Dynamic Monitoring of Circulating Tumor DNA in Patients With Metastatic Colorectal Cancer

PURPOSE

Plasma circulating tumor DNA (ctDNA) is a valuable resource for tumor characterization and for monitoring of residual disease during treatment; however, it is not yet introduced in metastatic colorectal cancer (mCRC) routine clinical practice. In this retrospective exploratory study, we evaluated the role of ctDNA in patients with mCRC treated with chemotherapy plus bevacizumab.

MATERIALS AND METHODS

Fifty-three patients were characterized for RAS and BRAF status on tumor tissue before the start of treatment. Plasma was collected at baseline, at first clinical evaluation, and at disease progression. ctDNA analysis was performed using Oncomine Colon cfDNA Assay on the Ion S5 XL instrument.

RESULTS

At baseline, from a plasma sample, RAS, BRAF, or PIK3CA mutations were detected in 44 patients. A high correspondence was observed between ctDNA and tumor tissue mutations (KRAS 100%, NRAS 97.9%, BRAF 97.9%, PIK3CA 90%). Low baseline variant allele frequency (VAF) was found to be associated with longer median progression-free survival (PFS) compared with those with high VAF (15.9 v 12.2 months, P = .02). A higher PFS {12.29 months (95% CI, 9.03 to 17.9) v 8.15 months (95% CI, 2.76 to not available [NA]), P = .04} and overall survival (34.1 months [95% CI, 21.68 to NA] v 11.1 months [95% CI, 3.71 to NA], P = .003) were observed in patients with large decline in VAF at first evaluation.

CONCLUSION

ctDNA analysis is useful for molecular characterization and tumor response monitoring in patients with mCRC. Quantitative variations of released ctDNA are associated with clinical outcomes.

Impact of the time interval between primary or interval surgery and adjuvant chemotherapy in ovarian cancer patients

Introduction

Primary debulking surgery (PDS), interval debulking surgery (IDS), and platinum-based chemotherapy are the current standard treatments for advanced ovarian cancer (OC). The time to initiation of adjuvant chemotherapy (TTC) could influence patient outcomes.

Methods

We conducted a multicenter retrospective cohort study of advanced (International Federation of Gynecology and Obstetrics (FIGO) stage III or IV) OC treated between 2014 and 2018 to assess progression-free survival (PFS) and overall survival (OS) in relation to TTC. All patients underwent a germline multigene panel for BRCA1/2 evaluation.

Results

Among the 83 patients who underwent PDS, a TTC ≥ 60 days was associated with a shorter PFS (hazard ratio (HR) 2.02, 95% confidence interval (CI) 1.04-3.93, p = 0.038), although this association lost statistical significance when adjusting for residual disease (HR 1.52, 95% CI 0.75-3.06, p = 0.244, for TTC and HR 2.73, 95% CI 1.50-4.96, p = 0.001, for residual disease). Among 52 IDS patients, we found no evidence of an association between TTC and clinical outcomes. Ascites, type of chemotherapy, or germline BRCA1/2 mutational status did not influence TTC and were not associated with clinical outcomes in PDS or IDS patients.

Discussion

In conclusion, longer TTC seems to negatively affect prognosis in patients undergoing PDS, especially those with residual disease.

Prevalence of a BRCA2 Pathogenic Variant in Hereditary-Breast-and-Ovarian-Cancer-Syndrome Families with Increased Risk of Pancreatic Cancer in a Restricted Italian Area

PVs and LPVs in BRCA1/2 genes are correlated to a high risk of developing breast cancer and/or ovarian cancer (Hereditary Breast and Ovarian Cancer syndrome, HBOC); additionally, in recent years, an increasing number of BRCA 1/2 variants have been identified and associated with pancreatic cancer. Epidemiologic studies have highlighted that inherited factors are involved in 10% to 20% of PCs, mainly through deleterious variants of BRCA2. The frequency of BRCA1/2 germline alterations fluctuates quite a lot among different ethnic groups, and the estimated rate of PVs/LPVs variants in Italian HBOC families is not very accurate, according to different reports. The aim of our study is to describe the prevalence of a BRCA2 PV observed in a selected cohort of HBOC patients and their relatives, whose common origin is the eastern coast of Emilia Romagna, a region of Italy. This study provides insight into the frequency of the variant detected in this area and provides evidence of an increased risk of pancreatic and breast cancer, useful for genetic counseling and surveillance programs.

Molecular Landscape and Association With Crohn Disease of Poorly Cohesive Carcinomas of the Nonampullary Small Bowel

OBJECTIVES

Poorly cohesive carcinomas (PCCs) are neoplasms defined by a predominantly dyshesive growth pattern with single cell or cord-like stromal infiltration. The -distinctive clinicopathologic and prognostic features of small bowel PCCs (SB-PCCs) in comparison with conventional-type small intestinal adenocarcinomas have only recently been characterized. However, as SB-PCCs' genetic profile is still unknown, we aimed to analyze the molecular landscape of SB-PCCs.

METHODS

A next-generation sequencing analysis through Trusight Oncology 500 on a series of 15 nonampullary SB-PCCs was performed.

RESULTS

The most frequently found gene alterations were TP53 (53%) and RHOA (13%) mutations and KRAS amplification (13%), whereas KRAS, BRAF, and PIK3CA mutations were not identified. Most SB-PCCs (80%) were associated with Crohn disease, including both RHOA-mutated SB-PCCs, which featured a non-SRC-type histology, and showed a peculiar appendiceal-type, low-grade goblet cell adenocarcinoma (GCA)-like component. Rarely, SB-PCCs showed high microsatellite instability, mutations in IDH1 and ERBB2 genes, or FGFR2 amplification (one case each), which are established or promising therapeutic targets in such aggressive cancers.

CONCLUSIONS

SB-PCCs may harbor RHOA mutations, which are reminiscent of the diffuse subtype of gastric cancers or appendiceal GCAs, while KRAS and PIK3CA mutations, commonly involved in colorectal and small bowel adenocarcinomas, are not typical of such cancers.

Genotype-first approach to identify associations between CDH1 germline variants and cancer phenotypes: a multicentre study by the European Reference Network on Genetic Tumour Risk Syndromes

BACKGROUND

Truncating pathogenic or likely pathogenic variants of CDH1 cause hereditary diffuse gastric cancer (HDGC), a tumour risk syndrome that predisposes carrier individuals to diffuse gastric and lobular breast cancer. Rare CDH1 missense variants are often classified as variants of unknown significance. We conducted a genotype-phenotype analysis in families carrying rare CDH1 variants, comparing cancer spectrum in carriers of pathogenic or likely pathogenic variants (PV/LPV; analysed jointly) or missense variants of unknown significance, assessing the frequency of families with lobular breast cancer among PV/LPV carrier families, and testing the performance of lobular breast cancer-expanded criteria for CDH1 testing.

METHODS

This genotype-first study used retrospective diagnostic and clinical data from 854 carriers of 398 rare CDH1 variants and 1021 relatives, irrespective of HDGC clinical criteria, from 29 institutions in ten member-countries of the European Reference Network on Tumour Risk Syndromes (ERN GENTURIS). Data were collected from Oct 1, 2018, to Sept 20, 2022. Variants were classified by molecular type and clinical actionability with the American College of Medical Genetics and Association for Molecular Pathology CDH1 guidelines (version 2). Families were categorised by whether they fulfilled the 2015 and 2020 HDGC clinical criteria. Genotype-phenotype associations were analysed by Student's t test, Kruskal-Wallis, χ², and multivariable logistic regression models. Performance of HDGC clinical criteria sets were assessed with an equivalence test and Youden index, and the areas under the receiver operating characteristic curves were compared by Z test.

FINDINGS

From 1971 phenotypes (contributed by 854 probands and 1021 relatives aged 1-93 years), 460 had gastric and breast cancer histology available. CDH1 truncating PV/LPVs occurred in 176 (21%) of 854 families and missense variants of unknown significance in 169 (20%) families. Multivariable logistic regression comparing phenotypes occurring in families carrying PV/LPVs or missense variants of unknown significance showed that lobular breast cancer had the greatest positive association with the presence of PV/LPVs (odds ratio 12·39 [95% CI 2·66-57·74], p=0·0014), followed by diffuse gastric cancer (8·00 [2·18-29·39], p=0·0017) and gastric cancer (7·81 [2·03-29·96], p=0·0027). 136 (77%) of 176 families carrying PV/LPVs fulfilled the 2015 HDGC criteria. Of the remaining 40 (23%) families, who did not fulfil the 2015 criteria, 11 fulfilled the 2020 HDGC criteria, and 18 had lobular breast cancer only or lobular breast cancer and gastric cancer, but did not meet the 2020 criteria. No specific CDH1 variant was found to predispose individuals specifically to lobular breast cancer, although 12 (7%) of 176 PV/LPV carrier families had lobular breast cancer only. Addition of three new lobular breast cancer-centred criteria improved testing sensitivity while retaining high specificity. The probability of finding CDH1 PV/LPVs in patients fulfilling the lobular breast cancer-expanded criteria, compared with the 2020 criteria, increased significantly (AUC 0·92 vs 0·88; Z score 3·54; p=0·0004).

INTERPRETATION

CDH1 PV/LPVs were positively associated with HDGC-related phenotypes (lobular breast cancer, diffuse gastric cancer, and gastric cancer), and no evidence for a positive association with these phenotypes was found for CDH1 missense variants of unknown significance. CDH1 PV/LPVs occurred often in families with lobular breast cancer who did not fulfil the 2020 HDGC criteria, supporting the expansion of lobular breast cancer-centred criteria.

FUNDING

European Reference Network on Genetic Tumour Risk Syndromes, European Regional Development Fund, Fundação para a Ciência e a Tecnologia (Portugal), Cancer Research UK, and European Union's Horizon 2020 research and innovation programme.

Case Report: Male Lobular Breast Cancer in Hereditary Cancer Syndromes

Background

Lobular breast carcinoma (LBC) is considered an exceptionally rare disease in men, including only 1% of all male breast malignancies. The majority of LBCs have negative immunohistochemical staining for E-cadherin (CDH1) expression, and the loss of CDH1 function was traditionally implicated in the tumorigenesis of diffuse gastric cancer as well as LBC. It is well recognized that LBC in women could be involved in both hereditary breast and ovarian cancer (HBOC) and hereditary diffuse gastric cancer (HDGC) syndromes; however, there are no data present in literature about the involvement of male LBC in these inherited conditions.

Methods

BRCA1, BRCA2, and CDH1 genes were performed on DNA from peripheral blood using next-generation sequencing (NGS), Sanger sequencing, and multiplex ligation-dependent probe amplification analyses. BRCA2 and CDH1 somatic gene analyses were performed on breast tumoral DNA using the NGS sequencing approach.

Results and conclusions

Here, we describe two men affected by LBC, the carriers of a pathogenic variant of BRCA2 and CDH1 genes, respectively. Our data, including somatic and germline results, demonstrate a strong relationship between male LBC and HBOC/HDGC syndromes, excluding a sporadic origin of LBC in these two patients. Male LBC could represent a sentinel cancer for inherited syndrome identification, and early identification of cancer susceptibility could improve cancer prevention both for men and women in these families. The history of the LBC patient carrier of the CDH1 variant suggests to include male LBC genetic testing criteria and male breast surveillance in HDGC guidelines.

Poorly Cohesive Carcinoma of the Nonampullary Small Intestine: A Distinct Histologic Subtype With Prognostic Significance

Poorly cohesive carcinomas (PCCs) are neoplasms characterized by a dyshesive cell invasion pattern featuring single-cell or cord-like stromal infiltration. Although they have been extensively studied in the stomach and other digestive system organs, limited data regarding nonampullary small bowel poorly cohesive carcinomas (SB-PCCs) are hitherto available. The aims of our study were to analyze the clinicopathologic and immunophenotypical features of SB-PCCs (PCC pattern accounting for >50% of the neoplasm) and to compare them with small bowel adenocarcinomas (SBAs), not otherwise specified (SBAs-NOS) and with cancers with a histologically distinct PCC component accounting for 10% to 50% of the neoplasm (mixed-poorly-cohesive-glandular-SBAs). Fifteen SB-PCCs were identified and compared with 95 SBAs-NOS and 27 mixed-poorly-cohesive-glandular-SBAs. Most SB-PCCs (67%) were composed of <10% of signet-ring cells, and all but 1 SB-PCCs exhibited loss of membranous expression of E-cadherin. Compared with SBAs-NOS, SB-PCCs showed a significantly younger patient age at diagnosis, and a stronger association with Crohn disease, and both SB-PCCs and mixed-poorly-cohesive-glandular-SBAs featured a higher rate of lymphovascular and perineural invasion and a lower percentage of mismatch repair-deficient cases. Importantly, the cancer-specific survival of SB-PCC (hazard ratio: 3.81; 95% confidence interval: 1.90-7.64; P<0.001) and mixed-poorly-cohesive-glandular-SBA (4.12; 2.20-7.71; P<0.001) patients was significantly worse compared with SBAs-NOS cases. This study provides objective evidence to the World Health Organization (WHO) 2019 introduction of SB-PCC as a distinctive subtype of nonampullary SBA, by virtue of its unique clinical and histologic features, and suggests that both SB-PCCs and mixed-poorly-cohesive-glandular-SBAs should be separated from SBAs-NOS.

Moving beyond PARP Inhibition: Current State and Future Perspectives in Breast Cancer

Breast cancer is the most frequent and lethal tumor in women and finding the best therapeutic strategy for each patient is an important challenge. PARP inhibitors (PARPis) are the first, clinically approved drugs designed to exploit synthetic lethality in tumors harboring BRCA1/2 mutations. Recent evidence indicates that PARPis have the potential to be used both in monotherapy and combination strategies in breast cancer treatment. In this review, we show the mechanism of action of PARPis and discuss the latest clinical applications in different breast cancer treatment settings, including the use as neoadjuvant and adjuvant approaches. Furthermore, as a class, PARPis show many similarities but also certain critical differences which can have essential clinical implications. Finally, we report the current knowledge about the resistance mechanisms to PARPis. A systematic PubMed search, using the entry terms “PARP inhibitors” and “breast cancer”, was performed to identify all published clinical trials (Phase I-II-III) and ongoing trials (ClinicalTrials.gov), that have been reported and discussed in this review.

Abstract 541: Liquid biopsy for molecular characterization and monitoring in patients with metastatic colorectal cancer

The use of liquid biopsy in the clinical management of colorectal cancer (CRC) patients is not yet a routine clinical practice, although it could give important information for tumor baseline characterization and for monitoring during treatment. In this retrospective exploratory study, we examined plasma-circulating tumor DNA (ctDNA) in a series of 27 metastatic CRC patients receiving chemotherapy plus bevacizumab as firstline treatment, both at baseline and at progression. All patients were characterized for RAS and BRAF status on tumor tissue before the start of treatment: 70% of patients were RAS-mutated(16 KRAS, 3 NRAS),15% were BRAF mutated and 15% were RAS/BRAF wild-type. Detection of ctDNA mutations were performed using Oncomine™Colon cfDNA Assay on Ion GeneStudio™ S5 System (Thermofisher). All mutations observed in the tissue were identified also in the baseline ctDNA, excluding one BRAF mutated case that was not detected in the ctDNA. Additional mutations on TP53, APC, PIK3CA, FBXW7 were detected respectively in 11, 12, 3 and 2 cases. TP53 mutations were identified also in 3 RAS/BRAF wild-type cases. Baseline RAS/BRAF variant allele frequency (VAF) lower than 10% was found associated with longer progression free survival (PFS) (log-rank p-value=0.027) (Table 1). At progression, 80% of patients carried the same mutations identified at baseline, and 7 cases carried additional mutations of TP53. Predominantly mutations has a lower VAF at progression with respect to baseline, however RAS/BRAF VAF at progression was found not associated with PFS. In conclusion, we report a concordance-rate &gt;96% between ctDNA and tissue demonstrating the high sensibility of liquid biopsy for detection of mutations in metastatic CRC. Thus, ctDNA could be useful for monitoring of minimal residual disease and tumor heterogeneity during therapeutic treatment. These data, if confirmed in a larger cohort, might support the use of liquid biopsy in the clinical management of CRC patients.

Table 1.Relationships between RAS/BRAF mutation VAF and progression free survival during treatmentTimeConditionN. of casesMedian PFS (range), daysχ2p-valueBaselineVAF&lt;10%11504 (244-843)4,8960,0269VAF&gt;10%11373 (41-719)ProgressionVAF&lt;10%14414 (110-763)0,32390,5693VAF&gt;10%8412 (41-843)

Citation Format: Milena Urbini, Giorgia Marisi, Alessandro Passardi, Chiara Molinari, Matteo Canale, Laura Matteucci, Gianluca Tedaldi, Giovanni Martinelli, Giovanni L. Frassineti, Ulivi Paola. Liquid biopsy for molecular characterization and monitoring in patients with metastatic colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 541.

Early Gastric Cancer: identification of molecular markers able to distinguish submucosa-penetrating lesions with different prognosis

BACKGROUND

Early Gastric Cancer (EGC) reaches 25% of the gastric cancers surgically treated in some areas of Northeastern Italy and is usually characterized by a good prognosis. However, among EGCs classified according to Kodama's criteria, Pen A subgroup is characterized by extensive submucosal invasion, lymph node metastases and worse prognosis, whereas Pen B subgroup by better prognosis. The aim of the study was to characterize the differences between Pen A, Pen B and locally advanced gastric cancer (T3N0) in order to identify biomarkers involved in aggressiveness and clinical outcome.

METHODS

We selected 33 Pen A, 34 Pen B and 20 T3N0 tumors and performed immunohistochemistry of mucins, copy number variation analysis of a gene panel, microsatellite instability (MSI), TP53 mutation and loss of heterozygosity (LOH) analyses.

RESULTS

Pen A subgroup was characterized by MUC6 overexpression (p = 0.021). Otherwise, the Pen B subgroup was significantly associated with the amplification of GATA6 gene (p = 0.002). The higher percentage of MSI tumors was observed in T3N0 group (p = 0.002), but no significant differences between EGC types were found. Finally, TP53 gene analysis showed that 32.8% of Pen tumors have a mutation in exons 5-8 and 50.0% presented LOH. Co-occurrence of TP53 mutation and LOH mainly characterized Pen A tumors (p = 0.022).

CONCLUSIONS

Our analyses revealed that clinico-pathological parameters, microsatellite status and frequency of TP53 mutations do not seem to distinguish Pen subgroups. Conversely, the amplification of GATA6 was associated with Pen B, as well as the overexpression of MUC6 and the TP53^mut/LOH significantly characterized Pen A.

Abstract 5296: Instability of non standard microsatellites in metastatic colorectal cancer patients treated with a bevacizumab based chemotherapy

Bevacizumab (B) is a biological agent frequently included in the treatment of metastatic colon cancer (mCRC), although at present there is no effective biomarker that can predict its efficacy. Few studies report a positive association of microsatellite instability (MSI) with the response to anti-angiogenic therapy, but the role of MSI in relation to B efficacy needs to be better understood. Elevated microsatellite alterations at selected tetranucleotides repeats (EMAST) can be observed at higher rate in mCRC patients compared to MSI. The predictive and prognostic role of EMAST has not been completely investigated so far.

Moreover, it is known that angiogenesis in mCRC goes through the activation of VEGF-A, but VEGF-B can be involved in some compensatory effect during anti-VEGF-A treatments. By exploring the UCSC Genome Browser database, we found that the VEGF-B gene possesses a poly-dinucleotide microsatellite (normally 19xAG) which somatic instability has never been reported.

In this study, we analyzed the status of MSI, five EMAST markers (D20S82, D20S85, D8S321, D9S242, MYCL1) and the VEGF-B microsatellite in relation to prognosis in 145 mCRC patients treated with chemotherapy alone (n=51) or chemotherapy plus B (n=94).

MSI high (MSI-H) was detected in four patients (3%) out of 141 participants. Using a multivariable model and adjusting for patient characteristics, microsatellite status remains significantly associated with progression free survival (PFS) and overall survival (OS). The PFS hazard ratio (HR) for MSI-H patients was 3.18 (95% CI 1.09-9.25; p=0.034) and the OS HR was 6.45 (95% CI 2.08-19.99; p=0.001). Eleven (7.8%) patients out of 140 were positive to at least two EMAST markers. EMAST instability was associated with a general worse prognosis, trend that become significant in the group of patients treated with CT plus B in term of PFS (median survival 5 months vs 11. months, p=0.0006) and OS (median survival 6.1 months vs 29.1 months, p&lt;0.0001). The interaction test showed a significant association of D20S82 (PFS p=0.004) and MYCL1(PFS p=0.029), with worse prognosis when treated with CT plus B, adding a possible predictive value in mCRC patients.

The 24.2% of patients (29 out of 120) showed a VEGF-B-poly-AG instability. Amplification of the poly-AG is associated with worse outcome in PSF (7.0 month of median survival vs 28.0 months for patients with shortened poly-AG; p=0.005) in patients treated with CT alone, suggesting that an extended microsatellite in VEGF-B might have a role in the resistance to chemotherapy.

In conclusion, MSI, EMAST and VEGF-B poly-AG instability are associated with prognosis in mCRC patients treated with CT or CT plus B. MSI and EMAST instability are associated with worse prognosis in CT+B patients, while VEGF-B microsatellite instability is linked to worse prognosis in CT patients.

Further investigations are needed but we can hypothesize that MSI, EMAST and VEGF-B poly-AG instability can have some relevance for the clinical outcome of the disease.

Citation Format: Francesca Pirini, Luigi Pasini, Sara Ravaioli, Gianluca Tedaldi, Emanuela Scarpi, Giorgia Marisi, Chiara Molinari, Daniele Calistri, Alessandro Passardi, Paola Ulivi. Instability of non standard microsatellites in metastatic colorectal cancer patients treated with a bevacizumab based chemotherapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5296.

Male Breast Cancer: Results of the Application of Multigene Panel Testing to an Italian Cohort of Patients

Male breast cancer (MBC) is a rare tumor, accounting for less than 1% of all breast cancers. In MBC, genetic predisposition plays an important role; however, only a few studies have investigated in depth the role of genes other than BRCA1 and BRCA2. We performed a Next-Generation Sequencing (NGS) analysis with a panel of 94 cancer predisposition genes on germline DNA from an Italian case series of 70 patients with MBC. Moreover, we searched for large deletions/duplications of BRCA1/2 genes through the Multiplex Ligation-dependent Probe Amplification (MLPA) technique. Through the combination of NGS and MLPA, we identified three pathogenic variants in the BRCA1 gene and six in the BRCA2 gene. Besides these alterations, we found six additional pathogenic/likely-pathogenic variants in PALB2, CHEK2, ATM, RAD51C, BAP1 and EGFR genes. From our study, BRCA1 and BRCA2 emerge as the main genes associated with MBC risk, but also other genes seem to be associated with the disease. Indeed, some of these genes have already been implicated in female breast cancer predisposition, but others are known to be involved in other types of cancer. Consequently, our results suggest that novel genes could be involved in MBC susceptibility, shedding new light on their role in cancer development.

Genetic Predisposition to Breast and Ovarian Cancers: How Many and Which Genes to Test?

Breast and ovarian cancers are some of the most common tumors in females, and the genetic predisposition is emerging as one of the key risk factors in the development of these two malignancies. BRCA1 and BRCA2 are the best-known genes associated with hereditary breast and ovarian cancer. However, recent advances in molecular techniques, Next-Generation Sequencing in particular, have led to the identification of many new genes involved in the predisposition to breast and/or ovarian cancer, with different penetrance estimates. TP53, PTEN, STK11, and CDH1 have been identified as high penetrance genes for the risk of breast/ovarian cancers. Besides them, PALB2, BRIP1, ATM, CHEK2, BARD1, NBN, NF1, RAD51C, RAD51D and mismatch repair genes have been recognized as moderate and low penetrance genes, along with other genes encoding proteins involved in the same pathways, possibly associated with breast/ovarian cancer risk. In this review, we summarize the past and more recent findings in the field of cancer predisposition genes, with insights into the role of the encoded proteins and the associated genetic disorders. Furthermore, we discuss the possible clinical utility of genetic testing in terms of prevention protocols and therapeutic approaches.

Identification of a novel large EPCAM-MSH2 duplication, concurrently with LOHs in chromosome 20 and X, in a family with Lynch syndrome

BACKGROUND

Lynch syndrome (LS) is associated with germline mutations in one of the mismatch repair genes or EPCAM. The majority of the causative alterations are point mutations. Large genomic rearrangements represent only 5-20%. Hypothetically, the allelic imbalance, like the loss of heterozygosity, may be another high penetrance risk factor.

CASE PRESENTATION

We describe the case of a patient who developed 5 tumors during her lifetime and with a family history characterized by a high frequency of tumors associated with LS. The proband was tested for mutations and copy number alterations with a panel of hereditary cancer genes and by SNP array. She showed a 187 Kb duplication including EPCAM and the first 7 exons of MSH2, plus two loss of heterozygosity (LOHs) in chromosome 20 and one in chromosome X which include many tumor suppressor genes.

CONCLUSION

We found a novel large EPCAM-MSH2 duplication associated with LS and the presence of LOHs in regions containing numerous tumor suppressors, raising the hypothesis that these alterations could contribute to cancer susceptibility. Our results underline the importance to deepen the knowledge of molecular mechanisms in order to determine the role in cancer predisposition of novel genetic alterations.

E-cadherin Downregulation and microRNAs in Sporadic Intestinal-Type Gastric Cancer

CDH1 gene, encoding E-cadherin, is a tumor suppressor gene frequently altered in gastric cancers (GCs) of both diffuse (DGC) and intestinal (IGC) histotypes, albeit through different mechanisms. The study aimed to characterize CDH1 expression in sporadic IGC and to investigate whether microRNAs (miRs) are involved in its transcriptional control. We evaluated CDH1 expression by quantitative real-time PCR (RT-qPCR) in 33 IGC patients and found a significant downregulation in tumor tissues compared to normal counterparts (p-value = 0.025). Moreover, 14 miRs, predicted to be involved in CDH1 regulation in both a direct and indirect manner, were selected and analyzed by RT-qPCR in an independent case series of 17 IGCs and matched normal tissues. miR-101, miR-26b, and miR-200c emerged as significantly downregulated and were confirmed in the case series of 33 patients (p-value < 0.001). Finally, we evaluated EZH2 expression, a target of both miR-101 and miR-26b, which showed significant upregulation in IGCs (p-value = 0.005). A significant inverse correlation was observed between EZH2 overexpression and CDH1, miR-101, and miR-26b levels (p-value < 0.001). Our results reinforce the link between CDH1 and IGC, highlighting the role of miRs in its transcriptional control and improving our understanding of GC subtypes and biomarkers.

Evaluation of CYP17A1 and CYP1B1 polymorphisms in male breast cancer risk

Breast cancer in men is a rare and still poorly characterized disease. Inherited mutations in BRCA1, BRCA2 and PALB2 genes, as well as common polymorphisms, play a role in male breast cancer genetic predisposition. Male breast cancer is considered a hormone-dependent tumor specifically related to hyperestrogenism. Polymorphisms in genes involved in estrogen biosynthesis and metabolism pathways, such as CYP17A1 and CYP1B1, have been associated with breast cancer risk. Here, we aimed to investigate the role of CYP17A1 and CYP1B1 polymorphisms in male breast cancer risk. A series of 597 male breast cancer cases and 1022 male controls, recruited within the Italian Multicenter Study on male breast cancer, was genotyped for CYP17A1 rs743572, CYP1B1 rs1056836 and rs1800440 polymorphisms by allelic discrimination real-time PCR with TaqMan probes. Associations with male breast cancer risk were estimated using logistic regression. No statistically significant associations between male breast cancer risk and the three analyzed polymorphisms emerged. Similar results were obtained also when BRCA1/2 mutational status was considered. No significant differences in the distribution of the genotypes according to estrogen receptor status emerged. In conclusion, our study, based on a large series of male breast cancer cases, is likely to exclude a relevant role of CYP17A1 and CYP1B1 polymorphisms in male breast cancer predisposition. Overall, these results add new data to the increasing evidence that polymorphisms in these genes may not be associated with breast cancer risk.

Genetic Testing and Clinical Management Practices for Variants in Non-BRCA1/2 Breast (and Breast/Ovarian) Cancer Susceptibility Genes: An International Survey by the Evidence-Based Network for the Interpretation of Germline Mutant Alleles (ENIGMA) Clinical Working Group

PURPOSE

To describe a snapshot of international genetic testing practices, specifically regarding the use of multigene panels, for hereditary breast/ovarian cancers. We conducted a survey through the Evidence-Based Network for the Interpretation of Germline Mutant Alleles (ENIGMA) consortium, covering questions about 16 non-BRCA1/2 genes.

METHODS

Data were collected via in-person and paper/electronic surveys. ENIGMA members from around the world were invited to participate. Additional information was collected via country networks in the United Kingdom and in Italy.

RESULTS

Responses from 61 cancer genetics practices across 20 countries showed that 16 genes were tested by > 50% of the centers, but only six (PALB2, TP53, PTEN, CHEK2, ATM, and BRIP1) were tested regularly. US centers tested the genes most often, whereas United Kingdom and Italian centers with no direct ENIGMA affiliation at the time of the survey were the least likely to regularly test them. Most centers tested the 16 genes through multigene panels; some centers tested TP53, PTEN, and other cancer syndrome-associated genes individually. Most centers reported (likely) pathogenic variants to patients and would test family members for such variants. Gene-specific guidelines for breast and ovarian cancer risk management were limited and differed among countries, especially with regard to starting age and type of imaging and risk-reducing surgery recommendations.

CONCLUSION

Currently, a small number of genes beyond BRCA1/2 are routinely analyzed worldwide, and management guidelines are limited and largely based on expert opinion. To attain clinical implementation of multigene panel testing through evidence-based management practices, it is paramount that clinicians (and patients) participate in international initiatives that share panel testing data, interpret sequence variants, and collect prospective data to underpin risk estimates and evaluate the outcome of risk intervention strategies.

Cell-free DNA as a diagnostic marker for cancer: current insights

The increasing knowledge of the molecular pathogenesis of cancer and the rapid development of new molecular techniques are promoting the study of early molecular alterations involved in cancer development in body fluids. Specific genetic and epigenetic alterations could be found in plasma, serum, and urine cell-free DNA (cfDNA) and could potentially be used as diagnostic biomarkers for several types of cancers. This review focuses on the role of cfDNA in diagnosis: a PubMed search was performed by selecting papers according to journal impact factor and robustness of statistical analysis. A comprehensive evaluation of “liquid biopsy”, including cfDNA analysis, will be one of the critical challenges to better understand the early mechanisms of cancer development.

Preclinical evidence of multiple mechanisms underlying trastuzumab resistance in gastric cancer

HER2-positive advanced gastric cancer patients frequently develop resistance to trastuzumab through mechanisms still poorly understood. In breast cancer, other members of the HER-family are known to be involved in trastuzumab-resistance, as is overexpression of the scaffold protein IQGAP1. In the present work, we investigated acquired resistance to trastuzumab in gastric cancer experimental models. Trastuzumab-resistant (HR) subclones derived from 3 HER2-overexpressing gastric cancer cells were generated and characterized for alterations in HER2-signaling mechanisms by next-generation sequencing, immunohistochemical, western blot and qRT-PCR techniques, and molecular modeling analysis. All subclones showed a reduced growth rate with respect to parental cell lines but each had a different resistance mechanism. In NCI N87 HR cells, characterized by a marked increase in HER2-signaling pathways with respect to the parental cell line, trastuzumab sensitivity was restored when IQGAP1 expression was silenced. AKG HR subclone showed higher HER3 protein expression than the parental line. High nuclear HER4 levels were observed in KKP HR cells. In conclusion, our study revealed that high IQGAP1 expression leads to resistance to trastuzumab in gastric cancer. Furthermore, 2 new mutations of the HER2 gene that may be involved in acquired resistance were identified in AKG HR and KKP HR subclones.

First evidence of a large CHEK2 duplication involved in cancer predisposition in an Italian family with hereditary breast cancer

BACKGROUND

CHEK2 is a multi-cancer susceptibility gene whose common germline mutations are known to contribute to the risk of developing breast and prostate cancer.

CASE PRESENTATION

Here, we describe an Italian family with a high number of cases of breast cancer and other types of tumour subjected to the MLPA test to verify the presence of BRCA1, BRCA2 and CHEK2 deletions and duplications. We identified a new 23-kb duplication in the CHEK2 gene extending from intron 5 to 13 that was associated with breast cancer in the family. The presence and localisation of the alteration was confirmed by a second analysis by Next-Generation Sequencing.

CONCLUSIONS

This finding suggests that CHEK2 mutations are heterogeneous and that techniques other than sequencing, such as MLPA, are needed to identify CHEK2 mutations. It also indicates that CHEK2 rare variants, such as duplications, can confer a high susceptibility to cancer development and should thus be studied in depth as most of our knowledge of CHEK2 concerns common mutations.