening panel for the Ashkenazi Jews (AJ) population, composed of the three BRCA founder variants which account for approximately 90% of identified BRCA alterations. Indeed, the high prevalence of pathogenic BRCA1/2 variants among AJ (~ 2%) has additionally contributed to make population-based screening cost-effective in comparison to family-history-based screening. In Jordan there are multiple demographic characteristics supporting the proposal of a founder effect. A high consanguinity rate of ~ 57% in the nineties of the last century and ~ 30% more recently is a prominent factor, in addition to inbreeding which is often practiced by different sub-populations of the country.This review explains the concept of founder effect, then applies it to analyze published Jordanian BRCA variants, and concludes that nine pathogenic (P) and likely pathogenic (LP) BRCA2 variants together with one pathogenic BRCA1 variant are potential founder variants. Together they make up 43% and 55% of all identified BRCA1/2 alterations in the two largest studied cohorts of young patients and high-risk patients respectively. These variants were identified based on being recurrent and either specific to ethnic groups or being novel. In addition, the report highlights the required testing methodologies to validate these findings, and proposes a health economic evaluation model to test cost-effectiveness of a population-based customized BRCA screening panel for the Jordanian population. The aim of this report is to highlight the potential utilization of founder variants in establishing customized cancer predisposition services, in order to encourage more population-based genomic studies in Jordan and similar populations.

Guideline-Based, Multi-Gene Panel Germline Genetic Testing for at-Risk Patients with Breast Cancer

BACKGROUND

Genetic testing for at-risk patients with breast cancer should be routinely offered. Knowledge generated may influence both treatment decisions and cancer prevention strategies among the patients themselves and their relatives. In this study, we report on the prevalence and patterns of germline mutations, using commercially available next-generation sequencing (NGS)-based multi-gene panels (MGP).

PATIENTS AND METHODS

Consecutive at-risk breast cancer patients, as determined by international guidelines, were offered germline genetic testing using a 20-gene NGS-based panel at a reference lab. Samples of peripheral blood were obtained for DNA extraction and genetic variants were classified as benign/likely benign (negative), pathogenic/likely pathogenic (positive) or variants of uncertain significance (VUS).

RESULTS

A total of 1310 patients, median age (range) 43 (19-82) years, were enrolled. Age ≤45 years (n = 800, 61.1%) was the most common indication for testing. Positive family history of breast, ovarian, pancreatic or prostate cancers, and triple-negative disease were among the common indications. Among the whole group, 184 (14.0%) patients had pathogenic/likely pathogenic variants; only 90 (48.9%) were in BRCA1 or BRCA2, while 94 (51.9%) others had pathogenic variants in other genes; mostly in APC, TP53, CHEK2 and PALB2. Mutation rates were significantly higher among patients with positive family history (p = 0.009); especially if they were 50 years or younger at the time of breast cancer diagnosis (p < 0.001). Patients with triple-negative disease had relatively higher rate (17.5%), and mostly in BRCA1/2 genes (71.4%). Variants of uncertain significance (VUS) were reported in 559 (42.7%) patients; majority (90.7%) were in genes other than BRCA1 or BRCA2.

CONCLUSION

Pathogenic mutations in genes other than BRCA1/2 are relatively common and could have been missed if genetic testing was restricted to BRCA1/2. The significantly high rate of VUS associated with multi-gene panel testing can be disturbing.

Breast Cancer-Epidemiology, Classification, Pathogenesis and Treatment (Review of Literature)

Breast cancer is the most-commonly diagnosed malignant tumor in women in the world, as well as the first cause of death from malignant tumors. The incidence of breast cancer is constantly increasing in all regions of the world. For this reason, despite the progress in its detection and treatment, which translates into improved mortality rates, it seems necessary to look for new therapeutic methods, and predictive and prognostic factors. Treatment strategies vary depending on the molecular subtype. Breast cancer treatment is multidisciplinary; it includes approaches to locoregional therapy (surgery and radiation therapy) and systemic therapy. Systemic therapies include hormone therapy for hormone-positive disease, chemotherapy, anti-HER2 therapy for HER2-positive disease, and quite recently, immunotherapy. Triple negative breast cancer is responsible for more than 15-20% of all breast cancers. It is of particular research interest as it presents a therapeutic challenge, mainly due to its low response to treatment and its highly invasive nature. Future therapeutic concepts for breast cancer aim to individualize therapy and de-escalate and escalate treatment based on cancer biology and early response to therapy. The article presents a review of the literature on breast carcinoma-a disease affecting women in the world.