Prevalence Of Pathogenic Germline Variants Research Articles

Germline Pathogenic Variants Identified in Patients With Genitourinary Malignancies Undergoing Universal Testing: A Multisite Single-Institution Prospective Study.

This study aimed to investigate the prevalence of pathogenic germline variants (PGVs) in hereditary cancer genes utilizing a universal testing approach and to determine the rate of PGVs that would have been missed based on National Comprehensive Cancer Network (NCCN) guidelines in genitourinary (GU) malignancies. A multisite, single-institution prospective germline genetic test (GGT) was universally offered to patients with new or active diagnoses of GU malignancies (prostate, bladder, and renal) from April 2018 to March 2020 at Mayo Clinic sites. Participants were offered GGT using a next-generation sequencing panel of > 80 genes. Demographic, tumor characteristics, and genetic results were evaluated. NCCN GU cancer guidelines were used to identify whether patients had incremental findings, defined as PGV-positive patients who would not have received testing based on NCCN guidelines. Of 3095 individuals enrolled in the study, 601 patients had GU cancer (prostate = 358, bladder = 106, and renal = 137). The mean enrollment age was 67 years (SD 9.1), 89% were male, and 86% of patients were non-Hispanic White. PGVs were identified in 82 (14%) of all GU patients. PGV prevalence breakdown by cancer type was: 14% prostate, 14% bladder, and 13% renal cancer. Nearly one-third of identified PGVs were high penetrance, and the majority of these (67%) were clinically actionable. Incremental PGVs were identified in 28 (57%) prostate, 15 (100%) bladder, and 14 (78%) renal cancer patients. Of the 82 patients with PGV findings, 29 (35%) had at least 1 relative undergo cascade testing for the familial variant(s) identified. More than 1 in 8 patients with GU malignancies were found to carry a PGV, with 67% of patients with high-penetrance PGVs undergoing clinically actionable changes. The majority of these PGVs would not have been identified based on current testing criteria. These findings support universal GGT for GU malignancies and underscore its potential to enhance risk assessment and guide precision interventions in urologic oncology.

Germline Genetic Mutations in Adult Patients with Sarcoma: Insight into the Middle East Genetic Landscape.

Data on germline mutations in soft tissue and bone sarcomas are scarce. We sought to identify the prevalence of germline mutations in adult sarcoma patients treated at a tertiary cancer center. Newly diagnosed patients were offered germline genetic testing via an 84-gene panel. The prevalence of pathogenic germline variants (PGVs) and their association with disease-, and patient- related factors are reported. A total of 87 patients were enrolled, the median age was 48 (19-78) years, and 47 (54%) were females. Gastrointestinal stromal tumors (n = 12, 13.8%), liposarcoma (n = 10, 11.5%), and Ewing sarcoma (n = 10, 11.5%) were the main subtypes. A total of 20 PGVs were detected in 18 (20.7%) patients. Variants of uncertain significance, in the absence of PGVs, were detected in 40 (45.9%) patients. Young age (p = 0.031), presence of a second primary cancer (p = 0.019), and female gender (p = 0.042) were correlated with the presence of PGVs. All identified PGVs have potential clinical actionability and cascade testing, and eight (44.44%) suggested eligibility for a targeted therapy. Almost one in five adult patients with soft tissue and bone sarcomas harbor pathogenic or likely pathogenic variants. Many of these variants are potentially actionable, and almost all have implications on cancer screening and family counselling. In this cohort from the Middle East, younger age, presence of a second primary tumor, and female gender were significantly associated with higher PGVs rates. Larger studies able to correlate treatment outcomes with genetic variants are highly needed.

Characterization of Incidental Pathogenic Germline Findings Detected via ctDNA among Patients with Non-Small Cell Lung Cancer in a Predominantly Hispanic/Latinx Population.

Pathogenic germline variants (PGVs) may be under-detected as causative etiologies in patients with non-small cell lung cancer (NSCLC). The prevalence of PGVs has been reported between 1 and 15% of patients, depending on the patient population. The rate within Hispanic/Latinx populations remains unknown. We retrospectively analyzed the genomic results (Guardant360, Redwood City, CA, USA) of 878 patients with advanced or metastatic NSCLC at five centers in South Florida, USA, from 2019 to 2022 to analyze the rate of incidental PGVs (iPGVs) identified via circulating cell-free tumor DNA (ctDNA). We then stratified the results by tumor histology, age, gender, race, ethnicity, genetic pathway, and co-mutations. Twenty-one iPGVs were identified (21/878 = 2.4%). Among the 21 iPGVs identified, 14 patients were female (66.7%) and 7 were male (33.3%), with a median age of 67 years and tobacco history of 2.5 pack-years. In total, 52.4% of patients identified as Hispanic/Latinx (n = 11) of any race; 19.0% as Ashkenazi Jewish (n = 4), 9.5% as non-Hispanic/Latinx black (n = 2), and 19.0% as non-Hispanic/Latinx white (n = 4). iPGVs in the homologous recombination repair pathway were solely expressed in this cohort (10 ATM, 8 BRCA2, and 3 BRCA1). In total, 76% (16/21) of patients with iPGVs co-expressed somatic alterations, with 56% (9/16) demonstrating alterations in targetable genes. Overall, our real-world findings offer a point prevalence of iPGVs in patients with NSCLC of diverse populations, such as patients who report Hispanic/Latinx ethnicity.

Germline pathogenic variants in patients with high-grade gastroenteropancreatic neuroendocrine neoplasms.

High-grade gastroenteropancreatic (HG-GEP) neuroendocrine neoplasms (NENs) are highly aggressive cancers. The molecular etiology of these tumors remains unclear, and the prevalence of pathogenic germline variants in patients with HG-GEP NENs is unknown. We assessed sequencing data of 360 cancer genes in normal tissue from 240 patients with HG-GEP NENs; 198 patients with neuroendocrine carcinomas (NECs) and 42 with grade 3 neuroendocrine tumors (NET G3). Applying strict criteria, we identified pathogenic germline variants and compared the frequency with previously reported data from 33 different cancer types. We found a recurrent MYOC variant in three patients and a recurrent MUTYH variant in two patients, indicating that these genes may be important underlying risk factors for HG-GEP NENs when mutated. Further, germline variants were found in canonical tumor-suppressor genes, such as TP53, RB1, BRIP1 and BAP1. Overall, we found that 4.5% of patients with NEC and 9.5% of patients with NET G3 carry germline pathogenic or highly likely pathogenic variants. Applying identical criteria for variant classification in silico to mined data from 33 other cancer types, the median percentage of patients carrying pathogenic or highly likely pathogenic variants was 3.4% (range: 0-17%). The patients with NEC and pathogenic germline variants had a median overall survival of 9 months, similar to what is generally expected for metastatic GEP NECs. A patient with NET G3 and pathogenic MUTYH variant had much shorter overall survival than expected. The fraction of HG-GEP NENs with germline pathogenic variants is relatively high, but still <10%, meaning that that germline mutations cannot be the major underlying cause of HG-GEP NENs.

Prevalence of pathogenic germline variants in adult-type diffuse glioma.

No consensus germline testing guidelines currently exist for glioma patients, so the prevalence of germline pathogenic variants remains unknown. This study aims to determine the prevalence and type of pathogenic germline variants in adult glioma. A retrospective review at a single institution with paired tumor/normal sequencing from August 2018-April 2022 was performed and corresponding clinical data were collected. We identified 152 glioma patients of which 15 (9.8%) had pathogenic germline variants. Pathogenic germline variants were seen in 11/84 (13.1%) of Glioblastoma, IDH wild type; 3/42 (7.1%) of Astrocytoma, IDH mutant; and 1/26 (3.8%) of Oligodendroglioma, IDH mutant, and 1p/19q co-deleted patients. Pathogenic variants in BRCA2, MUTYH, and CHEK2 were most common (3/15, 20% each). BRCA1 variants occurred in 2/15 (13%) patients, with variants in NF1, ATM, MSH2, and MSH3 occurring in one patient (7%) each. Prior cancer diagnosis was found in 5/15 patients (33%). Second-hit somatic variants were seen in 3/15 patients (20%) in NF1, MUTYH, and MSH2. Referral to genetics was performed in 6/15 (40%) patients with pathogenic germline variants. 14/15 (93%) of patients discovered their pathogenic variant as a result of their paired glioma sequencing. These findings suggest a possible overlooked opportunity for determination of hereditary cancer syndromes with impact on surveillance as well as potential broader treatment options. Further studies that can determine the role of variants in gliomagenesis and confirm the occurrence and types of pathogenic germline variants in patients with IDH wild type compared to IDH mutant tumors are necessary.

Prospective prevalence estimation of BRCA1, BRCA2, and other germline mutations associated with hereditary pancreatic cancer (HPC) using a comprehensive gene panel in an unselected cohort of Mexican patients with pancreatic ductal adenocarcinoma (PDAC).

10609 Background: Prevalence of pathogenic or likely pathogenic germline variants (PGVs) in patients with PDAC varies across populations. There is limited information on the prevalence of PGVs among Mexican patients with PDAC. We prospectively tested an unselected cohort of newly diagnosed PDAC patients using a comprehensive gene panel in order to estimate the prevalence of BRCA1/2, and other germline mutations associated with HPC. Methods: The protocol was approved by the ethics committee at each institution: INCMNSZ, INCAN, and CM ABC Observatorio. Key inclusion criteria: age &gt; 18 years and PDAC diagnosed within 6 months of inclusion. Patients were enrolled consecutively, regardless of age, personal or family history of cancer, known hereditary cancer syndrome, or stage of the disease. Written informed consent was obtained before any procedure. Clinical variables including family history of cancer were collected. We used the 84-gene Invitae Multi-Cancer Panel. Genetic testing had no cost for patients. Patient characteristics and family history were summarized using descriptive statistics (IBM SPSS Statistics Version 25). The trial was registered on Clinical Trials (NCT05305001). Results: From August 2020 to June 2022, 119 patients with newly diagnosed PDAC were identified. Of these, 107 patients were included: 58% women, median age was 63 y/o, clinical stages at diagnosis were: I (24%), II (22%), III (6%), and IV (48%). All patients had Hispanic ancestry except one (Ashkenazi Jewish). Only 7.5% (n = 8) had a personal history of other cancer, mainly breast cancer (N = 3); 62% had a family history of any cancer, while 47.6% had a first-degree relative (FDR) with any cancer. 11% (n = 12) had family history of pancreatic cancer (PC), and 9% (n = 10) had an FDR with PC. Five patients met clinical criteria for hereditary cancer syndrome: familial pancreatic cancer (4) and Lynch syndrome (1). PGVs were identified in 17.8% (n = 19) of patients. The prevalence of PGVs in genes associated with autosomal dominant risk of PC was 11.2%: CDKN2A(5.6%), ATM (3.7%), BRCA2 (0.93%), and MSH6 (0.93%). Two patients had a PGV associated with autosomal dominant predisposition to other cancers ( CHECK2 and NF1). Six patients (5.6%) had PGVs associated with autosomal recessive predisposition to rare syndromes with increased cancer risk other than PDAC (MUTYH, RECQL4, FH and WRN). Variants of uncertain significance were present in 42% of patients. Conclusions: In Mexican patients with PDAC, the prevalence of PGVs on BRCA1/2 is &lt; 1%. The prevalence of PGVs in other susceptibility genes is 11%. Our results support the role of universal germline testing in Mexican patients with PDAC using a comprehensive gene panel. Selective testing for BRCA1/2 is discouraged.

Prevalence of pathogenic germline variants in a cohort of patients with early onset non-small cell lung cancer (EOLUNG).

10630 Background: Patients with early onset lung cancer might be more likely to carry pathogenic (or likely-pathogenic) germline variants (PGV) in genes associated with cancer predisposition. However, germline testing is not recommended in this population. We designed this study to determine the prevalence of PGVs in patients with early onset lung cancer. Methods: This prospective, multicenter cohort study assessed PGV in patients younger than 51 years diagnosed with non-small cell lung cancer (NSCLC) in 3 sites at the Catalan Institute of Oncology between June 2018 to May 2022. Genomic DNA was sequenced using a custom-designed NGS panel covering 164 cancer-predisposing genes and results were discussed in a multidisciplinary tumor board. Results: 138 patients were included. Median age was 45.5 (28-50) years; 49% were females; 79% were ever-smokers with a median packs-year of 24 and median age of tobacco initiation of 16 years old. Most patients had non-squamous histology (88%) and had stage IV (62%) at diagnosis. Somatic oncogenic drivers were found in 74 patients (54%): EGFR 27 (20%); ALK 22 (16%); KRAS 20 (14%); RET 3 (2%); ROS1 1 (1%); BRAF V600E 1 (1%). Only 4% had past personal history of cancer and 50% had family history of cancer in a first-degree relative, being lung and breast cancer the most common tumors. Overall, 20 patients (14%) carried PGVs involving 12 genes associated with cancer predisposition: PARK2 (n=4); SBDS (n=3); NBN (n=2); ATM (n=2); TSC1 (n=2) and BLM, FANCA, MCPH1, PMS2, POLH, SDHA, RECQL4 (n=1, each). Four patients (3%) fulfilled criteria to be referred to genetic counseling clinic. There were no significant differences in clinical and molecular characteristics among patients with PGVs compared to their counterparts (Table). Conclusions: In this prospective cohort, 14% of patients with early onset NSCLC harbored germline PGVs. As clinicopathological and genomic features were not associated with PGVs, germline testing might be considered in addition to comprehensive genomic characterization of tumor tissue in young patients with NSCLC. However, only a minority of PGVs were deemed clinically actionable.[Table: see text]

Frequency of pathogenic germline variants in cancer susceptibility genes in 841 renal cell carcinoma cases.

e16551 Background: Hereditary Renal cell carcinoma (RCC) syndrome accounts for approximately 5-10% of all kidney cancers. However, the genetic architecture of susceptibility to RCC is not well defined. In this study, we investigated the prevalence and spectrum of pathogenic/likely pathogenic germline variants of cancer susceptibility genes in unselected RCC patients in the real-world Chinese population. Methods: We retrospectively profiled the germline mutations of 841 unselected RCC patients using a next-generation sequencing panel consisting of 808 cancer-related genes. Interpretation of sequence variations was classified according to the American College of Medical Genetics and Genomics guidelines. Genomic alterations include single nucleotide variations (SNV), short insertions/deletions (INDEL) and copy number variations (CNV). Results: Within 841 unselected RCC patients included in this study, 132 germline pathogenic/likely pathogenic (P/LP) variants were identified in 125 patients (14.9%), of which 114 (13.6%) were mutations of SNV/INDEL and 11 (1.3%) were CNV. Overall, 46 patients (5.5%) carried mutations of hereditary RCC syndrome-associated genes such as VHL (13, 1.5%), FH (13, 1.5%) and FLCN (8, 1.0%). Interestingly, variants in other cancer-predisposition genes not traditionally associated with RCC occurred in 9.4% of the unselected series, including 55 (6.5%) patients carried mutations in DNA damage (DDR)-related genes (e.g., MUTYH, CHEK2 and BRCA1/2) and the other 24 (2.9%) had germline mutations of non-DDR-related genes (e.g., SPINK1 and APC). The median age of patients with mutations of RCC syndrome-associated genes was 38 (range 19-77), while the median age of patients with mutations of other cancer-predisposition genes was 52(range 22-82). Furthermore, in patients older than 46 years, the prevalence of P/LP variants in RCC-associated and non–RCC-associated genes were 1.9% and 6.7%, respectively. Notably, among 125 patients with identified germline mutations, nearly half (56, 44.8%) did not meet the recommended criteria for genetic testing. Conclusions: Our findings confirm a high prevalence of pathogenic germline variants in genes associated with both hereditary RCC and other cancer predispositions in the unselected Chinese RCC population. Current guidelines recommendation for genetic testing seemed not sensitive enough to identify patients with hereditary RCC susceptibility. It is rational to promote genetic testing and expand the range of genes in RCC population with advanced age.

Germline Genetic Testing in Unselected Squamous and Non-Squamous Head and Neck Cancers.

This study describes the prevalence of pathogenic germline variants (PGVs) in head and neck cancer patients, the incremental yield compared to a guideline-based approach to genetic evaluation, and the uptake of family variant testing. Prospective cohort study. Three tertiary academic medical centers. Germline sequencing using an 84-gene screening platform among unselected head and neck cancer patients who received care at Mayo Clinic Cancer Centers between April 2018 and March 2020. Amongst 200 patients, the median age was 62.0 years (Q1, Q3: 55, 71), 23.0% were female, 89.0% white/non-Hispanic, 5.0% Hispanic/Latinx, 6% of another race, and 42.0% had prognostic stage IV disease. The most common subsites were the oropharyngeal (45.0%) and salivary glands (12.0%). The most common histology was squamous cell carcinoma (74.5%). Twenty-one patients (10.5%) had a total of 22 PGVs; 20 of the 21 patients (95.2%) did not meet criteria for testing by current guidelines. Regarding penetrance of the 22 PGVs, 11 were high or moderate (most common PMS2 or HOXB13), and 11 were low or recessive (most common MUTYH, WNR, or RECQL4). One patient had a change in care based on an identified PGV. Family variant testing was completed at a rate of 4.8%. Universal gene panel testing identified a PGV in 10.5% of head and neck cancer patients; almost all would have been missed by current guideline-based testing. One of 21 patients had a treatment change due to their PGV, indicating that head and neck cancer treatment decisions are not yet widely informed by germline alterations. 3 Laryngoscope, 133:3378-3388, 2023.

Prevalence of Pathogenic Germline Variants in Women with Non-Familial Unilateral Triple-Negative Breast Cancer

Introduction: International guidelines recommend genetic testing for women with familial breast cancer at an expected prevalence of pathogenic germline variants (PVs) of at least 10%. In a study sample of the German Consortium for Hereditary Breast and Ovarian Cancer (GC-HBOC), we have previously shown that women with TNBC diagnosed before the age of 50 years but without a family history of breast or ovarian cancer (sTNBC) meet this criterion. The present study investigates the PV prevalence in BRCA1, BRCA2, and nine additional cancer predisposition genes in an extended sTNBC study sample including a cohort of women with a later age at sTNBC diagnosis. Patients and Methods: In 1,600 women with sTNBC (median age at diagnosis: 41 years, range 19–78 years), we investigated the association between age at diagnosis and PV occurrence in cancer predisposition genes using logistic regression. Results: 260 sTNBC patients (16.2%) were found to have a PV in cancer predisposition genes (BRCA1: n = 170 [10.6%]; BRCA2: n = 46 [2.9%], other: n = 44 [2.8%]). The PV prevalence in women diagnosed between 50 and 59 years (n = 194) was 11.3% (22/194). Logistic regression showed a significant increase in PV prevalence with decreasing age at diagnosis (OR 1.41 per 10 years younger age at diagnosis; 95% confidence interval: 1.21–1.65; p < 0.001). The PV prevalence predicted by the model was above 10% for diagnoses before the age of 56.8 years. Conclusion: Based on the data presented, we recommend genetic testing by gene panel analysis for sTNBC patients diagnosed before the age of 60 years. Due to the still uncertain estimate for women with sTNBC diagnosed above the age of 60 years, further studies are needed.

Abstract P056: Germline cancer susceptibility gene testing in unselected patients with soft tissue sarcoma: a multi-center prospective study

Abstract Sarcomas are rare heterogenous mesenchymal tumors with over 75 different subtypes, with varying biology and outcomes, with no clear inciting factor in the vast majority. The germline genetic susceptibility to sarcoma is not very well characterized. Identification of any underlying germline predisposition can have important implications for treatment of patients and screening recommendations for family members. To determine the prevalence of pathogenic germline variants (PGV) in patients with sarcomas, we undertook the Interrogating Cancer Etiology Using Proactive Genetic Testing (INTERCEPT) study, a prospective multi-site study of germline sequencing using a &amp;gt;80-gene next-generation sequencing platform. The study was done at the three Mayo Clinic Cancer Centers between April 1, 2018, and March 31, 2020. Patients were not selected based on stage, family cancer history, ethnicity, or age. Family cascade testing was offered at no charge. Results: 115 adult patients with soft tissue sarcoma were included in the study. The median age was 60 years, 58.5% were male, 81% were White. The anatomical location of the primary tumor included extremities (33.0%), retroperitoneum (18.2%), trunk (12.2%), head and neck (7.8%). Family history of cancer was present in 63% of the study population. Ten patients (8.7%) had a PGV. Thirty percent of the patients with PGV had stage IV sarcoma (3/10), and 70% (7/10) had earlier stage sarcoma (stages I-III). Among patients who were found to have a variant of uncertain significance (VUS), 40% (22/55) had stage IV sarcoma and 60% (33/55) had earlier stage disease. Of the 10 patients with PGV, high to medium penetrance gene abnormalities were identified in 8 patients (80%) involving TP53 (3), BRCA1 (1), SDHA (1), ATM (2) and heterozygous deletion of NBN (1) genes. Of these PGV, gene deletions were observed in 6/10 while missense variants comprised the remaining 4. The vast majority of the PGV (70%) would not have been identified using the current guidelines utilizing the 2018 or 2020 National Comprehensive Cancer Network (NCCN), National Society of Genetic Counselors (NSGC) or American College of Medical Genetics and Genomics. Conclusion: In this prospective, multi-site study comprising over 100 patients with diverse sarcomas, unselected germline testing identified a PGV in 1 in 11 patients (8.7%) with the majority of these not being detected using current standard of care guidelines for genetic testing. Because of the rarity of sarcomas, in addition to limited effective treatment options for advanced disease, large scale germline testing in sarcomas represents a potentially impactful strategy to assess therapeutic options and for assessment of familial risk. Citation Format: Isaak Ailts, Michael A. Golafshar, Katie L. Kunze, Margaret Klint, Kathleen Barrus, Samuel Nussbaum, Edward Esplin, Brandie Leach, Sarah Young, Niloy Jewel Samadder, Mahesh Seetharam. Germline cancer susceptibility gene testing in unselected patients with soft tissue sarcoma: a multi-center prospective study. [abstract]. In: Proceedings of the AACR Special Conference: Precision Prevention, Early Detection, and Interception of Cancer; 2022 Nov 17-19; Austin, TX. Philadelphia (PA): AACR; Can Prev Res 2023;16(1 Suppl): Abstract nr P056.

Prevalence of pathogenic germline variants in the circulating tumor DNA testing

BackgroundSomatic and germline variants are not distinguishable by circulating tumor DNA (ctDNA) testing without analyzing non-tumor samples. Although confirmatory germline testing is clinically relevant, the criteria for selecting presumed germline variants have not been established in ctDNA testing. In the present study, we aimed to evaluate the prevalence of pathogenic germline variants in clinical ctDNA testing through their variant allele fractions (VAFs).MethodsA total of consecutive 106 patients with advanced solid tumors who underwent ctDNA testing (Guardant360®) between January 2018 and March 2020 were eligible for this study. To verify the origin of pathogenic variants reported in ctDNA testing, germline sequencing was performed using peripheral blood DNA samples archived in the Clinical Bioresource Center in Kyoto University Hospital (Kyoto, Japan) under clinical research settings.ResultsAmong 223 pathogenic variants reported in ctDNA testing, the median VAF was 0.9% (0.02–81.8%), and 88 variants with ≥ 1% VAFs were analyzed in germline sequencing. Among 25 variants with ≥ 30% VAFs, seven were found in peripheral blood DNA (BRCA2: n = 6, JAK2: n = 1). In contrast, among the 63 variants with VAFs ranging from 1 to < 30%, only one variant was found in peripheral blood DNA (TP53: n = 1). Eventually, this variant with 15.6% VAF was defined to be an acquired variant, because its allelic distribution did not completely link to those of neighboring germline polymorphisms.ConclusionOur current study demonstrated that VAFs values are helpful for selecting presumed germline variants in clinical ctDNA testing.

Prevalence of Cancer Predisposition Germline Variants in Male Breast Cancer Patients: Results of the German Consortium for Hereditary Breast and Ovarian Cancer.

Simple SummaryMale breast cancer (mBC) is a rare disease associated with a high prevalence of pathogenic germline variants (PVs) in the BRCA2 gene. However, data regarding other breast cancer (BC) predisposition genes are limited or conflicting. We investigated the prevalence of PVs in BRCA1/2 and 23 other cancer predisposition genes using an overall study sample of 614 patients with mBC. A high proportion of patients with mBC carried pathogenic germline variants in BRCA2 (23.0%, 142/614) and BRCA1 (4.6%, 28/614). A BRCA1/2 PV prevalence of 11.0% was identified in patients with mBC without a family history of breast and/or ovarian cancer. Patients with BRCA1/2 PVs did not show an earlier disease onset than those without. Case-control analyses revealed significant associations of protein-truncating variants in BRCA1, BRCA2, CHEK2, PALB2, and ATM with mBC. Our findings support the benefit of multi-gene panel testing in patients with mBC.Male breast cancer (mBC) is associated with a high prevalence of pathogenic variants (PVs) in the BRCA2 gene; however, data regarding other BC predisposition genes are limited. In this retrospective multicenter study, we investigated the prevalence of PVs in BRCA1/2 and 23 non-BRCA1/2 genes using a sample of 614 patients with mBC, recruited through the centers of the German Consortium for Hereditary Breast and Ovarian Cancer. A high proportion of patients with mBC carried PVs in BRCA2 (23.0%, 142/614) and BRCA1 (4.6%, 28/614). The prevalence of BRCA1/2 PVs was 11.0% in patients with mBC without a family history of breast and/or ovarian cancer. Patients with BRCA1/2 PVs did not show an earlier disease onset than those without. The predominant clinical presentation of tumor phenotypes was estrogen receptor (ER)-positive, progesterone receptor (PR)-positive, and HER2-negative (77.7%); further, 10.2% of the tumors were triple-positive, and 1.2% were triple-negative. No association was found between ER/PR/HER2 status and BRCA1/2 PV occurrence. Comparing the prevalence of protein-truncating variants (PTVs) between patients with mBC and control data (ExAC, n = 27,173) revealed significant associations of PTVs in both BRCA1 and BRCA2 with mBC (BRCA1: OR = 17.04, 95% CI = 10.54–26.82, p < 10−5; BRCA2: OR = 77.71, 95% CI = 58.71–102.33, p < 10−5). A case-control investigation of 23 non-BRCA1/2 genes in 340 BRCA1/2-negative patients and ExAC controls revealed significant associations of PTVs in CHEK2, PALB2, and ATM with mBC (CHEK2: OR = 3.78, 95% CI = 1.59–7.71, p = 0.002; PALB2: OR = 14.77, 95% CI = 5.02–36.02, p < 10−5; ATM: OR = 3.36, 95% CI = 0.89–8.96, p = 0.04). Overall, our findings support the benefit of multi-gene panel testing in patients with mBC irrespective of their family history, age at disease onset, and tumor phenotype.

Germline Cancer Testing in Unselected Patients with Gastric and Esophageal Cancers: A Multi-center Prospective Study

Background and AimsTo determine prevalence and clinical utility of pathogenic germline variants (PGV) in gastric and esophageal cancer patients using universal genetic testing approach.MethodsWe undertook a prospective study of germline sequencing using an > 80 gene next-generation sequencing platform among patients with gastric and esophageal cancers receiving care at Mayo Clinic Cancer Center between April 1, 2018, and March 31, 2020. Patients were not selected based on cancer stage, family history of cancer, ethnicity, or age. Family cascade testing was offered at no cost.ResultsA total of 96 patients were evaluated. Median age was 66 years, 80.2% were male, 89.6% were white. Nearly 39% of the cohort had esophageal cancer, 35.4% gastric cancer and 26% gastroesophageal junction cancers. Approximately half (52%) of the patients had metastatic disease. Pathogenic germline variants (PGV) were detected in 15.6% (n = 15) patients. The prevalence of PGV was 10.8% in esophageal cancer, 17.6% in gastric cancer and 20% in gastroesophageal cancer. Eighty percent of patients with a positive result would not have been detected by screening with standard guidelines for genetic testing. Most PGV detected included genes with high and moderate penetrance related to DNA damage response including BRCA1, BRCA2, PALB2 and ATM.ConclusionsUniversal multi-gene panel testing in gastric and esophageal cancers was associated with detection of heritable mutations in 15% of patients. The majority of PGV would not be detected with current screening guidelines and are related to DNA damage response.

Germline Cancer Susceptibility Gene Testing in Unselected Patients with Hepatobiliary Cancers: A Multi-Center Prospective Study.

Data from germline testing in unselected patients with hepatobiliary cancers are limited. Identification of germline predisposition can have important implications on cancer treatment and family counseling. To determine prevalence of pathogenic germline variants (PGV) in patients with hepatobiliary cancer, we undertook a prospective multi-site study of germline sequencing using a >80-gene next-generation sequencing platform among patients with hepatobiliary cancers receiving care at Mayo Clinic Cancer Centers between April 1, 2018 and March 31, 2020. Patients were not selected on the basis of stage, family cancer history, ethnicity, or age. Family cascade testing was offered at no cost. Of 205 patients, the median age was 65 years, 58.5% were male, 81% were White, and 64.4% had cholangiocarcinoma, 21.5% hepatocellular carcinoma, 7.8% gallbladder cancer, and 4.3% carcinoma of ampulla of Vater. PGV were found in 15.6% (n = 32) of patients, including 23 (71%) in moderate and high penetrance cancer susceptibility genes. A total of 75% of patients with a positive result would not have been detected using guidelines for genetic evaluation. Prevalence of PGV was 15.7% in intrahepatic cholangiocarcinoma, 17% in extrahepatic cholangiocarcinoma, 15.9% in hepatocellular cancer, and 33% in carcinoma of ampulla of Vater. On the basis of these genetic findings, 55% were potentially eligible for approved precision therapy and/or clinical treatment trials. Universal multi-gene panel testing in hepatobiliary cancers was associated with detection of heritable mutations in over 15% of patients most of whom would not have been tested using current guidelines. Germline testing should be considered in all patients with hepatobiliary cancers. PREVENTION RELEVANCE: Universal multi-gene testing in hepatobiliary cancers was associated with heritable mutations in over 15% of patients, most of whom would not have been tested using current guidelines. 55% were potentially eligible for approved precision therapy and/or clinical treatment trials. Germline testing should be considered in all patients with hepatobiliary cancers.

Unexpected High Frequency of Pathogenic Germline Variants in Older Adults with Primary Myelodysplastic Syndrome

Background: Germline predisposition is increasingly being recognised in myeloid neoplasms (MN) including primary myelodysplastic syndrome. An unequivocal diagnosis of germline predisposition carries actionable considerations for patient management including donor stem cell source for allogeneic transplantation, dose-reduction of conditioning regimes and screening for extra-hematological disease (such as pulmonary abnormalities in patients with telomere biology disorders). In addition, the identification of MDS predisposition syndromes can avoid misdiagnosis (for example, distinguishing idiopathic thrombocytopenic purpura from thrombocytopenia due to RUNX1 germline variant). However, the prevalence of pathogenic germline variants (PGVs) in unselected pMDS patients presenting at older age remains unknown.Aim: This study assesses frequency and type of pathogenic germline variants in MDS patients and compares with age matched healthy controls and patients with other cancers.Method: We analysed 68 known cancer predisposition genes in germline samples of 146 samples from myeloid neoplasms. Study included primary MDS (n=51) and MDS diagnosed in cancer survivors with (n=77) or without prior exposure to cytotoxic therapy (n=18). Using uniform American College of Medical Genetics and Genomics (ACMG) guidelines for annotating germline mutation, we also compared the frequency of pathogenic germline variants in the same genes with patients with single cancer and age-match healthy controls (>70 years).Results: Pathogenic germline variants (PGVs) were identified in 19% (28/146) patients compared to 4% and 3% patients with single cancer and age-matched controls respectively (P<0.0001) (Fig. 1A). Median age at diagnosis was similar between MN patients with or without PGVs [66 years (19-81) vs. 70 years (33-87); P=0.06]. PGVs were most frequent in DDX41 (n=7, 33%) followed by BRCA1 (n=2, 10%), GATA2 (n=2; 10%) and TP53 (n=2; 10%) (Fig.1B). We also identified pathogenic copy number variations (CNV) in 4 patients. The distribution of PGVs was also different, with DDX41 PGVs absent in single cancers and more prevalent in MN than age-matched controls (35% vs. 4%, P<0.001). The frequency of PGV was not significantly different between P-MN and T-MN/ MC-MN (17% versus 10%, P = 0.32 (Fig.1C). The frequency of PGV was 30%, 6%, 19%, 15% and 18% in patients ≤50, 51-59, 60-69, 70-79 and >80 years of age (Fig. 1D).Phenotypic features such as monocytopenia and mycobacterium infections (MonoMAC; SA460) and personal and family history of pulmonary fibrosis (SA918) were present in only two cases with PGVs. Family history of MDS/AML was present in only in four cases with PGVs, in which PGVs were found in typical myeloid malignancy genes (DDX41, GATA2). Importantly, some patients with family history of solid cancers carried PGVs in genes traditionally associated with solid cancers (e.g. MSH6, NF1, TP53 and BRCA1). SA927 had a PGV in MSH6 and multiple first-degree relatives with solid cancers including colon, renal and brain cancers. Moreover, 41% of adults with hematological disorders and a personal and/or family history of interstitial lung disease had PGVs in telomere biology disorder genes. Hence, family history should not be restricted to hematological disorders, but also solid cancers and non-malignant phenotypes (e.g. hepatic and pulmonary fibrosis). The frequency of PGVs was not different in patients with and without family history of cancer (23% vs. 13%, P=0.32).Conclusion: The frequency of PGVs is significantly high in MN compared to age matched healthy control and other cancer patients. Our observation of a high frequency of PGVs in the older MDS population warrants standardization of germline testing at diagnosis to guide optimal management of patients and their families. [Display omitted] DisclosuresHiwase: Novartis: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees.

Rare germline variants in childhood cancer patients suspected of genetic predisposition to cancer.

Identification of cancer-predisposing germline variants in childhood cancer patients is important for therapeutic decisions, disease surveillance and risk assessment for patients, and potentially, also for family members. We investigated the spectrum and prevalence of pathogenic germline variants in selected childhood cancer patients with features suggestive of genetic predisposition to cancer. Germline DNA was subjected to exome sequencing to filter variants in 1048 genes of interest including 176 known cancer predisposition genes (CPGs). An enrichment burden analysis compared rare deleterious germline CPG variants in the patient cohort with those in a healthy aged control population. A subset of predicted deleterious variants in novel candidate CPGs was investigated further by examining matched tumor samples, and the functional impact of AXIN1 variants was analyzed in cultured cells. Twenty-two pathogenic/likely pathogenic (P/LP) germline variants detected in 13 CPGs were identified in 19 of 76 patients (25.0%). Unclear association with the diagnosed cancer types was observed in 11 of 19 patients carrying P/LP CPG variants. The burden of rare deleterious germline variants in autosomal dominant CPGs was significantly higher in study patients versus healthy aged controls. A novel AXIN1 frameshift variant (Ser321fs) may impact the regulation of β-catenin levels. Selection of childhood cancer patients for germline testing based on features suggestive of an underlying genetic predisposition could help to identify carriers of clinically relevant germline CPG variants, and streamline the integration of germline genomic testing in the pediatric oncology clinic.

Abstract 448: High prevalence of pathogenic germline variants in patients with oncogene-driven non-small cell lung cancer

Abstract BACKGROUND: Preliminary data has highlighted inherited predisposition to lung cancer related to certain genes. The frequency of pathogenic germline variants (PGV) PGV in patients (pts) with lung cancer according to the presence of an oncogenic driver is unknown. We studied the PGV of genes predisposing to cancer in pts with non-small cell lung cancer (NSCLC), and the somatic molecular profile of lung tumors. METHODS: Retrospective study of whole exome sequencing (WES) from tissue biopsies performed in pts with advanced NSCLC enrolled, after signature of the inform consent, in the MOSCATO/MATCH-R trials between 2012 and 2018. Variants were considered as PGVs in the cancer predisposing genes (PMID: 29625052) if they satisfied the following criteria: (i) they had a “PASS” flag in HaplotypeCaller, (ii) were annotated as “Pathogenic” or “Likely Pathogenic” in ClinVar (PMID: 29165669) or InterVar (PMID: 28132688), or (iii) were truncating variants. Somatic driver mutations and Loss of Heterozygocity (LOH) of PGV harboring genes were further evaluated. The overlap to loss of heterozygocity regions was reported only when the variant allele frequency of the PGV was significantly higher than in the normal tissue. Cancer history, clinical and molecular data were retrospectively collected. The somatic mutations (m) in EGFR/BRAF/MET/HER2/KRAS and fusions in ALK/ROS1/RET were also considered for analysis. RESULTS: Among 134 pts, 48% were women, median age was 61 (range 24-83), 45% were nonsmokers, 74% had adenocarcinoma. The most common somatic oncogenic driver alterations were: EGFRm in 44 pts (33%), KRASm in 19 pts (14%), BRAFm in 12 pts (9%) and ALK in 12 pts (9%).PGV were found in 22 out of 152 (15%) cancer-predisposing genes; 4 pts had additional somatic mutations (2) or LOHs (2) in the same genes. 77% of PGVs were in genes which are part of DNA repair pathways including 3.6% nucleotide excision repair (ERCC1/2/3, XPA), 6.5% homologous recombination/Fanconi Anemia: (FANC/A/C/M/D2, BRCA1, RECQL), 2.1% base excision repair (MUTYH, NTHL1), while the others were represented by genes related to cell signaling and metabolism (NF1, MET, ELANE, PRDM9, TRIM37).In the 22 PGV-carriers, 68% had a somatic oncogene-driven alteration (15/22) : EGFRm (n=7; 5 ex19del, 2 ex21(L858R)), KRASm (n=3; 2 G12D, 1 G12V), METm (n=2), HER2m (n=1), ROS1 (n=1) and RET (n=1). PGV were observed in 16% of EGFRm (7/44), 67% of METm (2/3), 15% in KRASm (3/19), 33% of HER2m (1/3), 25% of ROS1 (1/4), 50% of RET (1/2); but no PGV was identified in pts with BRAFVm (12) or ALK (12). CONCLUSION: In our cohort, 15% of pts with NSCLC were PGV-carriers; 68% of PGV-carriers had oncogene-driven tumors, particularly with somatic EGFR mutations. PGV and oncogene-driven lung carcinogenesis need further evaluation. Citation Format: Laura Mezquita, Andrei Iurchenko, Jose Carlos Benitez, Maria Baz, Sergey Nikolaev, David Planchard, Felix Blanc-Durand, Mihaela Aldea, Patricia Martín-Romano, Yohann Loriot, Claudio Nicotra, Maud Ngocamus, Jean-Yves Scoazec, Stefan Michiels, Sophie Postel-Vinay, Julien Viot, Luc Friboulet, Antoine Italiano, Fabrice Andre, Christophe Massard, Jean-Charles Soria, Etienne Rouleau, Daniel Gautheret, Benjamin Besse. High prevalence of pathogenic germline variants in patients with oncogene-driven non-small cell lung 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 448.

Germline Cancer Susceptibility Gene Testing in Unselected Patients With Colorectal Adenocarcinoma: A Multicenter Prospective Study

Hereditary factors play a role in the development of colorectal cancer (CRC). Identification of germlinepredisposition can have implications on treatment and cancer prevention. This study aimedto determine the prevalence of pathogenic germline variants (PGVs) in CRC patients using a universal testing approach, association with clinical outcomes, and the uptake of family variant testing. We performed a prospective multisite study of germline sequencing using a more than 80-gene next-generation sequencing platform among CRC patients (not selected for age or family history) receiving care at Mayo Clinic Cancer Centers between April 1, 2018, and March 31,2020. Of 361 patients, the median age was 57 years (SD, 12.4 y), 43.5% were female, 82% were white, and 38.2% had stage IV disease. PGVs were found in 15.5% (n= 56) of patients, including 44 in moderate- and high-penetrance cancer susceptibility genes. Thirty-four (9.4%) patients had incremental clinically actionable findings that would not have been detected by practice guideline criteria or a CRC-specific gene panel. Only younger age at diagnosis was associated with the presence of PGVs (odds ratio, 1.99; 95% CI, 1.12-3.56). After a median follow-up period of 20.7 months, no differences in overall survival were seen between those with or without a PGV (P= .2). Eleven percent of patients had modifications in their treatment based on genetic findings. Family cascade testing was low (16%). Universal multigene panel testing in CRC was associated with a modest, but significant, detection of heritable mutations over guideline-based testing. One in 10 patients had changes in their management based on test results. Uptake of cascade family testing was low, which is a concerning observation that warrants further study.

Prevalence of pathogenic germline variants in patients with metastatic renal cell carcinoma

Germline pathogenic variants are estimated to affect 3-5% of renal cell carcinoma (RCC) patients. However, higher mutational prevalence in non-clear cell RCC (non-ccRCC) and advanced disease has been suggested. To clarify the prevalence of pathogenic germline variants in metastatic RCC, we sequenced 29 cancer susceptibility genes in 294 unselected metastatic RCC cases plus 21 patients with clinical hereditary features. In 145 tumors, genes frequently mutated in RCC were sequenced and methylation was assessed in selected cases. Germline variants in RCC predisposition genes (FH, VHL) were detected in 1.4% of the unselected metastatic patients, with higher frequency in non-ccRCC versus ccRCC (6.4% and 0.4%; P = 0.0025) and in younger patients (P = 0.036). Among the 315 studied patients, 14% of non-type 1 papillary cases (4 of 28), all metastatic <1 year after diagnosis, carried a FH germline variant with loss of heterozygosity and tumor genome hypermethylation. Variants in other cancer-associated genes (e.g., MUTYH, BRCA2, CHEK2) occurred in 5.1% of the unselected series, with unclear significance for RCC. Our findings confirm a high prevalence of pathogenic germline variants in RCC predisposition genes in metastatic non-ccRCC, and highlight that metastatic patients with papillary type 2 or unconventional histologies compatible with FH would benefit from genetic screening.