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AIM: Most patients tested by a 44-gene panel for hereditary cancer (HerediGene), even though they had a strong family history, have a negative result or a finding in a low-risk gene. This creates a question about the risk for these individuals to develop breast cancer. The Polygenic Risk Score is a tool used to identify and calculate the lifetime risk of developing breast cancer and thus we are investigating whether it can be used in our cohort of patients to identify this risk. PATIENTS AND METHODS: Among 111 patients analyzed with a 44-gene hereditary cancer panel, we were able to produce the Polygenic Risk Score for 105 of them. All the patients were diagnosed with breast cancer, and they all had a strong family history. We analyzed the ability of the PRS to identify the risk of the patients in combination with the findings of the 44-gene panel. RESULTS: Overall, 74% of patients with a family history had a negative PRS (with a cut-off of 20%). Among the BRCA positive patients all of them had a positive PRS and among all the high-risk gene positive cases, 70% had a positive PRS. On the other hand, among the low-risk genes and the negative cases 18.5% had a positive PRS. There is a positive correlation between the findings from the NGS panel analysis and the PRS. CONCLUSION: Our analysis shows that PRS is correlated to the findings of the 44-gene NGS panel having the majority of the PRS positive patients carry high risk mutations. In addition to this, in 18.5% of the patients with low-risk findings or negative result from the 44-gene panel, the PRS was positive which can explain the outcome of the patient since breast cancer had developed. This is an indication that the combination of PRS with the findings from the 44-gene panel can identify individuals with a higher risk of developing breast cancer. Citation Format: Nikolaos Tsoulos, Konstantinos Agiannitopoulos, Helen Goga, Theodoros Troupis, Christos Markopoulos. Polygenic Risk Score in a cohort of 105 Breast Cancer patients previously tested with a multi gene panel for hereditary cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-12-07.

Background: Breast cancer is the most frequently diagnosed cancer in women and about 10% of breast cancer cases are hereditary. BRCA1 and BRCA2 are the genes most frequently associated with Hereditary Breast Cancer, although there are numerous other genes, such as PALB2, CHEK2 and ATM, that require to be considered as well. Germline Copy Number Variation (CNV) is one mutation type that is an important contributor to hereditary breast cancer. Nowadays, next-generation sequencing (NGS) technologies has contributed to multi-gene panel analysis used in clinical practice. Methods: In total, 1418 individuals were tested for breast cancer predisposition, using a solution-based capture approach. Targeted NGS was performed with a panel of 36 genes. The capture-based approach allowed for computational analysis of CNVs from NGS data. Results: We investigate the performance of the CNV module of the commercial software suite SeqPilot (JSI Medical Systems) and the non-commercial tool panelcn.MOPS. Both algorithms are specifically developed for CNV analysis of sequencing data reporting 99-100% sensitivity and up to 100% specificity for the prediction of CNVs up to the level of a single gene exon. All CNVs detected with these algorithms were then verified experimentally using the MLPA technique as an orthogonal assay. At least one pathogenic/likely pathogenic variant was identified in 289 samples (20.4%). CNVs accounted for 10.4% (30/289), referring to the deletion of one or more exons of a gene. Interestingly, 50% of deletions were single exon and approximately 36% of CNVs were detected in genes other than BRCA1/2. In specific, of the 30 CNVs detected, 60% occurred in BRCA1, 3.3% in BRCA2, 20% in CHEK2, 6.7% in FANCA, 6.7% in PMS2, and 3.3% in ATM. The majority of CNVs in BRCA1 were deletions of exons 19, 22, and 22-23 whereas deletions of exons 9-10 were the most common deletions in CHEK2. Detailed information of all CNVs detected is provided in Table 1. Conclusions: Our results suggest that CNV analysis should not be restricted to BRCA1/2 due to the significant proportion of CNVs (36%) in additional breast cancer predisposition genes. Furthermore, in silico CNV detection tools provide a cost-effective and feasible methodology for the identification of CNVs from NGS experiments. This outlines the clinical utility of comprehensive genetic testing that includes full sequencing and CNV analysis in hereditary breast cancer facilitating personalized management decisions for patients. Table 1.Pathogenic Copy Number Variations (CNVs) identified in this studyGeneHGVS nomenclatureOther nomenclature# detectedATMNM_000051:c.(-30+1_-29-1)_(331+1_332-1)deldeletion of exons 2-41BRCA1NM_007294:c.(5467+1_5468-1)-(*1_?)deldeletion of exon 237BRCA1NM_007294:c.(5406+1_5407-1)_(*1_?)deldeletion of exons 23-245BRCA1NM_007294:c.(5193+1_5194-1)-(5277+1_5278-1)deldeletion of exon 196BRCA2NM_000059:c.(6841+1_6842-1)_(7007+1_7008-1)deldeletion of exons 12-131CHEK2NM_007194:c.(908+1_909-1)_(1095+1_1096-1)deldeletion of exons 9-104CHEK2NM_007194:c.(792+1_793-1)_(846+1_847-1)deletion of exon 72FANCANM_000135:c.(1626+1_1627-1)_ (2852+1_2853-1)deldeletion of exons 18-291FANCANM_000135:c.(893+1_894-1)_(1359+1_1360-1)deldeletion of exons 11-141PMS2NM_000535: c.(903+1_904-1)_(988+1_989-1)deldeletion of exon 91PMS2NM_000535:c.(705+1_706-1)_(2006+1_2007-1)deldeletion of exons 7-111 Citation Format: Nikolaos Tsoulos, Konstantinos Agiannitopoulos, Georgia Pepe, Eirini Papadopoulou, Georgios N Tsaousis, Despina Apostolopoulou, Angeliki Meintani, Vassileios Venizelos, Christos Markopoulos, Rodoniki Iosifidou, Sofia Karageorgopoulou, Christos Christodoulou, Ioannis Natsiopoulos, Konstantinos Papazisis, Maria Vasilaki-Antonatou, Eleftherios Kabletsas, Amanta Psyrri, Stylianos Giassas, Dimitrios Ziogas, Efthalia Lalla, Anna Koumarianou, Christos Papadimitriou, Vahit Ozmen, Sualp Tansan, Kerim Kaban, Tahsin Ozatlı, Dan Tudor Eniu, Angelica Chiorean, Alexandru Blidaru, George Nasioulas. Different CNVs account for 10.4% of pathogenic variants in 1418 patients referred for hereditary breast cancer testing [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-09-10.

Background: Comprehensive tumor analysis by Next Generation Sequencing (NGS) is imperative for targeted and immunotherapy related biomarkers’ analysis in metastatic breast cancer enabling personalization of cancer treatment in these patients. In parallel with targeted therapies, immunotherapies are also evolving, revolutionizing cancer therapy. Thus, biomarkers such as. Microsatellite Instability (MSI), and Tumor Mutational Burden (TMB) are commonly employed in NGS analysis due to their correlation to Immune Checkpoint inhibitors treatment.Methods: In the present study, tumor molecular profile analysis was performed in 73 metastatic breast cancer patients using a broad NGS assay, which analyzes more than 500 unique cancer related genes and is able to detect relevant single nucleotide variations (SNVs), indels, copy number variations (CNVs) and gene fusions, in addition to TMB and MS) simultaneously. Results: An actionable alteration was detected in 79.45% of the patients. 35.62% of them had at least one alteration with an on label treatment associated and 10.96% received information related to an off-label treatment (Tiers 1A.1 and 2C.1 respectively). Additionally, 31.51% of the tumors harbored an alteration that could be used for clinical trial inclusion (Table 1). The most prevalent altered gene in these patients was the PIK3CA gene, with 27.40% mutation rate. Moreover, in 11 cases (15.07%) the mutation detected was in a gene involved in the Homologous recombination (HR) pathway, with evidence of response to PARP inhibitors. BRCA1/2 genes were as expected the most prominent HR mutated genes (5 out of 11 HR mutations), while the remaining HR mutations involved other HR genes (ATM, BLM, CHEK2, FANCM, RAD50). 24.66% of the tumors had a TMB value >10muts/MB and thus were eligible for ICI treatment. The addition of TMB to targeted biomarkers’ analysis increased the number of patients with an on-label treatment recommendation by 8.22%. Conclusions: Tumor molecular profile analysis using NGS, in real world samples, is a first-tier method for metastatic breast cancer and provides important information for decision making in the treatment of such patients. Importantly, simultaneous analysis for targeted therapy and immunotherapy biomarkers could lead to better tumor characterization and offered actionable information in 9 out of 10 patients tested. However, appropriate interpretation of results from such analysis is essential for implementation in clinical practice and accurate refinement of the treatment strategy.. Table 1.Biomarker's summary in the 73 patients included in the studyPercentage of patients with Tier1 variantsPercentage of patients with 2C.1 variantsPercentage of patients with 2C.2/2D variantsPercentage of patients with Tier 3 variantsPercentage of patients with TMB>10muts/MBMEDIAN TMBPercentage of MSI-High patients35.62% (26/73)10.96% (8/73)12.33% (9/73)0% (0/73)24.66% (18/73)5.050% (0/73) Citation Format: Eirini Papadopoulou, Nikolaos Tsoulos, Vasiliki Metaxa-Mariatou, Aikaterini Tsantikidi, Georgios Kapetsis, Chrysiida Florou-Chatzigiannidou, Sonia Maravelaki, Evgenia Bourkoula, Dimitrios Fotiou, Georgios Tsaousis, Nikolaos Touroutoglou, Dimitrios Trafalis, Ioannis Boukovinas, Ioannis Varthalitis, Zacharenia Saridaki, Charalampos Zoublios, Eleni Galani, George Papatsibas, Christos Papadimitriou, Tania Zlatintsi, Polixenia Iorga, Bülent Orhan, Sualp Tansan, Tahsin Özatlı, George Nasioulas. Comprehensive tumor analysis by NGS in metastatic breast cancer patients [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-13-01.

Background Tumor molecular profile analysis by Next Generation Sequencing technology is currently widely applied in clinical practice and has enabled the detection of predictive biomarkers of response to targeted treatment. In parallel with targeted therapies, immunotherapies are also evolving, revolutionizing cancer therapy, with Programmed Death-ligand 1 (PD-L1), Microsatellite instability (MSI), and Tumor Mutational Burden (TMB) analysis being the biomarkers employed most commonly. Methods In the present study, tumor molecular profile analysis was performed using a 161 gene NGS panel, containing the majority of clinically significant genes for cancer treatment selection. A variety of tumor types have been analyzed, including aggressive and hard to treat cancers such as pancreatic cancer. Besides, the clinical utility of immunotherapy biomarkers (TMB, MSI, PD-L1), was also studied. Results Molecular profile analysis was conducted in 610 cancer patients, while in 393 of them a at least one biomarker for immunotherapy response was requested. An actionable alteration was detected in 77.87% of the patients. 54.75% of them received information related to on-label or off-label treatment (Tiers 1A.1, 1A.2, 2B, and 2C.1) and 21.31% received a variant that could be used for clinical trial inclusion. The addition to immunotherapy biomarker to targeted biomarkers’ analysis in 191 cases increased the number of patients with an on-label treatment recommendation by 22.92%, while an option for on-label or off-label treatment was provided in 71.35% of the cases. Conclusions Tumor molecular profile analysis using NGS is a first-tier method for a variety of tumor types and provides important information for decision making in the treatment of cancer patients. Importantly, simultaneous analysis for targeted therapy and immunotherapy biomarkers could lead to better tumor characterization and offer actionable information in the majority of patients. Furthermore, our data suggest that one in two patients may be eligible for on-label ICI treatment based on biomarker analysis. However, appropriate interpretation of results from such analysis is essential for implementation in clinical practice and accurate refinement of treatment strategy.

AIM: The majority of invasive lobular carcinomas (ILC) of the breast are luminal A tumors of good prognosis, having a low or intermediate OncotypeDX Recurrence Score (RS). They are usually treated with hormonal therapy only and some have doubted the relevance of the RS for patients with ILC. However, in a number of ILC cases a high RS can be found, indicating chemotherapy benefit. The aim of the present analysis was to explore in our database of lobular carcinomas analyzed with OncotypeDX, the percentage of tumors with a RS >25 and test the hypothesis if Progesterone Receptor (PgR) and/or Ki-67 expression could be an indicator to have patients evaluated with OncotypeDX. PATIENTS AND METHODS: Among 2.946 patients analyzed with Oncotype DX, we found 397 patients with pure lobular carcinomas (13.47%). Ki-67 expression was obtained from 315 patients and 13 of them (4%) had a high Ki-67 value of >30%. PgR expression was negative in 56 out of 397 patients (14%). We analyzed the possible relationship of RS values with PgR levels and Ki-67 expression. RESULTS: Overall, 94% of patients with ILC had a Recurrence Score ≤25 and only 6% (24/397) had a RS ≥26. There was a wide distribution of RS among patients with different values of PgR; however, there was a negative trend of Recurrence Score values and PgR expression levels. This trend was more obvious in the 56 patients with negative PgR expression. Although there were high RS values across all levels of Ki-67 expression, there was a trend towards high RS with higher Ki-67 expression; 5 out of 13 patients (38%) with ki-67 >30% had a RS ≥26. CONCLUSION: Our analysis shows that the majority of lobular carcinomas of the breast have a low OncotypeDX RS, suggesting that can be treated only with hormonal therapy. However, negative or low PgR levels and high Ki-67 expression might predict a high RS and thus chemotherapy benefit and those two parameters could be used as indicators for OncotypeDX evaluation of lobular carcinomas of the breast. Citation Format: Christos Markopoulos, Mahi Sariyanni, Asimina Karamargiou, Zoi Antonopoulou, Nikolaos Tsoulos. PgR levels and Ki67 expression of Lobular Carcinomas of the Breast might indicate OncotypeDX testing to evaluate Chemotherapy benefit [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-01-30.

Background/Aim: The use of multi-gene panels for germline testing in breast cancer enables the estimation of cancer risk and guides risk-reducing management options. The aim of this study was to present data that demonstrate the different levels of actionability for multi-gene panels used in genetic testing of breast cancer patients and their family members. Materials and Methods: We performed an analysis in our clinical database to identify breast cancer patients undergoing genetic testing. We reviewed positive results in respect of risk estimation and management, cascade family testing, secondary findings and information for treatment decision-making. Results: A total of 415 positive test reports were identified with 57.1%, 18.1%, 10.8% and 13.5% of individuals having pathogenic/likely pathogenic variants in high, moderate, low and with insufficient evidence for breast cancer risk genes, respectively. Six point seven percent of individuals were double heterozygotes. Conclusion: Germline findings in 92% of individuals are linked to evidence-based treatment information and risk estimates for predisposition to breast and/or other cancer types. The use of germline findings for treatment decision making expands the indication of genetic testing to include individuals that could benefit from targeted treatments.

Background: Tumor molecular profile is of great importance for the detection of biomarkers of response to targeted treatment due to the increased availability, with concomitant reduction of cost, of Next Generation Sequencing technology (NGS). In parallel to targeted therapies’, immunotherapies are also evolving, revolutionizing cancer therapy, with Programmed Death-ligand 1 (PD-L1), Microsatellite Instability (MSI), and Tumor Mutational Burden (TMB) analysis being the biomarkers employed most commonly.Methods: In the present study, a 161 gene NGS panel, containing the majority of clinically significant genes for cancer treatment selection, was used for tumor molecular profile analysis. A variety of tumor types have been analyzed, including aggressive and hard to treat cancers such as pancreatic cancer. Besides, the clinical utility of immunotherapy biomarkers (TMB, MSI, PD-L1), was also studied.Results: Molecular profile analysis was conducted in 610 cancer patients, while in 393 of them a at least one biomarker for immunotherapy response was requested. At least one actionable alteration was detected in 77.70% of the patients. 54.59% of them received information related to on-label or off-label treatment (Tiers 1A.1, 1A.2, 2B, and 2C.1) and 21.31% received a variant that could be used for clinical trial inclusion. The addition to immunotherapy biomarker to targeted biomarkers’ analysis in 191 cases increased the number of patients with an on-label treatment recommendation by 22.40%, while an option for on-label or off-label treatment was provided in 71.35% of the cases. Conclusions: Tumor molecular profile analysis by NGS is a first-tier methodology for a variety of tumor types, which provides critical information for treatment decision making in cancer patients. Importantly, simultaneous analysis for targeted therapy and immunotherapy biomarkers could lead to a better tumor characterization and provide actionable information in the majority of patients. Moreover, our results indicate that one in two patients is eligible for ICI treatment based on the biomarkers’ analysis. However, when these analyses are performed, the challenge is their implementation in clinical practice. Multidisciplinary patient management is critical to the refinement of the strategy incorporating such information.

Gastrointestinal malignancies are among the leading causes of cancer-related deaths worldwide. Like all human malignancies they are characterized by accumulation of mutations which lead to inactivation of tumor suppressor genes or activation of oncogenes. Advances in Molecular Biology techniques have allowed for more accurate analysis of tumors' genetic profiling using new breakthrough technologies such as next generation sequencing (NGS), leading to the development of targeted therapeutical approaches based upon biomarker-selection. During the last 10 years tremendous advances in the development of targeted therapies for patients with advanced cancer have been made, thus various targeted agents, associated with predictive biomarkers, have been developed or are in development for the treatment of patients with gastrointestinal cancer patients. This review summarizes the advances in the field of molecular biomarkers in tumors of the gastrointestinal tract, with focus on the available NGS platforms that enable comprehensive tumor molecular profile analysis.

BackgroundAnalysis of circulating tumor nucleic acids in plasma of Non-Small Cell Lung Cancer (NSCLC) patients is the most widespread and documented form of "liquid biopsy" and provides real-time information on the molecular profile of the tumor without an invasive tissue biopsy.MethodsLiquid biopsy analysis was requested by the referral physician in 121 NSCLC patients at diagnosis and was performed using a sensitive Next Generation Sequencing assay. Additionally, a comparative analysis of NSCLC patients at relapse following EGFR Tyrosine Kinase Inhibitor (TKIs) treatment was performed in 50 patients by both the cobas and NGS platforms.ResultsAt least one mutation was identified in almost 49% of the cases by the NGS approach in NSCLC patients analyzed at diagnosis. In 36 cases with paired tissue available a high concordance of 86.11% was observed for clinically relevant mutations, with a Positive Predictive Value (PPV) of 88.89%. Furthermore, a concordance rate of 82% between cobas and the NGS approach for the EGFR sensitizing mutations (in exons 18, 19, 21) was observed in patients with acquired resistance to EGFR TKIs, while this concordance was 94% for the p.T790M mutation, with NGS being able to detect this mutation in three 3 additional patients.ConclusionsThis study indicates the feasibility of circulating tumor nucleic acids (ctNA) analysis as a tumor biopsy surrogate in clinical practice for NSCLC personalized treatment decision making. The use of new sensitive NGS techniques can reliably detect tumor-derived mutations in liquid biopsy and provide clinically relevant information both before and after targeted treatment in patients with NSCLC. Thus, it could aid physicians in treatment decision making in clinical practice.

e12534 Background: The purpose of this analysis is to evaluate how many patients previously treated according to OncotypeDX Recurrence Score (RS) could have been spared of Chemotherapy if the TAILORx RS data had been taken into account in the clinical treatment decisions. Methods: A series of 182 patients, 34-74 years of age with early breast cancer, treated in our Breast Unit during the last 10 years, for whom treatment decisions were based on OncotypeDX RS. The Recurrence Scores of all these patients were obtained and the actual treatment decisions that were made based on the pre-TAILORx cut-offs of RS 18 and 31 were recorded. These decisions were then re-evaluated based on the after TAILORx cut-off scores, by taking also into consideration the patients’ age. Descriptive statistics were used as well as logistic regression models to estimate the potential change in treatment decisions based on the new Oncotype Dx cut-offs. Results: In the cohort of patients we analyzed that underwent Oncotype Dx testing, 34.1% (62/182) received Chemotherapy, based on the initial pre-TAILORX cut-offs of the RS. When utilizing the new cut-offs (after TAILORx results) in combination with age, we have estimated that, for the patients > 50 years of age, a 12.7% was potentially over-treated and for those ≤50 years old, 9.1% was potentially over-treated since they have received chemotherapy with a RS below 16; additionally, 30.8% of the patients of that age that have RS between 16 and 20 have received chemotherapy even though the average chemotherapy benefit for this group is 1.6% and can go up to 6.7% if they have a high clinical risk as it was defined by the investigators of the TAILORx trial. Finally, 84,6% of patients ≤50 years old with RS between 21-25 received chemotherapy with a 6.5% potential benefit demonstrated in the TAILORx trial. Conclusions: Our analysis suggests that, by using the cut-offs of TAILORx trial, adjuvant chemotherapy could had been omitted in at least a further 11.5% of patients with early breast cancer, reassuring their quality of life without declining their prognosis.

It has been reported that certain patients with non-small-cell lung cancer (NSCLC) that harbor activating somatic mutations within the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) gene may be effectively treated using targeted therapy. The use of EGFR inhibitors in patient therapy has been demonstrated to improve response and survival rates; therefore, it was suggested that clinical screening for EGFR mutations should be performed for all patients. Numerous clinicopathological factors have been associated with EGFR and Kirsten-rat sarcoma oncogene homolog (KRAS) mutational status including gender, smoking history and histology. In addition, it was reported that EGFR mutation frequency in NSCLC patients was ethnicity-dependent, with an incidence rate of ~30% in Asian populations and ~15% in Caucasian populations. However, limited data has been reported on intra-ethnic differences throughout Europe. The present study aimed to investigate the frequency and spectrum of EGFR mutations in 1,472 Greek NSCLC patients. In addition, KRAS mutation analysis was performed in patients with known smoking history in order to determine the correlation of type and mutation frequency with smoking. High-resolution melting curve (HRM) analysis followed by Sanger sequencing was used to identify mutations in exons 18-21 of the EGFR gene and in exon 2 of the KRAS gene. A sensitive next-generation sequencing (NGS) technology was also employed to classify samples with equivocal results. The use of sensitive mutation detection techniques in a large study population of Greek NSCLC patients in routine diagnostic practice revealed an overall EGFR mutation frequency of 15.83%. This mutation frequency was comparable to that previously reported in other European populations. Of note, there was a 99.8% concordance between the HRM method and Sanger sequencing. NGS was found to be the most sensitive method. In addition, female non-smokers demonstrated a high prevalence of EGFR mutations. Furthermore, KRAS mutation analysis in patients with a known smoking history revealed no difference in mutation frequency according to smoking status; however, a different mutation spectrum was observed.

Non‑small cell lung cancer (NSCLC) is the most common type of lung cancer and a tumor with a broad spectrum of targeted therapies already available or in clinical trials. Thus, molecular characterization of the tumor using next generation sequencing (NGS) technology, has become a key tool for facilitating treatment decisions and the clinical management of NSCLC patients. The performance of a custom 23 gene multiplex amplification hot spot panel, based on Ion AmpliSeq™ technology, was evaluated for the analysis of tumor DNA extracted from formalin-fixed and paraffin-embedded (FFPE) tissues. Furthermore, the Ion AmpliSeq™ RNA Fusion Lung Cancer Research Panel was used for fusion RNA transcript analysis. The mutation spectrum of the tumors was determined in a cohort of 502 patients with NSCLC using the aforementioned targeted gene panels. The panel used for tumor DNA analysis in this study exhibited high rates (100%) of sensitivity, specificity and reproducibility at a mutation allelic frequency of 3%. At least one DNA mutation was detected in 374 patients (74.5%) and an RNA fusion was identified in 16 patients, (3.2%). In total, alterations in a cancer-driver gene were identified (including point mutations, gene rearrangements and MET amplifications) in 77.6% of the tumors tested. Among the NSCLC patients, 23% presented a mutation in a gene associated with approved or emerging targeted therapy. More specifically, 13.5% (68/502) presented a mutation in a gene with approved targeted therapy (EGFR, ALK, ROS1) and 9.4% (47/502) had an alteration in a gene related to emerging targeted therapies (ERBB2, BRAF, MET and RET). Furthermore, 51.6% of the patients had a mutation in a gene that could be related to an off label therapy or indicative for access to a clinical trial. Thus, the targeted NGS panel used in this study is a reliable approach for tumor molecular profiling and can be applied in personalized treatment decision making for NSCLC patients.

Background The application of the Next Generation Sequencing (NGS) technology has facilitated multigene panel testing for hereditary breast cancer (BC) in clinical practice. We performed a retrospective analysis of individuals referred for testing in our lab aiming to investigate the contribution of included genes and evaluate current genetic testing guidelines in BC. Methods In total, 1141 BC patients and 184 unaffected individuals with family history (FH) of BC were referred from physicians for testing using a multigene panel. Genomic DNA was enriched for targeted regions of 33 genes and sequencing was carried out using the Illumina NGS technology. The presence of large genomic rearrangements (LGRs) was investigated computationally and by Multiplex Ligation-dependent Probe Amplification (MLPA). Results A pathogenic variant (PV) was identified in 22% (291/1325) of analyzed individuals and in specific in 23.2% of BC patients and 14.1% of unaffected individuals (P = 0.006). Among individuals with PVs, 49.1% were located in the BRCA1/2 genes whereas 8.6%, 22.7% and 19.6% occurred in other high, moderate and low-risk genes respectively. Notably, 21 of the 291 positive individuals (7.2%) carried clinically significant variants in two different genes and 6.5% had a LGR. A retrospective analysis of positive individuals showed that 88.3% of BC patients met the NCCN criteria for further genetic risk evaluation compared to 80.8% of unaffected individuals with FH of BC (P = 0.269). In BRCA-positive cases, NCCN criteria were met in 92.3% of the referrals compared to 81.8% in individuals positive for other genes (P = 0.008). Conclusions Extended multigene panel testing in hereditary BC facilitates the detection of nearly twice as many individuals that could benefit from personalized management. In our cohort, the currently used selection criteria for HBOC failed to identify only 12.7% of individuals positive for pathogenic variants, suggesting strong selection strategies from physicians. However, our results indicate that selection criteria perform better for the identification of BRCA-positive BC patients and should be revised to facilitate towards the inclusion of BC patients with PVs in other genes. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.

BACKGOUND: Hereditary cancer predisposition syndromes are believed to be responsible for approximately 5-10% of all diagnosed cancer cases. In the past, single genes analysis of certain high risk genes was used for the determination of the genetic cause of cancer heritability in certain families. The selection of genes was mainly based on the family history of the individuals analyzed and included only highly associated genes (e.g. the BRCA1 and BRCA2 genes for families with breast cancer history. Nowadays though, the application of Next Generation Sequencing (NGS) technology has facilitated multigene panel analysis and is widely used in clinical practice, for the identification of individuals with cancer predisposition gene mutations. AIM: The aim of this study was to investigate the extent and nature of mutations in 36 genes implicated in hereditary cancer predisposition in individuals referred for testing in our lab. MATERIALS & METHODS: In total, 1197 individuals were referred for testing in our lab in the past four years from Greece, Romania and Turkey. The analysis of genes involved in hereditary cancer predisposition was performed using two NGS approaches. The first 451 individuals were analyzed using an amplicon based sequencing method (26 gene panel), while the following 746 individuals were analyzed using a capture based method (33 gene panel). Genomic DNA was enriched for targeted regions of 36 genes involved in hereditary predisposition to cancer included in both versions of the panel (APC, BMPR1A, BRCA1, BRCA2, CDH1, CDK4, CDKN2A, EPCAM, MEN1, MLH1, MSH2, MSH6, MUTYH, PALB2, PMS2, PTEN, RET, SMAD4, STK11, TP53, VHL, ATM, BRIP1, CHEK2, NBN, RAD51C, RAD51D, BARD1, BLM, CHEK1, ABRAXAS1 (FAM175A), MRE11 (MRE11A), NF1, RAD50, RAD51B, XRCC2). Sequencing was carried out using the Illumina NGS technology. Reads were aligned to the reference sequence (GRCh37), and sequence changes were identified and interpreted in the context of a single clinically relevant transcript. The presence of large genomic rearrangements was investigated by computational analysis of NGS results and the use of MLPA for 13 genes. All clinically significant observations were confirmed by orthogonal technologies. RESULTS: In total, a pathogenic mutation was identified in 259 of the 1197 individuals (21.6%) analyzed while a VUS was identified in 35.7% of the cases. Clinically significant mutations were identified in 29 of the genes analyzed. Concerning the mutation distribution among individuals with positive findings, 44.7% of them were located in BRCA1/2 genes whereas 20.9%, 19.9%, and 14.5% in high, moderate and low risk genes respectively. In addition to BRCA1 and BRCA2 genes other highly mutated genes were CHEK2 (10.6%), PALB2 (7.1%), MUTYH (7.1%) and ATM (4.3%). Of note is that 25 of the 259 positive individuals (9.7%) carried clinically significant mutations in two different genes and 5.8% had a large genomic rearrangement (LGR). CONCLUSIONS: Our results support the clinical significance of analysis of a panel of genes involved in hereditary cancer predisposition. In our cohort, analysis of this panel allowed for the identification of 8.3% additional pathogenic variants in moderate/low risk genes, enabling personalized management of these individuals. Citation Format: Tsoulos N, Tsaousis GN, Papadopoulou E, Agiannitopoulos K, Pepe G, Kambouri S, Apessos A, Diamantopoulos N, Floros T, Iosifidou R, Katopodi O, Koumarianou A, Markopoulos C, Papazisis K, Venizelos V, Xanthakis I, Xepapadakis G, Banu E, Eniu DT, Negru S, Stanculeanu DL, Ungureanu A, Ozmen V, Tansan S, Tekinel M, Yalcin S, Nasioulas G. Analysis of hereditary cancer syndromes by using a panel of genes: Novel and multiple pathogenic mutations [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-03-07.

INTRODUCTION Hereditary breast cancer is estimated to account for approximately 10% of all breast cancer cases. In addition, an estimated 15-20% of those affected by breast cancer have a positive family history. Despite the fact that BRCA1 and BRCA2 are the two most significant genes in hereditary breast cancer predisposition, twenty years of analysis has highlighted the fact, that mutations in these two highly penetrant genes, are only present in approximately 20% of high risk families. Other genes, mutations in which are associated with high risk of breast cancer, were identified because of the strong association with familial cancer syndromes, in which breast cancer is one of the defining components. Technological advances in molecular biology and especially DNA sequencing, commonly designated as “Next Generation Sequencing – NGS” have aided in the concentrated efforts to identify new genes responsible for the missing heritability, allowing the application of this knowledge in the diagnostic setting. AIM The aim of this study was to investigate the extent and nature of mutations in 26 genes implicated in hereditary cancer predisposition in families of Romanian descent. MATERIALS & METHODS In total, 297 Romanian families have been analyzed by our group in the past three years. Genomic DNA was enriched for targeted regions of 26 genes involved in hereditary predisposition to cancer (ATM, BARD1, BLM, BRCA1, BRCA2, BRIP1, CDH1, CHEK2, EPCAM (only intron 8, exon 9 and 3'UTR), FAM175A, MEN1, MLH1, MRE11A, MSH2, MSH6, MUTYH, NBN, PALB2, PMS2, PTEN, RAD50, RAD51C, RAD51D, STK11, TP53, XRCC2). Sequencing was carried out using the Illumina NGS technology. Reads were aligned to the reference sequence (GRCh38), and sequence changes were identified and interpreted in the context of a single clinically relevant transcript. The presence of large genomic rearrangements was investigated by use of MLPA. All clinically significant observations were confirmed by orthogonal technologies. RESULTS In total, a pathogenic mutation was identified in 79 of the 297 families (26.6%) analyzed. Clinically significant mutations were identified in 17 of the genes included in the panel. The most commonly mutated genes in the Romanian population were BRCA1 and BRCA2, accounting for 50% of the mutations identified, followed by PALB2 (12%), CHEK2 (9.4%) and ATM, NBN and RAD50 which accounted for 3.5% of the mutations each. Of note is that 7 of the 79 affected families (8.8%) carried clinically significant mutations in two different genes. CONCLUSIONS Our results support the clinical significance of analysis of a panel of genes involved in hereditary cancer predisposition. In this series of patients, analysis of this panel allowed for the identification of 14% additional pathogenic variants. This is especially true in those cases where more than one pathogenic variant was identified. Citation Format: Tsoulos N, Apessos A, Agiannitopoulos K, Pepe G, Tsaousis G, Kambouri S, Eniu DT, Ungureanu A, Banu E, Ciule L, Blidaru A, Chiorean A, Stanculeanu DL, Mateescu D, Nasioulas G. Analysis of hereditary cancer syndromes by use of a panel of genes: More answers than questions [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-03-03.

e23193 Background: Non-small cell lung cancer (NSCLC) is the most common type of lung cancer and a tumor with broad spectrum of targeted therapies already available or in clinical trials. Thus, molecular characterization of the tumor using the Next Generation Sequencing (NGS) technology, has become a key tool for NSCLC patients’ treatment decision and clinical management. Methods: The performance of a custom 23 gene multiplex amplification hot spot panel, based on Ion AmpliSeq Technology, was evaluated for the analysis of tumor DNA extracted from FFPE (Formalin Fixed Parraffin Embedded) tissue. Furthermore the Ion AmpliSeq™ RNA Fusion Lung Cancer Research Panel was used for fusion RNA transcript analysis. Tumors’ mutation spectrum was determined in a cohort of 502 patients with NSCLC using the aforementioned targeted gene panels. Results: The panel used for tumor DNA analysis in this study exhibit high rates (100%) of sensitivity, specificity and reproducibility at a mutation frequency of 3%. At least one DNA mutation was detected in 374 patients (74.5%) and an RNA fusion was identified in 16 patients, (3.2%). In total, alterations in a cancer driver gene were identified (including point mutations, gene rearrangements and MET amplifications) in 77.6% of the tumors tested. Among the NSCLC patients, 13.5% (68/502) presented a mutation in a gene with approved targeted therapy (EGFR, ALK ROS1) and 9.4% had an alteration in a gene related to emerging targeted therapies according the NCCN guidelines. These alterations include ERBB2, BRAF and MET mutations, MET amplification and RET rearrangements. The remaining 51.6% of the patients had a mutation in a gene that could be related to an off label therapy or give them access to a clinical trial. Conclusions: Thus the NGS panel validated is a reliable approach of clinical applicability for tumor molecular profile detection in NSCLC patients.

It has been reported that certain patients with non-small-cell lung cancer (NSCLC) that harbor activating somatic mutations within the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) gene may be effectively treated using targeted therapy. The use of EGFR inhibitors in patient therapy has been demonstrated to improve response and survival rates; therefore, it was suggested that clinical screening for EGFR mutations should be performed for all patients. Numerous clinicopathological factors have been associated with EGFR and Kirsten-rat sarcoma oncogene homolog (KRAS) mutational status including gender, smoking history and histology. In addition, it was reported that EGFR mutation frequency in NSCLC patients was ethnicity-dependent, with an incidence rate of ~30% in Asian populations and ~15% in Caucasian populations. However, limited data has been reported on intra-ethnic differences throughout Europe. The present study aimed to investigate the frequency and spectrum of EGFR mutations in 1,472 Greek NSCLC patients. In addition, KRAS mutation analysis was performed in patients with known smoking history in order to determine the correlation of type and mutation frequency with smoking. High-resolution melting curve (HRM) analysis followed by Sanger sequencing was used to identify mutations in exons 18–21 of the EGFR gene and in exon 2 of the KRAS gene. A sensitive next-generation sequencing (NGS) technology was also employed to classify samples with equivocal results. The use of sensitive mutation detection techniques in a large study population of Greek NSCLC patients in routine diagnostic practice revealed an overall EGFR mutation frequency of 15.83%. This mutation frequency was comparable to that previously reported in other European populations. Of note, there was a 99.8% concordance between the HRM method and Sanger sequencing. NGS was found to be the most sensitive method. In addition, female non-smokers demonstrated a high prevalence of EGFR mutations. Furthermore, KRAS mutation analysis in patients with a known smoking history revealed no difference in mutation frequency according to smoking status; however, a different mutation spectrum was observed.

e22178 Background: NSCLC patients harboring activating somatic mutations within the tyrosine kinase (TK) domain of the epidermal growth factor receptor (EGFR) significantly benefit from EGFR target...

e12536 Background: Approximately 5-10% of breast cancer cases are hereditary. Germline mutations in the BRCA1 and BRCA2genes are responsible for 80% of inherited breast cancer cases. Carriers of su...