Pathogenic Variants In ATM Research Articles

Spectrum of hematological malignancies, clonal evolution and outcomes in 144 Mayo Clinic patients with germline predisposition syndromes.

Germline predisposition syndromes (GPS) result from constitutional aberrations in tumor suppressive and homeostatic genes, increasing risk for neoplasia in affected kindred. In this study, we present clinical and genomic data on 144 Mayo Clinic patients with GPS; 59 evaluated prospectively using an algorithm-based diagnostic approach in the setting of a dedicated GPS/ inherited bone marrow failure syndrome (IBMFS) clinic. Seventy-two (50%) patients had IBMFS (telomere biology disorders-32,Fanconi anemia-18, Diamond Blackfan Anemia - 11, congenital neutropenia-5, Schwachman-Diamond Syndrome-5 and Bloom Syndrome-1), 27 (19%) had GPS with antecedent thrombocytopenia (RUNX1-FPD-15, ANKRD26-6, ETV6-2, GATA1-1, MPL-3), 28 (19%) had GPS without antecedent thrombocytopenia (GATA2 haploinsufficiency-16, DDX41-10, CBL-1 and CEBPA-1) and 17 (12%) had general cancer predisposition syndromes (ataxia telangiectasia-7, heterozygous ATM variants-3, CHEK2-2, TP53-2, CDK2NA-1, NF1-1 and Nijmegen Breakage Syndrome-1). Homozygous and heterozygous ATM pathogenic variants were exclusively associated with lymphoproliferative disorders (LPD), while DDX41 GPS was associated with LPD and myeloid neoplasms. The use of somatic NGS-testing identified clonal evolution in GPS patients, with ASXL1, RAS pathway genes, SRSF2 and TET2 being most frequently mutated. Fifty-two (91%) of 59 prospectively identified GPS patients had a change in their management approach, including additional GPS-related screening in 42 (71%), referral for allogenic HSCT workup and screening of related donors in 16 (27%), medication initiation and selection of specific conditioning regimens in 14 (24%), and genetic counseling with specific intent of fertility preservation and preconceptual counseling in 10 (17%) patients; highlighting the importance of dedicated GPS screening, detection and management programs for patients with hematological neoplasms.

Compound heterozygous variants including a novel copy number variation in a child with atypical ataxia-telangiectasia: a case report

BackgroundAtaxia-telangiectasia is a rare autosomal recessive, neurodegenerative disorder caused by alterations in the ATM gene. The majority of ATM pathogenic variants are frameshift or nonsense variants which are predicted to truncate the whole ATM protein. Herein, we report on an ataxia telangiectasia child with atypical phenotype who was identified as compound heterozygous for two ATM variants involving a previously described pathogenic single nucleotide variation (SNV) and a novel copy number variation (CNV).Case presentationA 6-year-old boy presented with delayed development and oculomotor apraxia. Brain magnetic resonance imaging showed interval development of mild atrophy in the cerebellum. Serum alpha fetoprotein level was in normal range. Next-generation sequencing and single-nucleotide polymorphism array tests were performed. Next-generation sequencing revealed a heterozygous nonsense pathogenic variant in ATM, c.742C > T (p.Arg248Ter) inherited from the father. Single-nucleotide polymorphism array revealed a compound heterozygous CNV, arr[GRCh37] 11q22.3(10851766–108183226) × 1, 31460 bp (exons 24–40 deletion of ATM) inherited from the mother, which was validated by reverse transcription-polymerase chain reaction analysis (RT-PCR). We demonstrated that this variant (NM_000051.4:c.3403_6006del) generated a product of in-frame deletion of exon 24–40 of ATM (p.Ser1135_Gln2002del).ConclusionsThe compound heterozygosity for ATM variants involving a previously described pathogenic SNV and a novel CNV may be associated with the atypical clinical manifestations. This clinical report extends the genetic and phenotypic spectrum of ATM pathogenic variants in atypical ataxia-telangiectasia, thus making implementation of advanced analysis beyond the routine next-generation sequencing an important consideration in diagnosis and rehabilitation services for children with ataxia-telangiectasia.

Breast cancer screening for carriers of ATM, CHEK2, and PALB2 pathogenic variants: A comparative modeling analysis.

10500 Background: Inherited pathogenic variants in ATM, CHEK2, and PALB2 confer moderate to high risks of breast cancer. The optimal approach to screening in these women has not been established. Methods: We used two simulation models from the Cancer Intervention and Surveillance Modeling Network (CISNET) and data from the Cancer Risk Estimates Related to Susceptibility consortium (CARRIERS) to project lifetime breast cancer incidence and mortality in ATM, CHEK2, and PALB2 carriers. We simulated screening with annual mammography from ages 40-74 alone and with annual magnetic resonance imaging (MRI) starting at ages 40, 35, 30, and 25. Joint and separate mammography and MRI screening performance was based on published literature. Lifetime outcomes per 1,000 women were reported as means and ranges across both models. Results: Estimated risk of breast cancer by age 80 was 22% (21-23%) for ATM, 28% (26-30%) for CHEK2, and 40% (38-42%) for PALB2. Screening with MRI and mammography reduced breast cancer mortality by 52-60% across variants (Table). Compared to no screening, starting MRI at age 30 increased life years (LY)/1000 women by 501 (478-523) in ATM, 620 (587-652) in CHEK2, and 1,025 (998-1,051) in PALB2. Starting MRI at age 25 versus 30 gained 9-12 LY/1000 women with 517-518 additional false positive screens and 197-198 benign biopsies. Conclusions: For women with ATM, CHEK2, and PALB2 pathogenic variants, breast cancer screening with MRI and mammography halves breast cancer mortality. These mortality benefits are similar to those for MRI screening for BRCA1/2 mutation carriers and should inform practice guidelines.[Table: see text]

Germline pathogenic variants in cancer predisposition genes among women with invasive lobular cancer of breast.

10581 Background: The prevalence of germline pathogenic variants (PVs) in cancer predisposition genes among women with invasive lobular breast cancer (ILC) and the risk of ILC in PV carriers is not well-defined. Methods: The study included 2,999 women with ILC and 32,544 unaffected controls from a population-based cohort; 3,796 women with ILC and 20,323 women with invasive ductal carcinoma (IDC) undergoing clinical multigene panel testing (clinical cohort); and 125,748 exome sequences from unrelated women without a cancer diagnosis in the gnomAD 3.0 dataset. Frequencies of germline PVs in breast cancer predisposition genes ( ATM, BARD1, BRCA1, BRCA2, BRIP1, CDH1, CHEK2, PALB2, PTEN, RAD51C, RAD51D, and TP53) were compared between women with ILC and unaffected controls in both cohorts and between women with ILC and IDC in the clinical cohort. Results: The frequency of PVs in breast cancer predisposition genes among women with ILC was 6.5% in the clinical cohort and 5.2% in the population-based cohort. In case-control analyses, CDH1 and BRCA2 PVs were associated with high risks of ILC (Odds ratio (OR) > 4), and CHEK2, ATM and PALB2 PVs were associated with moderate (OR = 2-4) risks. BRCA1 PVs and CHEK2 p.Ile157Thr were not associated with clinically relevant risks (OR < 2) of ILC. PV frequencies in these genes in ILC and IDC were similar except for PV frequencies in BRCA1 and CDH1. Conclusions: The study establishes that PVs in ATM, BRCA2, CDH1, CHEK2 and PALB2 are associated with an increased risk of ILC, whereas BRCA1 PVs are not. The similar overall PV frequencies for ILC and IDC suggest that cancer histology should not influence the decision to proceed with genetic testing. While, multigene panel testing may be appropriate for women with ILC, CDH1 should be specifically discussed in the context of low prevalence and attendant gastric cancer risk.

Extended gene panel testing in lobular breast cancer

Purpose: Lobular breast cancer (LBC) accounts for ~ 15% of breast cancer. Here, we studied the frequency of pathogenic germline variants (PGVs) in an extended panel of genes in women affected with LBC. Methods: 302 women with LBC and 1567 without breast cancer were tested for BRCA1/2 PGVs. A subset of 134 LBC affected women who tested negative for BRCA1/2 PGVs underwent extended screening, including: ATM, CDH1, CHEK2, NBN, PALB2, PTEN, RAD50, RAD51D, and TP53.Results: 35 PGVs were identified in the group with LBC, of which 22 were in BRCA1/2. Ten actionable PGVs were identified in additional genes (ATM(4), CDH1(1), CHEK2(1), PALB2(2) and TP53(2)). Overall, PGVs in three genes conferred a significant increased risk for LBC. Odds ratios (ORs) were: BRCA1: OR = 13.17 (95%CI 2.83–66.38; P = 0.0017), BRCA2: OR = 10.33 (95%CI 4.58–23.95; P < 0.0001); and ATM: OR = 8.01 (95%CI 2.52–29.92; P = 0.0053). We did not detect an increased risk of LBC for PALB2, CDH1 or CHEK2. Conclusion: The overall PGV detection rate was 11.59%, with similar rates of BRCA1/2 (7.28%) PGVs as for other actionable PGVs (7.46%), indicating a benefit for extended panel genetic testing in LBC. We also report a previously unrecognised association of pathogenic variants in ATM with LBC.

CtDNA pathogenic variants (PVs) in homologous recombination repair (HRR) genes in patients with metastatic CRPC.

138 Background: HRR PVs can serve as predictive biomarkers and two PARP inhibitors are approved for metastasic CRPC (mCRPC) pts. Published data are predominantly focused on tissue-based assays, but obtaining tissue from mCRPC pts is problematic. In a large tissue based series (PROfound), 4047 mCRPC pts had tumor samples submitted for genomic testing but only 69% had interpretable results. No data were published from PROfound enumerating pts without available tissue to submit. Herein we assess frequency of PVs from selected HRR genes using a ctDNA assay. Methods: 292 mCRPC pts at Tulane Cancer Center were assessed for detectable HRR ctDNA changes using the Guardant 360 assay (which assesses the HRR genes BRCA1, BRCA2, and ATM). Results: 20/292 (6.8%) pts had a PV in ATM. However only 4/292 (1.4%) had &gt; 1% mutant allelic fraction. Germline testing occurred in 18/20 of the ctDNA ATM PV pts and 0/18 had a germline PV. The PROfound series had 6.3% somatic PVs in ATM. 18/292 pts (6.2%) had a PV in BRCA2 and 12/292 (4.1%) had a mutant allelic fraction of &gt; 1%. Germline testing was performed in 17/18 with BRCA2 ctDNA PVs and 9/17 had germline PVs. The PROfound series had 9.7% somatic BRCA2 PVs. BRCA1 PVs were detected in 6/292 (2.1%) pts and 3/292 (1%) had a mutant allelic fraction &gt; 1%. 6/6 of the ctDNA PVs has germline testing and 1/6 had a BRCA1 PV. The PROfound series had 1.3% somatic PVs in BRCA1. Conclusions: Using ctDNA essay, it is feasible to measure PVs in only a small subset of HRR genes in mCRPC pts. These assays fail to detect deep deletions, a known and important mechanism of HRR gene loss. The ctDNA mutant allelic fractions are often low. The ability of ctDNA PVs using this assay to predict treatment effects are unknown.

Abstract PD10-09: Development of a breast cancer risk assessment model for ATM mutation carriers incorporating tyrer-cuzick and a polygenic risk score (PRS)

Abstract Background: Germline pathogenic variants (PVs) in the moderate penetrance ATM gene confer a roughly 2-fold increased risk for breast cancer. Currently, any woman with an ATM PV meets the &amp;gt;20% lifetime risk threshold for consideration of relatively aggressive screening recommendations, which include initiating screening at younger ages and consideration of breast MRI. We and others have previously shown that breast cancer risks for women with inherited PVs in many hereditary breast cancer genes can be adjusted using PRS data, breast cancer family history, and other clinical information. Herein we show the development of a comprehensive breast cancer risk model for ATM PV carriers incorporating a previously described 86-variant PRS along with family history/clinical information captured by Tyrer-Cuzick V7.02. Methods: This IRB-approved study included de-identified clinical records from 353,809 women of European ancestry who were tested clinically for hereditary cancer risk with a multi-gene panel. Model development analyzed ATM PV carriers (N=2,666) and women negative for breast cancer gene PVs (N=351,143) who were tested between September 2013 and November 2019 (July 2019 for non-carriers). Women with the unusually high risk ATM c.7271 allele were excluded from analysis. Risk estimates incorporating ATM, PRS, and Tyrer-Cuzick were calculated using a fixed-stratified method that accounted for correlations between risk factors in a manner equivalent to multivariable co-estimation. Risk stratification was assessed in an independent cohort of ATM carriers (N=272) who were tested after November 2019 and were not included in model development. Results: We detected significant positive correlation of ATM status with breast cancer family history (p=1.6×10−7). Within ATM PV carriers, we observed positive yet non-significant (at alpha &amp;lt;0.05) correlation between PRS and breast cancer family history (p=0.10); joint effects were co-estimated using the fixed-stratified method. After adjusting for multiple testing, we found no evidence of interaction of ATM status with clinical factors, or PRS with clinical factors within ATM carriers. In an independent cohort, 30.1% of ATM carriers were categorized as having low breast cancer risk (&amp;lt;20%), 58.5% as moderate risk (20-50%), and 11.4% as high risk (&amp;gt;50%). Conclusions: In ATM PV carriers, our comprehensive model allowed for differentiation of ATM PV carriers into low, moderate, and high breast cancer risk categories. Precision breast cancer risk estimation may inform individualized clinical screening and prevention strategies. Citation Format: Shannon Gallagher, Elisha Hughes, Eric Rosenthal, Allison W. Kurian, Susan Domchek, Judy Garber, Braden Probst, Brian Morris, Placede Tshiaba, Benjamin Roa, Thomas P. Slavin, Susanne Wagner, Jeffrey N. Weitzel, Alexander Gutin, Jerry S. Lanchbury, Mark E. Robson. Development of a breast cancer risk assessment model for ATM mutation carriers incorporating tyrer-cuzick and a polygenic risk score (PRS) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD10-09.

A Population-Based Study of Genes Previously Implicated in Breast Cancer

BackgroundPopulation-based estimates of the risk of breast cancer associated with germline pathogenic variants in cancer-predisposition genes are critically needed for risk assessment and management in women with inherited pathogenic variants.MethodsIn a population-based case–control study, we performed sequencing using a custom multigene amplicon-based panel to identify germline pathogenic variants in 28 cancer-predisposition genes among 32,247 women with breast cancer (case patients) and 32,544 unaffected women (controls) from population-based studies in the Cancer Risk Estimates Related to Susceptibility (CARRIERS) consortium. Associations between pathogenic variants in each gene and the risk of breast cancer were assessed.ResultsPathogenic variants in 12 established breast cancer–predisposition genes were detected in 5.03% of case patients and in 1.63% of controls. Pathogenic variants in BRCA1 and BRCA2 were associated with a high risk of breast cancer, with odds ratios of 7.62 (95% confidence interval [CI], 5.33 to 11.27) and 5.23 (95% CI, 4.09 to 6.77), respectively. Pathogenic variants in PALB2 were associated with a moderate risk (odds ratio, 3.83; 95% CI, 2.68 to 5.63). Pathogenic variants in BARD1, RAD51C, and RAD51D were associated with increased risks of estrogen receptor–negative breast cancer and triple-negative breast cancer, whereas pathogenic variants in ATM, CDH1, and CHEK2 were associated with an increased risk of estrogen receptor–positive breast cancer. Pathogenic variants in 16 candidate breast cancer–predisposition genes, including the c.657_661del5 founder pathogenic variant in NBN, were not associated with an increased risk of breast cancer.ConclusionsThis study provides estimates of the prevalence and risk of breast cancer associated with pathogenic variants in known breast cancer–predisposition genes in the U.S. population. These estimates can inform cancer testing and screening and improve clinical management strategies for women in the general population with inherited pathogenic variants in these genes. (Funded by the National Institutes of Health and the Breast Cancer Research Foundation.)

Germline Pathogenic Variants in the Ataxia Telangiectasia Mutated (ATM) Gene are Associated with High and Moderate Risks for Multiple Cancers.

Pathogenic variants (PVs) in ATM are relatively common, but the scope and magnitude of risk remains uncertain. This study aimed to estimate ATM PV cancer risks independent of family cancer history. This analysis included patients referred for hereditary cancer testing with a multi-gene panel (N = 627,742). Cancer risks for ATM PV carriers (N = 4,607) were adjusted for family history using multivariable logistic regression and reported as ORs with 95% confidence intervals (CIs). Subanalyses of the c.7271T>G missense PV were conducted. Moderate-to-high risks for pancreatic (OR, 4.21; 95% CI, 3.24-5.47), prostate (OR, 2.58; 95% CI, 1.93-3.44), gastric (OR, 2.97; 95% CI, 1.66-5.31), and invasive ductal breast (OR, 2.03; 95% CI, 1.89-2.19) cancers were estimated for ATM PV carriers. Notably, c.7271T>G was associated with higher invasive ductal breast cancer risk (OR, 3.76; 95% CI, 2.76-5.12) than other missense and truncating ATM PVs. Low-to-moderate risks were seen for ductal carcinoma in situ (OR, 1.80; 95% CI, 1.61-2.02), male breast cancer (OR, 1.72; 95% CI, 1.08-2.75), ovarian cancer (OR, 1.57; 95% CI, 1.35-1.83), colorectal cancer (OR, 1.49; 95% CI, 1.24-1.79), and melanoma (OR, 1.46; 95% CI, 1.18-1.81). ATM PVs are associated with multiple cancer risks and, while professional society guidelines support that carriers are eligible for increased breast and pancreatic cancer screening, increased screening for prostate and gastric cancer may also be warranted. c.7271T>G is associated with high risk for breast cancer, with a 3- to 4-fold risk increase that supports consideration of strategies for prevention and/or early detection. PREVENTION RELEVANCE: This study estimated risks for multiple cancers associated with ATM pathogenic variants independent of family history. These results indicate that some common variants may be associated with higher breast cancer risks than previously appreciated and increased screening for prostate and gastric cancer may be warranted for carriers of ATM pathogenic variants.

A Collaborative Effort to Define Classification Criteria for ATM Variants in Hereditary Cancer Patients.

Gene panel testing by massive parallel sequencing has increased the diagnostic yield but also the number of variants of uncertain significance. Clinical interpretation of genomic data requires expertise for each gene and disease. Heterozygous ATM pathogenic variants increase the risk of cancer, particularly breast cancer. For this reason, ATM is included in most hereditary cancer panels. It is a large gene, showing a high number of variants, most of them of uncertain significance. Hence, we initiated a collaborative effort to improve and standardize variant classification for the ATM gene. Six independent laboratories collected information from 766 ATM variant carriers harboring 283 different variants. Data were submitted in a consensus template form, variant nomenclature and clinical information were curated, and monthly team conferences were established to review and adapt American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) criteria to ATM, which were used to classify 50 representative variants. Amid 283 different variants, 99 appeared more than once, 35 had differences in classification among laboratories. Refinement of ACMG/AMP criteria to ATM involved specification for twenty-one criteria and adjustment of strength for fourteen others. Afterwards, 50 variants carried by 254 index cases were classified with the established framework resulting in a consensus classification for all of them and a reduction in the number of variants of uncertain significance from 58% to 42%. Our results highlight the relevance of data sharing and data curation by multidisciplinary experts to achieve improved variant classification that will eventually improve clinical management.

Racial and Ethnic Differences in Multigene Hereditary Cancer Panel Test Results for Women With Breast Cancer.

To evaluate the racial and ethnic differences in prevalence of germline pathogenic variants (PVs) and the effect of race and ethnicity on breast cancer (BC) risk among carriers, results of multigene testing of 77 900 women with BC (non-Hispanic White [NHW] = 57 003; Ashkenazi-Jewish = 4798; Black = 6722; Hispanic = 5194; and Asian = 4183) were analyzed, and the frequency of PVs in each gene were compared between BC patients (cases) and race- and ethnicity-matched gnomAD reference controls. Compared with NHWs, BRCA1 PVs were enriched in Ashkenazi-Jews and Hispanics, whereas CHEK2 PVs were statistically significantly lower in Blacks, Hispanics, and Asians (all 2-sided P < .05). In case-control studies, BARD1 PVs were associated with high risks (odds ratio > 4.00) of BC in Blacks, Hispanics, and Asians; ATM PVs were associated with increased risk of BC among all races and ethnicities except Asians, whereas CHEK2 and BRIP1 PVs were associated with increased risk of BC among NHWs and Hispanics only. These findings suggest a need for personalized management of BC risk in PV carriers based on race and ethnicity.

Functional Confirmation of DNA Repair Defect in Ataxia Telangiectasia (AT) Infants Identified by Newborn Screening for Severe Combined Immunodeficiency (NBS SCID)

The introduction of newborn screening for severe combined immunodeficiencies (NBS SCID) in 2010 was a significant public health milestone. Although SCID was the primary target, several other conditions associated with severe T-cell lymphopenia have subsequently been identified as secondary targets. The differential diagnosis in infants with an abnormal T-cell receptor excision circle result on NBS SCID who do not meet criteria for typical SCID is often broad, and often the evaluation of these conditions requires immunological and functional testing, in conjunction with genetic analysis, to obtain an accurate diagnosis and develop an appropriate management and treatment plan. We describe here 3 infants identified by NBS SCID, who required additional workup as they did not have a typical SCID phenotype and meet the relevant diagnostic criteria. Genetic testing identified pathogenic variants in ATM in all 3 patients, and the pathogenicity of the variants was confirmed by a functional flow cytometry assay. The patients underwent immunological and genetic workup to identify an underlying cause of their abnormal NBS SCID. Ataxia telangiectasia (AT) was suspected based on clinical and family history, and immunological analyses. The diagnosis was confirmed in all patients with a rapid functional flow cytometric assay and genetic testing. A rapid functional flow cytometry assay was used as a diagnostic and confirmatory tool, in conjunction with genetic testing, to make a diagnosis of AT. Experimental validation of the causal relationship between genotype and phenotype allowed for expeditious diagnosis, which facilitated early discussions with families regarding prognosis, treatment, and management. Even with increased rapidity and access to genetic results, functional testing is required for clinical diagnosis in infants identified by NBS SCID who do not fit into the classic categories or have novel genetic variants to confirm the diagnosis. Consideration should be given to the use of functional assays as an essential component of an integrated evaluation to characterize the genetics and mechanisms of inborn errors of immunity.

Clinicopathologic features of invasive breast cancer (BC) diagnosed in carriers of germline PALB2, CHEK2 and ATM pathogenic variants.

1549 Background: While germline pathogenic variants (PVs) in BRCA1/2 account for a large proportion of hereditary breast cancer (BC), PVs in PALB2, CHEK2 and ATM are increasingly detected. However, the phenotype and clinical features of invasive BC with these PVs have not been fully described. Methods: We identified patients with a PV or likely PV in PALB2, CHEK2 or ATM tested clinically at Stanford between 2014 - 2019 who provided informed consent to be included in a prospective cancer genetics registry. Data on baseline demographics, genetic testing history, and clinicopathologic features of diagnosed BC were collected. For patients with a subsequent diagnosis of metastatic BC, we calculated disease-free interval (DFI). Results: 130 patients met inclusion criteria for analysis: ATM (N=39), CHEK2 (N=58), PALB2 (N=33). Nearly all (98.5%) were women, with 2 male BC in ATM carriers. Non-Hispanic White ethnicity was most common in ATM (64.1%, 95% CI 48.4%-77.3%) and CHEK2 carriers (69.0%, 95% CI 56.1%-79.4%), but comprised only 39.4% (95% CI 24.7%-56.4%) in PALB2 carriers. Asian/Pacific Islander (24.2%, 95% CI 12.6%-41.3%) and Hispanic (30.3%, 95% CI 17.3%-47.5%) ethnicities were enriched among PALB2 mutation carriers. In total, 97.7% learned of their PV status only after a preceding diagnosis of BC and 43.1% were diagnosed with BC at age ≤ 45. Data regarding invasive BC subtypes, incidence of subsequent primary BC, and metastatic recurrence are listed below in the table. Additional data on stage, grade and sites of metastatic spread will be presented. Conclusions: We observed clinically important differences in the spectrum of BC subtypes among carriers of ATM, CHEK2 and PALB2 PVs, in addition to racial/ethnic differences with Asian/Pacific Islander and Hispanic ethnicity enriched among carriers of PALB2 PVs. [Table: see text]

Germline mutations in Brazilian pancreatic carcinoma patients.

e16749 Background: Pancreatic cancer has the prospect of becoming the second leading cause of cancer death by 2030. The NCCN Guidelines recommend genetic testing for all patients with pancreatic cancer, however, the spectrum of germline mutations has not been extensively evaluated because recent studies with genetic testing have explored only a limited number of genes and have focused predominantly on Caucasian populations. Therefore, our objective is to evaluate the frequency and spectrum of germline mutations in unselected patients with pancreatic cancer in a multiethnic population. Methods: Patients from Instituto do Câncer do Estado de São Paulo (Brazil) with histopathological diagnosis of non-endocrine pancreatic carcinoma were included, regardless of the family history of cancer. These patients answered a life habits and family history of cancer questionnaire and supplied blood for the Next Generation Sequencing (MiSeq platform) with the TruSight Hereditary Cancer panel (Illumina), which includes 115 cancer predisposing genes. Variant analysis was performed with the VarStation, a Brazilian tool that offers post-sequencing computational support and aid for clinical interpretation. Results: To the present moment, 77 patients were evaluated. The mean age of the patients was 62 years (27-83), among whom, 13% with young age (≤50 years) and 47 women (61%). Thirty-eight patients (49%) reported cases of cancer in first-degree relatives. Regarding risk factors, 41 patients (53%) reported smoking, 19 (25%) alcohol ingestion and 20 (26%) had obesity. Seven out of 77 patients presented pathogenic variants in ATM (n = 2) , CHEK2, FANCM (n = 2) or PALB2 (n = 2) genes. Two of these patients ( CHEK2 and FANCM) had early onset pancreatic cancer (≤45 years), both denied smoking habit and family history of cancer in 1st degree relatives. Two patients, who were ATM mutation carriers, reported 1st or 2nd degree relatives with cancer and are alive after 4 and 8 years of diagnosis. Conclusions: In this unselected group of pancreatic cancer patients, 15% were young, almost half reported first-degree relatives with cancer and 9% were carriers of pathogenic variants in genes related with the homologous recombination DNA repair.

Abstract P6-08-07: Polygenic breast cancer risk modification in carriers of high and intermediate risk gene mutations

Abstract Background: The incorporation of polygenic scores into breast cancer risk assessment models has led to improved risk management for women of European ancestry. However, few studies have examined the extent to which polygenic scores modify risk for carriers of breast cancer susceptibility gene mutations. Current literature suggests that a 77-SNP polygenic score developed from large, mainly non-carrier general population studies can stratify breast cancer risk for carriers of the CHEK2 founder mutation 1100delC with the same effect size observed for non-carriers. Consequently, several groups have modified risk estimates for carriers of other pathogenic variants by applying published effect estimates from non-carriers. In a recent study, a similar 88-SNP polygenic score showed reduced effectiveness in BRCA1 and BRCA2 carriers compared to non-carriers. This highlights the need for more information on polygenic score performance among women who carry pathogenic variants in ATM or PALB2, or in CHEK2 other than the 1100delC founder mutation. We previously described an 86-SNP polygenic residual risk score (RRS) that characterizes genetic risk which is not due to high- or moderate-penetrance breast cancer gene mutations. Here, we present pre-specified independent validation of the RRS for BRCA1, BRCA2, CHEK2, ATM and PALB2 carriers.Methods: This IRB-approved study included 152,172 women of European ancestry who were tested clinically for hereditary cancer risk with a multi-gene panel. The RRS was evaluated separately for carriers of BRCA1 (N=2,249), BRCA2 (N=2,638), CHEK2 (N=2,564), ATM (N=1,445) and PALB2 (N=906), and for mutation-free women (N=141,160). Clinical information was obtained from test requisition forms. Multivariable logistic regression was used to examine the association of RRS with invasive breast cancer after accounting for age and family cancer history. Effect sizes, expressed as standardized odds ratios (ORs) with 95% confidence intervals (CIs), were assessed for carriers of each gene and for non-carriers. Results: RRS was strongly associated with breast cancer risk in each of the BRCA1, BRCA2, CHEK2, ATM and PALB2 carrier populations (p&amp;lt;10−4). Risk modification in CHEK2 carriers (OR 1.49; CI 1.36-1.64) was consistent with that observed in non-carriers (OR 1.47; CI 1.45-1.49). CHEK2 carriers in the highest RRS quintile had approximately 1.7-fold higher risk than the middle quintile (OR 1.67; CI 1.26 - 2.20), and the lowest quintile had risk lowered by factor of 0.59 (OR 0.59; CI 0.44 - 0.80). We observed reduced modification similar to existing literature for carriers of BRCA1 (OR 1.20; CI 1.10-1.32) and BRCA2 (OR 1.23; CI 1.12-1.34). Odds ratios for ATM (1.37; CI 1.21-1.55) and PALB2 (1.34; CI 1.16-1.55) had wide confidence intervals that overlapped those for the other carrier populations. Discussion: The RRS significantly modifies risk for carriers of BRCA1, BRCA2, CHEK2, ATM and PALB2 mutations albeit with apparently different effect sizes. These results indicate that risk estimates employing polygenic scores may need to be derived separately for each gene. Given the modest effect on BRCA1 and BRCA2 risk and the substantial risks conferred by these genes even with lower RRS, the clinical implications of polygenic modification in this setting are yet to be determined. In CHEK2 carriers, we observed strong polygenic modification similar to that achieved for non-carriers. For ATM and PALB2, larger studies are needed to refine polygenic effect size estimates. Comprehensive risk assessment combining RRS with family cancer history and other risk factors has potential to refine risk estimates and facilitate decision-making for women with mutations in moderate penetrance genes. Citation Format: Shannon Gallagher, Elisha Hughes, Susanne Wagner, Placede Tshiaba, Eric Rosenthal, Benjamin B. Roa, Allison Kurian, Susan Domchek, Judy Garber, Johnathan M. Lancaster, Jeffrey Weitzel, Alexander Gutin, Jerry S. Lanchbury, Mark Robson. Polygenic breast cancer risk modification in carriers of high and intermediate risk gene mutations [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-08-07.

Radiographic Surveillance of Patients with Non-BRCA1/2 Pathogenic Variants.

The National Comprehensive Cancer Network (NCCN) developed clinical practice guidelines for germline pathogenic variants in highly penetrant genes, such asTP53andPTEN, and in moderately penetrant genes, such asCHEK2, ATM andPALB2. Whether the practice of radiographic surveillance of patients with pathogenic variants in genes other than BRCA1/2 complies with current NCCN guidelines remains unclear. Retrospective review of patients identified with pathogenic variants in genes other than BRCA1/2 from 2007 through 2017 to determine if radiographic surveillance was in accordance with NCCN guidelines for mammography and consideration of magnetic resonance imaging (MRI). Exclusions included variants of unknown significance, pathogenic variants not associated with an increased risk of breast cancer, and previous breast cancer diagnosis. After exclusions, 35 patients with pathogenic variants in ATM, CDH1, CHEK2, NBN, PALB2, PTEN, and STK11 genes were reviewed to assess whether radiographic surveillance was in accordance with NCCN guidelines. Guidelines for those with variants in ATM, CHEK2 and NBN includes annual mammography with tomosynthesis and consideration of breast MRI at age 40, variants in CDH1 and PALB2 at age 30, variants in PTEN at age 30-35 or 5-10 years before the earliest family breast cancer, and variants in STK11 at age 25. Of these 35 patients, 11 (31%) received mammography only; 11 (31%) received mammography and MRI, and 13 (37%) received no radiographic surveillance. Two of the 35 (6%) patients who received radiographic surveillance were diagnosed with ductal carcinoma in situ or invasive breast cancer. Thirty-one percent of patients with pathogenic variants in genes other than BRCA1/2 received both mammography and MRI. Thirty-seven percent of patients with these highly penetrant and moderately penetrant genes received no radiographic follow-up, clearly demonstrating an opportunity for improvement.

Histomorphology of pancreatic cancer in patients with inherited ATM serine/threonine kinase pathogenic variants

Germline pathogenic variants in the ATM serine/threonine kinase (ATM) gene are associated with an increased risk of pancreatic ductal adenocarcinoma. It is important to identify germline ATM pathogenic variants in pancreatic cancer patients because these alterations are potentially targetable with chemotherapeutic drugs and/or radiation and have implications for other family members. As germline pathogenic variants in other genes have been associated with distinct histologic subtypes of pancreatic cancer, we studied the histomorphology of pancreatic cancer in 23 patients with germline ATM pathogenic variants. The histologic subtype was ductal adenocarcinoma in 19/23 (83%) of the patients, adenosquamous carcinoma in 1/23 (4%), and colloid (mucinous non-cystic) carcinoma in 3/23 (13%). The percentage of colloid (mucinous non-cystic) carcinomas is higher than we have previously observed in patients with familial and sporadic pancreatic cancer (1 and 2% in prior reports, p < 0.01 and p < 0.01, respectively). Three carcinomas (2 colloid carcinomas, 1 ductal adenocarcinoma) arose in association with intraductal papillary mucinous neoplasms. Among the resected pancreata, non-invasive precursor lesions, including pancreatic intraepithelial neoplasia and incipient intraductal papillary mucinous neoplasms, were identified in 83%. We conclude that pancreatic cancers in patients with germline ATM pathogenic variants are more frequently of colloid (mucinous non-cystic) morphology but are overall morphologically diverse supporting the utility of universal germline genetic testing for patients with pancreatic cancer.

Older breast cancer survivors may harbor hereditary cancer predisposition pathogenic variants and are at risk for clonal hematopoiesis

ObjectiveOur goal was to identify pathogenic variants (PV) associated with germline cancer predisposition in an unselected cohort of older breast cancer survivors. Older patients with cancer may also be at higher risk for clonal hematopoiesis (CH) due to their age and chemotherapy exposure. Therefore, we also explored the prevalence of PVs suggestive of CH. MethodsWe evaluated 44 older adults (65 years or older) diagnosed with breast cancer who survived at least two years after diagnosis from a prospective study, compared to healthy controls over the age of 65 (n = 36). DNA extracted from blood samples and a multi-gene panel test was used to evaluate for common hereditary cancer predisposition and CH PVs. Fisher's exact test was used to compare PV rates between groups. ResultsEight PVs in ATM, BRCA2 (x2), PALB2, RAD51D, BRIP1, and MUTYH (x2) were identified in 7 of 44 individuals with breast cancer (15.9%, 95% CI: 7–30%), whereas none were identified in healthy controls (p = .01). Results remained statistically significant after removal of MUTYH carriers (p = .045). PVs indicative of CH (ATM, NBN, and PPM1D [x2]) were identified in three of 27 individuals with breast cancer who received chemotherapy and in one healthy control. ConclusionModerate-risk and later disease onset high-risk hereditary cancer predisposition PVs were statistically significantly enriched in our survivorship cohort compared to controls. Because age- and chemotherapy-related CH are more frequent in this population, care must be taken to differentiate potential CH PVs from germline cancer predisposition PVs.

Unselected germline screening in pancreatic adenocarcinoma yields high rates of pathogenic and likely pathogenic variants (PV) in hereditary cancer susceptibility genes.

1582 Background: Recent literature cites a germline mutation rate of 3.9-15.1% in patients diagnosed with pancreatic ductal adenocarcinoma (PDAC) depending on breadth of genes tested, pre-selection of high-risk history and population substructure. True incidence of germline mutations in PDAC is unknown in unselected population. Methods: All patients (pts) diagnosed with PDAC in the province of British Columbia, Canada and referred to the Hereditary Cancer Program, were eligible to undergo 30 gene Color saliva kit testing under a research protocol, or clinical multigene testing if they met existing local criteria regardless of whether they signed on to the protocol. Any healthcare provider or patients themselves could refer. Results: 243 pts were referred between August 2016 and October 2018 but 25.1% (61) declined and 9.1% (22) died before testing. Of the 141 pts who consented to research protocol and completed germline testing, median age was 64 (46.1-81.0), 68.8% were European, 1.4% Ashkenazi Jewish heritage, 42% male, 61% non-smoker, 24.1% had personal history of a second cancer and 39% had metastatic disease. Baseline characteristics were similar between the PV positive and uninformative group. 20/25 PV were in known PDAC susceptibility genes with cascade screening implications (ATM (9), BRCA2 (4), BRCA2/ATM (1), CDKN2A (4), and MSH2 (2)). Excluding the 3 PV identified through carrier testing (1) and prior research identification (2), the rate of PV in unselected, unrelated PDAC cohort is 22/138 (15.9%). Utilizing previous NCCN criteria for BRCA1/BRCA2 testing or for familial pancreatic cancer did not appear to select for patients with higher risk of PV positive (12/65 (18.4%) PV positive rate versus 13/76 (17.1%) in those that didn’t meet criteria). Previous criteria would have missed 52% (13/25) PV in ATM (6), BRCA2/ATM (1), BRCA2 (2), MSH2 (2), NBN (1), CHEK2 (1). To date, a third of families with PV identified have accessed cascade testing in 38 relatives. Conclusions: Given the high incidence of 15.9% PV in hereditary cancer susceptibility genes, our data support recommendations for universal germline genetic testing of PDAC pts.

Germline mutation profile among Hispanic women with epithelial ovarian cancer (EOC).

1584 Background: Hospital-based studies have reported a 15% prevalence of BRCA1/ BRCA2( BRCA) mutations, with a slightly higher yield of other predisposition genes on multigene panel testing (MGPT) among women with EOC, and National Comprehensive Cancer Network guidelines recommend genetic cancer risk assessment for women with EOC. However, there is limited data about the genetic epidemiology of EOC among underrepresented populations, such as Hispanics. Consequently, we determined the germline mutation profile of Hispanics with EOC, and compared them with non-Hispanics. Methods: We included all women with a personal history of EOC from the U.S. and Latin America (LatAm; Mexico, Colombia, and Peru), enrolled in the Clinical Cancer Genomics Community Research Network registry. We assessed the prevalence of pathogenic variants (PV) in BRCA1/ BRCA2( BRCA) and other genes, contrasting the germline mutation profile between Hispanics living in LatAm, U.S. Hispanics, women of Ashkenazi Jewish (AJ) ancestry in the US, and other U.S. non-Hispanics. Results: Among 1186 women with EOC (209 from LatAm, 254 U.S. Hispanics l, 78 AJ, and 645 other non-Hispanic), 262 (22%) had a PV in BRCAgenes. Hispanics from LatAm and the U.S. had a similar frequency of BRCAmutations to AJ (30.6%, 29.9%, and 38.4%, respectively; p = 0.14); while non-Hispanics showed a significantly lower frequency of BRCAmutations (14.2%, p = 0.03). The most frequently mutated gene was BRCA1(n = 197, 74.6%), followed by BRCA2(n = 67, 25.3%). Among BRCA-negative cases (n = 924), 59% (n = 545) were evaluated by MGPT and PVs were identified in 2.9% [6 Hispanics (1.2%), 3 AJ (3.8%) and 26 Non-Hispanics (4%)]), of which 66% (n = 23) were in mismatch repair genes ( MSH2, MLH1, MSH6, PMS2), and 34% (n = 12) in other EOC-associated genes ( BRIP1, NBN, PALB2, RAD51C, and RAD51D). Clinically actionable PVs in ATM (n = 4; 0.3% ) and CHEK2 (n = 6; 0.5% ) were also observed. Conclusions: Hispanics with EOC have an elevated frequency of PV, similar to that of classic founder populations such as AJ, and significantly higher than other non-Hispanics. This is partially explained by a high prevalence of recurrent LatAm-specific PV, highlighting the importance of conducting genetic studies in underrepresented populations. There was modest incremental benefit of MGPT.