Pathogenic germline variants in patients with endometrial cancer of diverse ancestry

BACKGROUND

Racial disparities in outcomes exist in endometrial cancer (EC). The contribution of ancestry-based variations in germline pathogenic variants (gPVs) is unknown.

METHODS

Germline assessment of ≥76 cancer predisposition genes was performed in patients with EC undergoing tumor-normal Memorial Sloan Kettering Cancer Center Integrated Mutation Profiling of Actionable Cancer Targets sequencing from January 1, 2015 through June 30, 2021. Self-reported race/ethnicity and Ashkenazi Jewish ancestry data classified patients into groups. Genetic ancestry was inferred from Memorial Sloan Kettering Cancer Center Integrated Mutation Profiling of Actionable Cancer Targets. Rates of gPV and genetic counseling were compared by ancestry.

RESULTS

Among 1625 patients with EC, 216 (13%) had gPVs; 15 had >1 gPV. Rates of gPV varied by self-reported ancestry (Ashkenazi Jewish, 40/202 [20%]; Asian, 15/124 [12%]; Black/African American (AA), 12/171 [7.0%]; Hispanic, 15/124 [12%]; non-Hispanic (NH) White, 129/927 [14%]; missing, 5/77 [6.5%]; p = .009], with similar findings by genetic ancestry (p < .001). We observed a lower likelihood of gPVs in patients of Black/AA (odds ratio [OR], 0.44; 95% CI, 0.22-0.81) and African (AFR) ancestry (OR, 0.42; 95% CI, 0.18-0.85) and a higher likelihood in patients of Ashkenazi Jewish genetic ancestry (OR, 1.62; 95% CI; 1.11-2.34) compared with patients of non-Hispanic White/European ancestry, even after adjustment for age and molecular subtype. Somatic landscape influenced gPVs with lower rates of microsatellite instability-high tumors in patients of Black/AA and AFR ancestry. Among those with newly identified gPVs (n = 114), 102 (89%) were seen for genetic counseling, with lowest rates among Black/AA (75%) and AFR patients (67%).

CONCLUSIONS

In those with EC, gPV and genetic counseling varied by ancestry, with lowest rates among Black/AA and AFR patients, potentially contributing to disparities in outcomes given implications for treatment and cancer prevention.

PLAIN LANGUAGE SUMMARY

Black women with endometrial cancer do worse than White women, and there are many reasons for this disparity. Certain genetic changes from birth (mutations) can increase the risk of cancer, and it is unknown if rates of these changes are different between different ancestry groups. Genetic mutations in 1625 diverse women with endometrial cancer were studied and the lowest rates of mutations and genetic counseling were found in Black and African ancestry women. This could affect their treatment options as well as their families and may make disparities worse.

Pathogenic germline variants in non-BRCA1/2 homologous recombination genes in ovarian cancer: Analysis of tumor phenotype and survival

OBJECTIVE

To define molecular features of ovarian cancer (OC) with germline pathogenic variants (PVs) in non-BRCA homologous recombination (HR) genes and analyze survival compared to BRCA1/2 and wildtype (WT) OC.

METHODS

We included patients with OC undergoing tumor-normal sequencing (MSK-IMPACT) from 07/01/2015-12/31/2020, including germline assessment of BRCA1/2 and other HR genes ATM, BARD1, BRIP1, FANCA, FANCC, NBN, PALB2, RAD50, RAD51B, RAD51C, and RAD51D. Biallelic inactivation was assessed within tumors. Progression-free (PFS) and overall survival (OS) were calculated from pathologic diagnosis using the Kaplan-Meier method with left truncation. Whole-exome sequencing (WES) was performed in a subset.

RESULTS

Of 882 patients with OC, 56 (6.3%) had germline PVs in non-BRCA HR genes; 95 (11%) had BRCA1-associated OC (58 germline, 37 somatic); and 59 (6.7%) had BRCA2-associated OC (40 germline, 19 somatic). High rates of biallelic alterations were observed among germline PVs in BRIP1 (11/13), PALB2 (3/4), RAD51B (3/4), RAD51C (3/4), and RAD51D (8/10). In cases with WES (27/35), there was higher tumor mutational burden (TMB; median 2.5 [1.1-6.0] vs. 1.2 mut/Mb [0.6-2.6]) and enrichment of HR-deficient (HRD) mutational signatures in tumors associated with germline PALB2 and RAD51B/C/D compared with BRIP1 PVs (p < 0.01). Other features of HRD, including telomeric-allelic imbalance (TAI) and large-scale state transitions (LSTs), were similar. Although there was heterogeneity in PFS/OS by gene group, only BRCA1/2-associated OC had improved survival compared to WT OC (p < 0.01).

CONCLUSIONS

OCs associated with germline PVs in non-BRCA HR genes represent a heterogenous group, with PALB2 and RAD51B/C/D associated with an HRD phenotype.

Factors associated with detection of hereditary diffuse gastric cancer on endoscopy in individuals with germline CDH1 mutations

BACKGROUND AND AIMS

Individuals with germline pathogenic CDH1 variants have a high risk of hereditary diffuse gastric cancer. The sensitivity of EGD in detecting signet ring cell carcinoma (SRCC) in this population is low. We aimed to identify endoscopic findings and biopsy practices associated with detection of SRCC.

METHODS

This retrospective cohort included individuals with a germline pathogenic/likely pathogenic CDH1 variant undergoing at least 1 EGD at Memorial Sloan Kettering Cancer Center between January 1, 2006, and March 25, 2022. The primary outcome was detection of SRCC on EGD. Findings on gastrectomy were also assessed. The study included periods before and after implementation of the Cambridge protocol for endoscopic surveillance, allowing for assessment of a spectrum of biopsy practices.

RESULTS

Ninety-eight CDH1 patients underwent at least 1 EGD at our institution. SRCC was detected in 20 (20%) individuals on EGD overall and in 50 (86%) of the 58 patients undergoing gastrectomy. Most SRCC foci were detected in the gastric cardia/fundus (EGD, 50%; gastrectomy, 62%) and body/transition zone (EGD, 60%; gastrectomy, 62%). Biopsy results of gastric pale mucosal areas were associated with detection of SRCC (P < .01). The total number of biopsy samples taken on EGD was associated with increased detection of SRCC (P = .01), with 43% detected when ≥40 samples were taken.

CONCLUSIONS

Targeted biopsy sampling of gastric pale mucosal areas and increasing number of biopsy samples taken on EGD were associated with detection of SRCC. SRCC foci were mostly detected in the proximal stomach, supporting updated endoscopic surveillance guidelines. Further studies are needed to refine endoscopic protocols to improve SRCC detection in this high-risk population.

Germline drivers of gynecologic carcinosarcomas

OBJECTIVES

To describe the prevalence of germline pathogenic variants (gPVs) in endometrial and ovarian carcinosarcomas and determine if gPVs are drivers of carcinosarcoma.

METHODS

Patients with endometrial or ovarian carcinosarcomas who underwent clinical tumor-normal sequencing from 1/1/2015 to 6/1/2021 and consented to germline assessment of ≥76 cancer predisposition genes were included. In patients with gPVs, biallelic inactivation was identified through analysis of loss of heterozygosity and somatic pathogenic alterations.

RESULTS

Of 216 patients identified, 167 (77%) were diagnosed with endometrial carcinosarcoma and 49 (23%) with ovarian carcinosarcoma. Overall, 33 gPVs were observed in 29 patients (13%); 20 gPVs (61%) had biallelic loss in tumors. The rate of high-penetrance gPVs overall was 7% (16 of 216); 88% of high-penetrance gPVs had biallelic loss. In the endometrial carcinosarcoma cohort, 22 gPVs were found in 19 (11%) of 167 patients; 12 gPVs (55%) had biallelic loss in tumors, including 8 (89%) of 9 in high-penetrance gPVs. Among the ovarian carcinosarcoma cohort, 11 gPVs were found in 10 (20%) of 49 patients; 8 gPVs (73%) had biallelic loss in tumors, and all evaluable high-penetrance gPVs (n = 6) had biallelic loss. All gPVs in homologous recombination (BRCA1, BRCA2, RAD51C) and Lynch syndrome (MSH2, MSH6) genes had biallelic loss in tumors (n = 15).

CONCLUSIONS

gPVs in genes affecting homologous recombination- or Lynch-associated mismatch repair exhibited biallelic inactivation within tumors, suggesting likely drivers of gynecologic carcinosarcoma. Our data support germline testing for patients with gynecologic carcinosarcomas, given implications for treatment and risk-reduction in patients and at-risk family members.

Comprehensive analysis of germline drivers in endometrial cancer

BACKGROUND

We sought to determine the prevalence of germline pathogenic variants (gPVs) in unselected patients with endometrial cancer (EC), define biallelic gPVs within tumors, and describe their associations with clinicopathologic features.

METHODS

Germline assessment of at least 76 cancer predisposition genes was performed in patients with EC undergoing clinical tumor-normal Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT) sequencing from January 1, 2015, to June 30, 2021. In patients with gPVs, biallelic alterations in ECs were identified through analysis of loss of heterozygosity and somatic PVs. Clinicopathologic variables were compared using nonparametric tests.

RESULTS

Of 1625 patients with EC, 216 (13%) had gPVs, and 15 patients had 2 gPVs. There were 231 gPVs in 35 genes (75 [32%] high penetrance; 39 [17%] moderate penetrance; and 117 [51%] low, recessive, or uncertain penetrance). Compared with those without gPVs, patients with gPVs were younger (P = .002), more often White (P = .009), and less obese (P = .025) and had differences in distribution of tumor histology (P = .017) and molecular subtype (P < .001). Among 231 gPVs, 74 (32%) exhibited biallelic inactivation within tumors. For high-penetrance gPVs, 63% (47 of 75) of ECs had biallelic alterations, primarily affecting mismatch repair (MMR) and homologous recombination related genes, including BRCA1,BRCA2, RAD51D, and PALB2. Biallelic inactivation varied across molecular subtypes with highest rates in microsatellite instability-high (MSI-H) or copy-number (CN)-high subtypes (3 of 12 [25%] POLE, 30 of 77 [39%] MSI-H, 27 of 60 [45%] CN-high, 9 of 57 [16%] CN-low; P < .001).

CONCLUSIONS

Of unselected patients with EC, 13% had gPVs, with 63% of gPVs in high-penetrance genes (MMR and homologous recombination) exhibiting biallelic inactivation, potentially driving cancer development. This supports germline assessment in EC given implications for treatment and cancer prevention.

Prevalence and Clinical Implications of Mismatch Repair-Proficient Colorectal Cancer in Patients With Lynch Syndrome

PURPOSE

Lynch syndrome (LS)-associated colorectal cancer (CRC) is characterized by mismatch repair-deficiency (MMR-D) and/or microsatellite instability (MSI). However, with increasing utilization of germline testing, MMR-proficient (MMR-P) and/or microsatellite stable (MSS) CRC has also been observed. We sought to characterize MMR-P/MSS CRC among patients with LS.

METHODS

Patients with solid tumors with germline MMR pathogenic/likely pathogenic (P/LP) variants were identified on a prospective matched tumor-normal next-generation sequencing (NGS) protocol. CRCs were evaluated for MMR-D via immunohistochemical (IHC) staining and/or MSI via NGS. Clinical variables were correlated with MMR status using nonparametric tests.

RESULTS

Among 17,617 patients with solid tumors, 1.4% (n = 242) had LS. A total of 36% (86 of 242) of patients with LS had at least one CRC that underwent NGS profiling, amounting to 99 pooled CRCs assessed. A total of 10% (10 of 99) of CRCs were MMR-P, with 100% concordance between MSS status and retained MMR protein staining. A total of 89% (8 of 9) of patients in the MMR-P group had MSH6 or PMS2 variants, compared with 30% (23 of 77) in the MMR-D group (P = .001). A total of 46% (6 of 13) of PMS2+ patients had MMR-P CRC. The median age of onset was 58 and 43 years for MMR-P and MMR-D CRC, respectively (P = .07). Despite the later median age of onset, 40% (4 of 10) of MMR-P CRCs were diagnosed <50. A total of 60% (6 of 10) of MMR-P CRCs were metastatic compared with 13% (12 of 89) of MMR-D CRCs (P = .002). A total of 33% (3 of 9) of patients with MMR-P CRC did not meet LS testing criteria.

CONCLUSION

Patients with LS remained at risk for MMR-P CRC, which was more prevalent among patients with MSH6 and PMS2 variants. MMR-P CRC was later onset and more commonly metastatic compared with MMR-D CRC. Confirmation of tumor MMR/MSI status is critical for patient management and familial risk estimation.

Diagnostic yield and clinical relevance of expanded genetic testing for cancer patients

BACKGROUND

Genetic testing (GT) for hereditary cancer predisposition is traditionally performed on selected genes based on established guidelines for each cancer type. Recently, expanded GT (eGT) using large hereditary cancer gene panels uncovered hereditary predisposition in a greater proportion of patients than previously anticipated. We sought to define the diagnostic yield of eGT and its clinical relevance in a broad cancer patient population over a 5-year period.

METHODS

A total of 17,523 cancer patients with a broad range of solid tumors, who received eGT at Memorial Sloan Kettering Cancer Center between July 2015 to April 2020, were included in the study. The patients were unselected for current GT criteria such as cancer type, age of onset, and/or family history of disease. The diagnostic yield of eGT was determined for each cancer type. For 9187 patients with five common cancer types frequently interrogated for hereditary predisposition (breast, colorectal, ovarian, pancreatic, and prostate cancer), the rate of pathogenic/likely pathogenic (P/LP) variants in genes that have been associated with each cancer type was analyzed. The clinical implications of additional findings in genes not known to be associated with a patients' cancer type were investigated.

RESULTS

16.7% of patients in a broad cancer cohort had P/LP variants in hereditary cancer predisposition genes identified by eGT. The diagnostic yield of eGT in patients with breast, colorectal, ovarian, pancreatic, and prostate cancer was 17.5%, 15.3%, 24.2%, 19.4%, and 15.9%, respectively. Additionally, 8% of the patients with five common cancers had P/LP variants in genes not known to be associated with the patient's current cancer type, with 0.8% of them having such a variant that confers a high risk for another cancer type. Analysis of clinical and family histories revealed that 74% of patients with variants in genes not associated with their current cancer type but which conferred a high risk for another cancer did not meet the current GT criteria for the genes harboring these variants. One or more variants of uncertain significance were identified in 57% of the patients.

CONCLUSIONS

Compared to targeted testing approaches, eGT can increase the yield of detection of hereditary cancer predisposition in patients with a range of tumors, allowing opportunities for enhanced surveillance and intervention. The benefits of performing eGT should be weighed against the added number of VUSs identified with this approach.

Early age of onset and broad cancer spectrum persist in MSH6- and PMS2-associated Lynch syndrome

PURPOSE

This study aimed to characterize MSH6/PMS2-associated mismatch repair-deficient (MMR-D)/microsatellite instability-high (MSI-H) tumors, given revised guidelines suggesting more modest phenotypes.

METHODS

Patients who consented to Institutional Review Board-approved protocols of tumor/germline sequencing or Lynch syndrome registry at a single institution from February 2005 to January 2021 with germline, heterozygous MSH6/PMS2 pathogenic/likely pathogenic variants were identified. Clinical data were abstracted and correlated with MMR/microsatellite instability status using nonparametric tests.

RESULTS

We identified 243 patients (133 sequencing, 110 registry) with germline MSH6/PMS2 pathogenic/likely pathogenic variants; 186 (77%) had >1 cancer. Of 261 pooled tumors, colorectal cancer (CRC) and endometrial cancer (EC) comprised 55% and 43% of cancers in MSH6 and PMS2, respectively; 192 tumors underwent molecular assessments and 122 (64%) were MMR-D/MSI-H (77 in MSH6, 45 in PMS2). MMR-D/MSI-H cancers included CRC (n = 56), EC (n = 35), small bowel cancer (n = 6), ovarian cancer (n = 6), urothelial cancer (n = 5), pancreas/biliary cancer (n = 4), gastric/esophageal cancer (n = 3), nonmelanoma skin tumors (n = 3), prostate cancer (n = 2), breast cancer (n = 1), and central nervous system/brain cancer (n = 1). Among MMR-D/MSI-H CRC and EC, median age of diagnosis was 51.5 (range = 27-80) and 55 (range = 39-74) years, respectively; 9 of 56 (16%) MMR-D/MSI-H CRCs were diagnosed at age <35 years.

CONCLUSION

MSH6/PMS2 heterozygotes remain at risk for a broad spectrum of cancers, with 16% of MMR-D/MSI-H CRCs presenting before upper threshold of initiation of colonoscopy per guidelines.

A Comprehensive Comparison of Early-Onset and Average-Onset Colorectal Cancers

BACKGROUND

The causative factors for the recent increase in early-onset colorectal cancer (EO-CRC) incidence are unknown. We sought to determine if early-onset disease is clinically or genomically distinct from average-onset colorectal cancer (AO-CRC).

METHODS

Clinical, histopathologic, and genomic characteristics of EO-CRC patients (2014-2019), divided into age 35 years and younger and 36-49 years at diagnosis, were compared with AO-CRC (50 years and older). Patients with mismatch repair deficient tumors, CRC-related hereditary syndromes, and inflammatory bowel disease were excluded from all but the germline analysis. All statistical tests were 2-sided.

RESULTS

In total, 759 patients with EO-CRC (35 years, n = 151; 36-49 years, n = 608) and AO-CRC (n = 687) were included. Left-sided tumors (35 years and younger = 80.8%; 36-49 years = 83.7%; AO = 63.9%; P < .001 for both comparisons), rectal bleeding (35 years and younger = 41.1%; 36-49 years = 41.0%; AO = 25.9%; P = .001 and P < .001, respectively), and abdominal pain (35 years and younger = 37.1%; 36-49 years = 34.0%; AO = 26.8%; P = .01 and P = .005, respectively) were more common in EO-CRC. Among microsatellite stable tumors, we found no differences in histopathologic tumor characteristics. Initially, differences in TP53 and Receptor Tyrosine Kinase signaling pathway (RTK-RAS)alterations were noted by age. However, on multivariate analysis including somatic gene analysis and tumor sidedness, no statistically significant differences at the gene or pathway level were demonstrated. Among advanced microsatellite stable CRCs, chemotherapy response and survival were equivalent by age cohorts. Pathogenic germline variants were identified in 23.3% of patients 35 years and younger vs 14.1% of AO-CRC (P = .01).

CONCLUSIONS

EO-CRCs are more commonly left-sided and present with rectal bleeding and abdominal pain but are otherwise clinically and genomically indistinguishable from AO-CRCs. Aggressive treatment regimens based solely on the age at CRC diagnosis are not warranted.

Multiple Primary Cancers in Patients Undergoing Tumor-Normal Sequencing Define Novel Associations

BACKGROUND

Cancer survivors are developing more subsequent tumors. We sought to characterize patients with multiple (≥2) primary cancers (MPC) to assess associations and genetic mechanisms.

METHODS

Patients were prospectively consented (01/2013-02/2019) to tumor-normal sequencing via a custom targeted panel (MSK-IMPACT). A subset consented to return of results of ≥76 cancer predisposition genes. International Agency for Research on Cancer (IARC) 2004 rules for defining MPC were applied. Tumor pairs were created to assess relationships between cancers. Age-adjusted, sex-specific, standardized incidence ratios (SIR) for first to second cancer event combinations were calculated using SEER rates, adjusting for confounders and time of ascertainment. Associations were made with germline and somatic variants.

RESULTS

Of 24,241 patients, 4,340 had MPC (18%); 20% were synchronous. Most (80%) had two primaries; however, 4% had ≥4 cancers. SIR analysis found lymphoma-lung, lymphoma-uterine, breast-brain, and melanoma-lung pairs in women and prostate-mesothelioma, prostate-sarcoma, melanoma-stomach, and prostate-brain pairs in men in excess of expected after accounting for synchronous tumors, known inherited cancer syndromes, and environmental exposures. Of 1,580 (36%) patients who received germline results, 324 (21%) had 361 pathogenic/likely pathogenic variants (PV), 159 (44%) in high penetrance genes. Of tumor samples analyzed, 55% exhibited loss of heterozygosity at the germline variant. In those with negative germline findings, melanoma, prostate, and breast cancers were common.

CONCLUSIONS

We identified tumor pairs without known predisposing mutations that merit confirmation and will require novel strategies to elucidate genetic mechanisms of shared susceptibilities.

IMPACT

If verified, patients with MPC with novel phenotypes may benefit from targeted cancer surveillance.

Early-Onset Pancreas Cancer: Clinical Descriptors, Genomics, and Outcomes

BACKGROUND

Recent evidence suggests a rising incidence of cancer in younger individuals. Herein, we report the epidemiologic, pathologic, and molecular characteristics of a patient cohort with early-onset pancreas cancer (EOPC).

METHODS

Institutional databases were queried for demographics, treatment history, genomic results, and outcomes. Overall survival from date of diagnosis was estimated using Kaplan-Meier method.

RESULTS

Between 2008 and 2018, 450 patients with EOPC were identified at Memorial Sloan Kettering. Median overall survival was 16.3  (95% confidence interval [CI] = 14.6 to 17.7) months in the entire cohort and 11.3  (95% CI = 10.2 to 12.2) months for patients with stage IV disease at diagnosis. Of the patients, 132 (29.3% of the cohort) underwent somatic testing; 21 of 132 (15.9%) had RAS wild-type cancers with identification of several actionable alterations, including ETV6-NTRK3, TPR-NTRK1, SCLA5-NRG1, and ATP1B1-NRG1 fusions, IDH1 R132C mutation, and mismatch repair deficiency. A total of 138 patients (30.7% of the cohort) underwent germline testing; 44 of 138 (31.9%) had a pathogenic germline variant (PGV), and 27.5% harbored alterations in cancer susceptibility genes. Of patients seen between 2015 and 2018, 30 of 193 (15.5%) had a PGV. Among 138 who underwent germline testing, those with a PGV had a reduced all-cause mortality compared with patients without a PGV controlling for stage and year of diagnosis (hazard ratio = 0.42, 95% CI = 0.26 to 0.69).

CONCLUSIONS

PGVs are present in a substantial minority of patients with EOPC. Actionable somatic alterations were identified frequently in EOPC, enriched in the RAS wild-type subgroup. These observations underpin the recent guidelines for universal germline testing and somatic profiling in pancreatic ductal adenocarcinoma.

Therapeutic Implications of Germline Testing in Patients With Advanced Cancers

PURPOSE

Tumor mutational profiling is increasingly performed in patients with advanced cancer. We determined the extent to which germline mutation profiling guides therapy selection in patients with advanced cancer.

METHODS

Patients with cancer undergoing tumor genomic profiling were prospectively consented for germline cancer predisposition gene analysis (2015-2019). In patients harboring germline likely pathogenic or pathogenic (LP/P) alterations, therapeutic actionability was classified using a precision oncology knowledge base. Patients with metastatic or recurrent cancer receiving germline genotype-directed therapy were determined.

RESULTS

Among 11,947 patients across > 50 malignancies, 17% (n = 2,037) harbored a germline LP/P variant. By oncology knowledge base classification, 9% (n = 1042) had an LP/P variant in a gene with therapeutic implications (4% level 1; 4% level 3B; < 1% level 4). BRCA1/2 variants accounted for 42% of therapeutically actionable findings, followed by CHEK2 (13%), ATM (12%), mismatch repair genes (11%), and PALB2 (5%). When limited to the 9,079 patients with metastatic or recurrent cancer, 8% (n = 710) harbored level 1 or 3B genetic findings and 3.2% (n = 289) received germline genotype-directed therapy. Germline genotype-directed therapy was received by 61% and 18% of metastatic cancer patients with level 1 and level 3B findings, respectively, and by 54% of BRCA1/2, 75% of mismatch repair, 43% of PALB2, 35% of RAD51C/D, 24% of BRIP1, and 19% of ATM carriers. Of BRCA1/2 patients receiving a poly(ADP-ribose) polymerase inhibitor, 45% (84 of 188) had tumors other than breast or ovarian cancer, wherein the drug, at time of delivery, was delivered in an investigational setting.

CONCLUSION

In a pan-cancer analysis, 8% of patients with advanced cancer harbored a germline variant with therapeutic actionability with 40% of these patients receiving germline genotype-directed treatment. Germline sequence analysis is additive to tumor sequence analysis for therapy selection and should be considered for all patients with advanced cancer.

Paired Tumor-Normal Sequencing Provides Insights Into the TP53-Related Cancer Spectrum in Patients With Li-Fraumeni Syndrome

BACKGROUND

Genetic testing for Li-Fraumeni syndrome (LFS) is performed by using blood specimens from patients selected based on phenotype-dependent guidelines. This approach is problematic for understanding the LFS clinical spectrum because patients with nonclassical presentations are missed, clonal hematopoiesis-related somatic blood alterations cannot be distinguished from germline variants, and unrelated tumors cannot be differentiated from those driven by germline TP53 defects.

METHODS

To provide insights into the LFS-related cancer spectrum, we analyzed paired tumor-blood DNA sequencing results in 17 922 patients with cancer and distinguished clonal hematopoiesis-related, mosaic, and germline TP53 variants. Loss of heterozygosity and TP53 mutational status were assessed in tumors, followed by immunohistochemistry for p53 expression on a subset to identify those lacking biallelic TP53 inactivation.

RESULTS

Pathogenic/likely pathogenic TP53 variants were identified in 50 patients, 12 (24.0%) of which were clonal hematopoiesis related and 4 (8.0%) of which were mosaic. Twelve (35.3%) of 34 patients with germline TP53 variants did not meet LFS testing criteria. Loss of heterozygosity of germline TP53 variant was observed in 96.0% (95% confidence interval [CI] = 79.7% to 99.9%) of core LFS spectrum-type tumors vs 45.5% (95% CI = 16.8% to 76.6%) of other tumors and 91.3% (95% CI = 72.0% to 98.9%) of tumors from patients who met LFS testing criteria vs 61.5% (95% CI = 31.6% to 86.1%) of tumors from patients who did not. Tumors retaining the wild-type TP53 allele exhibited wild-type p53 expression.

CONCLUSIONS

Our results indicate that some TP53 variants identified in blood-only sequencing are not germline and a substantial proportion of patients with LFS are missed based on current testing guidelines. Additionally, a subset of tumors from patients with LFS do not have biallelic TP53 inactivation and may represent cancers unrelated to their germline TP53 defect.

Abstract PO-034: A collaborative approach to increase germline testing and counseling uptake within New York City’s underserved patient population

Background: Understanding the role of genetic drivers in cancer is a fundamental component of precision medicine. Further, identification of germline mutations provides important clinical data for patients. Understanding the risk conferred by inheriting certain mutations can guide treatment and screening behaviors for both patients and their family members. Despite the importance of testing, minority patients are less likely to undergo germline testing. Patient and physician reported barriers include limited or no knowledge of genetic tests, limited knowledge of hereditary cancer syndromes, lack of educational materials, time constraints, lack of genetic counselors, and out-of-pocket costs. Objective: To describe how an academic-community collaboration between local healthcare institutions addresses some known barriers to germline testing and counseling in a typically underrepresented patient population. Methods: The Cancer Health Equity Research Program (CHERP) at Memorial Sloan Kettering (MSK) partners with local community hospitals, which serve diverse populations, to provide somatic and germline testing to their cancer patients under the research protocol, MSK-IMPACT™ (Integrated Mutation Profiling of Actionable Cancer Targets). Testing and counseling are provided by the Center for Molecular Oncology and Clinical Genetics Service at MSK. Site clinicians are trained on study procedures to ensure they are prepared to educate their patients on the purpose of genetic testing. Non-clinical MSK research staff (NCMRS) are trained as consenting professionals and delegated to a site to address clinic time constraints. NCMRS facilitate the collection, shipment, and tracking of biospecimens and collaborate with MSK’s Clinical Genetics Service on behalf of the sites. To address both educational and language barriers, a subtitled video on germline testing, translated informed consents, and translated educational brochures are provided to each site. Results: Since March 2018, 270 patients from our CHERP sites agreed to germline testing. Self-reported race is as follows: 35 Asian (13.0%), 123 Black (45.6%), 25 Caucasian (9.3%), 1 Pacific Islander (0.4%), 11 Other (4.1%), and 75 Unknown (27.8%). Additionally, 99 (36.7%) patients identified as Hispanic and Hispanics represent 90.7% of self-reported Unknown race and 100% of the self-reported Other race. Of the 270 patients, 201 have had successful germline testing (62 patients ineligible and 7 pending results) with 26 (12.9%) having a positive finding. Genetic counseling was provided for 17 (65.4%) of these patients, with 6 sessions in-person and 11 telegenetic sessions. Conclusion: Disparities in genetic testing are well documented and efforts to expand access to testing and counseling for minority patients are urgently needed. In partnership with local hospitals, CHERP addresses many of the barriers that contribute to these disparities and demonstrated success in providing germline testing and counseling for minority patients.

Citation Format: Kenya P. Vado, Thomas Reynolds, Kellie Jack, Linda Bulone, Margaret Kemeny, Jason Gonsky, Lewis Kampel, Shadai Mcmillan, Anna Maio, Margaret Sheehan, Erin Salo-Mullen, Sandy Naupari, Jesse Galle, Alisha Williams, Zsofia Stadler, Mark Robson, David Solit, Paul Sabbatini, Carol Brown. A collaborative approach to increase germline testing and counseling uptake within New York City’s underserved patient population [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-034.

Insertion of an Alu-like element in MLH1 intron 7 as a novel cause of Lynch syndrome

Background

Lynch Syndrome (LS) is caused by germline mutations in the DNA mismatch repair (MMR) genes with mutations in MLH1 accounting for ~40% of LS‐related alterations.

Methods

MSK‐IMPACT analysis was performed on peripheral blood from a patient with early‐ onset colorectal cancer. Subsequently PCR and sequencing was performed to characterize the insertion. Immunohistochemistry for MMR genes and MLH1 promoter methylation were analyzed on patient's tumor.

Results

MSK‐IMPACT germline testing revealed an insertion into c.588+8_588+9 of MLH1 intron 7. The insertion was further characterized as an AluSx‐like element with ~115 bp in length. Functional studies demonstrated that the AluSx‐like element led to complete disruption of mRNA splicing and probably resulted in transcriptional termination at the poly (A) region of the AluSx‐like insertion.

Conclusions

The insertion of a truncated AluSx like element into MLH1 intron 7 results in aberrant splicing and transcription, thereby causing Lynch syndrome. This study confirms that retrotransposon insertions may be an important mechanism for cancer predisposition.

Abstract 1122: Germline mutation prevalence in young adults with cancer

The identification of germline pathogenic variants in young adult cancer patients is especially critical given risk of second primary cancers, need for appropriate long-term surveillance, potential reproductive implications, and cascade testing of at-risk family members. We sought to determine the prevalence of germline susceptibility in cancer patients, age 18-39, across diverse solid tumor phenotypes. A total of 1201 cases, diagnosed between ages 18-39 were prospectively ascertained from 2015-2019 under a human subjects-approved protocol that provided result transmission of germline analysis. A next-generation sequencing panel consisting of up to 88 genes previously implicated in cancer predisposition (MSK-IMPACT) was utilized. Based on SEER data, we refined our population of young cancer patients into those with 1) early-onset cancer (EO-CA), defined as cancer wherein age 39 is &gt;1 standard deviation (STD) below the mean age of diagnosis for that cancer type and 2) young-adult cancer (YA-CA), defined as cancer wherein age 39 is &lt;1 STD below the mean age at cancer diagnosis. Among EO-CA (n=877) cases, the most common cancers included colorectal, breast, kidney, pancreas, and ovarian cancer, while among YA-CAs (n=324), the most frequent diagnoses were sarcoma, brain, testicular and thyroid cancer. Germline prevalence of likely pathogenic or pathogenic variants (PV) was 21% in the EO-CA versus 13% in YA-CA patients (p=0.002), with an enrichment of high- and moderate-penetrance PVs in the EO-CA cohort (15% vs 10%; p=0.01). Among EO-CAs, the most commonly mutated genes were BRCA2, BRCA1, CHEK2 and ATM, with pancreas, breast, and kidney cancer harboring the highest rates of germline PVs. In contrast, in the YA-CA cohort, TP53 and SDHA mutations predominated. Among YA-CA patients with sarcoma, the 18.1% mutation prevalence was similar to the prevalence in EO-CAs. Matched tumor analyses assessing biallelic inactivation is on-going and will be presented. Among young adults with early-onset phenotypes of malignancies typically presenting at later ages, the increased prevalence of germline PVs supports a role for genetic testing irrespective of tumor type.

Citation Format: Zsofia K. Stadler, Anna Maio, Angelika Padunan, Yelena Kemel, Erin Salo-Mullen, Margaret Sheehan, Kimeisha Belanfanti, Prince R. Tejada, Ozge Birsoy, Diana Mandelker, Liying Zhang, Jesse Galle, Darren Feldman, Laura Boucai, Julia Glade Bender, Anna Piotrowski, Carol Aghajanian, Karen A. Cadoo, Maria I. Carlo, Michael Walsh, Yelena Janjigian, Eileen O'Reilly, Lisa M. DeAngelis, David B. Solit, Barry Taylor, Andrea Cercek, William Tap, Mark E. Robson, Michael F. Berger, Kenneth Offit, Luis A. Diaz. Germline mutation prevalence in young adults with cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1122.

Mismatch Repair-Deficient Rectal Cancer and Resistance to Neoadjuvant Chemotherapy

PURPOSE

Evaluate response of mismatch repair-deficient (dMMR) rectal cancer to neoadjuvant chemotherapy.

EXPERIMENTAL DESIGN

dMMR rectal tumors at Memorial Sloan Kettering Cancer Center (New York, NY) were retrospectively reviewed for characteristics, treatment, and outcomes. Fifty patients with dMMR rectal cancer were identified by IHC and/or microsatellite instability analysis, with initial treatment response compared with a matched MMR-proficient (pMMR) rectal cancer cohort. Germline and somatic mutation analyses were evaluated. Patient-derived dMMR rectal tumoroids were assessed for chemotherapy sensitivity.

RESULTS

Of 21 patients receiving neoadjuvant chemotherapy (fluorouracil/oxaliplatin), six (29%) had progression of disease. In comparison, no progression was noted in 63 pMMR rectal tumors (P = 0.0001). Rectal cancer dMMR tumoroids reflected this resistance to chemotherapy. No genomic predictors of chemotherapy response were identified. Of 16 patients receiving chemoradiation, 13 (93%) experienced tumor downstaging; one patient had stable disease, comparable with 48 pMMR rectal cancers. Of 13 patients undergoing surgery, 12 (92%) had early-stage disease. Forty-two (84%) of the 50 patients tested positive for Lynch syndrome with enrichment of germline MSH2 and MSH6 mutations when compared with 193 patients with Lynch syndrome-associated colon cancer (MSH2, 57% vs 36%; MSH6, 17% vs 9%; P < 0.003).

CONCLUSIONS

Over one-fourth of dMMR rectal tumors treated with neoadjuvant chemotherapy exhibited disease progression. Conversely, dMMR rectal tumors were sensitive to chemoradiation. MMR status should be performed upfront in all locally advanced rectal tumors with careful monitoring for response on neoadjuvant chemotherapy and genetic testing for Lynch syndrome in patients with dMMR rectal cancer.

A Multi-Institutional Cohort of Therapy-Associated Polyposis in Childhood and Young Adulthood Cancer Survivors

Prior small reports have postulated a link between gastrointestinal polyposis and childhood and young adulthood cancer (CYAC) treatment (therapy-associated polyposis; TAP), but this remains a poorly understood phenomenon. The aim of this study was to describe the phenotypic spectrum of TAP in a multi-institutional cohort. TAP cases were identified from eight high-risk cancer centers. Cases were defined as patients with ≥10 gastrointestinal polyps without known causative germline alteration or hereditary colorectal cancer predisposition syndrome who had a history of prior treatment with chemotherapy and/or radiotherapy for CYAC. A total of 34 TAP cases were included (original CYAC: 27 Hodgkin lymphoma, three neuroblastoma, one acute myeloid leukemia, one medulloblastoma, one nephroblastoma, and one non-Hodgkin lymphoma). Gastrointestinal polyposis was first detected at a median of 27 years (interquartile range, 20-33) after CYAC treatment. A total of 12 of 34 (35%) TAP cases had ≥50 colorectal polyps. A total of 32 of 34 (94%) had >1 histologic polyp type. A total of 25 of 34 (74%) had clinical features suggestive of ≥1 colorectal cancer predisposition syndrome [e.g., attenuated familial adenomatous polyposis (FAP), serrated polyposis syndrome, extracolonic manifestations of FAP, mismatch repair-deficient colorectal cancer, or hamartomatous polyposis] including 8 of 34 (24%) with features of multiple such syndromes. TAP is an apparently acquired phenomenon that should be considered in patients who develop significant polyposis without known causative germline alteration but who have had prior treatment for a CYAC. Patients with TAP have features that may mimic various hereditary colorectal cancer syndromes, suggesting multiple concurrent biologic mechanisms, and recognition of this diagnosis may have implications for cancer risk and screening.

Outcome of Pancreatic Cancer Surveillance Among High-Risk Individuals Tested for Germline Mutations in BRCA1 and BRCA2

Germline mutations in BRCA1/2 are risk factors for pancreatic ductal adenocarcinoma (PDAC). The aim of this study was to evaluate whether results of surveillance for PDAC in high risk individuals (HRI) differ between those with and without a pathogenic BRCA1/2 mutation. This prospective study was conducted within the Pancreatic Tumor Registry at a major cancer center. There were 83 HRIs with ≥1 first-degree relative with PDAC who underwent surveillance and testing for pathogenic germline mutations in BRCA1/2 A secondary analysis includes 18 HRIs with known mutations in BRCA1/2 but with weaker family history. HRIs were evaluated over time using magnetic resonance cholangiopancreatography (MRCP) and endoscopic ultrasound when indicated by MRCP findings. We reviewed imaging results, blinded to mutation status. Demographic information was obtained from interviewer-administered questionnaires. The outcome was the proportion with any pancreatic abnormality identified at initial or follow-up surveillance. Among the 83 HRIs in the main analysis, 48 had a mutation in BRCA1/2 and 35 did not. Overall, 16 of 48 (33%) BRCA1/2-positive and 13 of 35 (37%) BRCA1/2-negative participants had pancreatic abnormalities on imaging; in each group, all but one finding was an intraductal papillary mucinous neoplasm. Among those with pathogenic mutations but weaker family history, results were similar: 7 of 18 (39%) with pancreatic abnormalities. Results of surveillance for pancreatic abnormalities on imaging are similar regardless of BRCA1/2 mutation status. While the results from this small study need confirmation in other studies, at present there does not appear to be increased yield from targeting individuals with BRCA1/2 mutations for surveillance.

Prospective Evaluation of Germline Alterations in Patients With Exocrine Pancreatic Neoplasms

Background

Identification of pathogenic germline alterations (PGAs) has important clinical and therapeutic implications in pancreas cancer. We performed comprehensive germline testing (GT) in an unselected prospective cohort of patients with exocrine pancreatic neoplasms with genotype and phenotype association to facilitate identification of prognostic and/or predictive biomarkers and examine potential therapeutic implications.

Methods

Six hundred fifteen unselected patients with exocrine pancreatic neoplasms were prospectively consented for somatic tumor and matched sample profiling for 410-468 genes. GT for PGAs in 76 genes associated with cancer susceptibility was performed in an "identified" manner in 356 (57.9%) patients and in an "anonymized" manner in 259 (42.1%) patients, using an institutional review board-approved protocol. Detailed clinical and pathological features, response to platinum, and overall survival (OS) were collected for the identified cohort. OS was analyzed with Kaplan-Meier curves.

Results

PGAs were present in 122 (19.8%) of 615 patients involving 24 different genes, including BRCA1/2, ATM, PALB2, and multiple additional genes associated with the DNA damage response pathway. Of 122 patients with germline alterations, 41.8% did not meet current guidelines for GT. The difference in median OS was not statistically significant between patients with and without PGA (50.8 months, 95% confidence interval = 34.5 to not reached, two-sided P = .94). Loss of heterozygosity was found in 60.0% of BRCA1/2.

Conclusions

PGAs frequently occur in pancreas exocrine neoplasms and involve multiple genes beyond those previously associated with hereditary pancreatic cancer. These PGAs are therapeutically actionable in about 5% to 10% of patients. These data support routinely offering GT in all pancreatic ductal adenocarcimona patients with a broad panel of known hereditary cancer predisposition genes.

Evaluating Mismatch Repair Deficiency in Pancreatic Adenocarcinoma: Challenges and Recommendations

Purpose: Immune checkpoint inhibition has been shown to generate profound and durable responses in mismatch repair deficient (MMR-D) solid tumors and has elicited interest in detection tools and strategies to guide therapeutic decision-making. Herein we address questions on the appropriate screening, detection methods, patient selection, and initiation of therapy for MMR-D pancreatic ductal adenocarcinoma (PDAC) and assess the utility of next-generation sequencing (NGS) in providing additional prognostic and predictive information for MMR-D PDAC.Experimental Design: Archival and prospectively acquired samples and matched normal DNA from N = 833 PDAC cases were analyzed using a hybridization capture-based, NGS assay designed to perform targeted deep sequencing of all exons and selected introns of 341 to 468 cancer-associated genes. A computational program using NGS data derived the MSI status from the tumor-normal paired genome sequencing data. Available germline testing, IHC, and microsatellite instability (MSI) PCR results were reviewed to assess and confirm MMR-D and MSI status.Results: MMR-D in PDAC is a rare event among PDAC patients (7/833), occurring at a frequency of 0.8%. Loss of MMR protein expression by IHC, high mutational load, and elevated MSIsensor scores were correlated with MMR-D PDAC. All 7 MMR-D PDAC patients in the study were found to have Lynch syndrome. Four (57%) of the MMR-D patients treated with immune checkpoint blockade had treatment benefit (1 complete response, 2 partial responses, 1 stable disease).Conclusions: An integrated approach of germline testing and somatic analyses of tumor tissues in advanced PDAC using NGS may help guide future development of immune and molecularly directed therapies in PDAC patients. Clin Cancer Res; 24(6); 1326-36. ©2018 AACR.

Mutation Detection in Patients With Advanced Cancer by Universal Sequencing of Cancer-Related Genes in Tumor and Normal DNA vs Guideline-Based Germline Testing

IMPORTANCE

Guidelines for cancer genetic testing based on family history may miss clinically actionable genetic changes with established implications for cancer screening or prevention.

OBJECTIVE

To determine the proportion and potential clinical implications of inherited variants detected using simultaneous sequencing of the tumor and normal tissue ("tumor-normal sequencing") compared with genetic test results based on current guidelines.

DESIGN, SETTING, AND PARTICIPANTS

From January 2014 until May 2016 at Memorial Sloan Kettering Cancer Center, 10 336 patients consented to tumor DNA sequencing. Since May 2015, 1040 of these patients with advanced cancer were referred by their oncologists for germline analysis of 76 cancer predisposition genes. Patients with clinically actionable inherited mutations whose genetic test results would not have been predicted by published decision rules were identified. Follow-up for potential clinical implications of mutation detection was through May 2017.

EXPOSURE

Tumor and germline sequencing compared with the predicted yield of targeted germline sequencing based on clinical guidelines.

MAIN OUTCOMES AND MEASURES

Proportion of clinically actionable germline mutations detected by universal tumor-normal sequencing that would not have been detected by guideline-directed testing.

RESULTS

Of 1040 patients, the median age was 58 years (interquartile range, 50.5-66 years), 65.3% were male, and 81.3% had stage IV disease at the time of genomic analysis, with prostate, renal, pancreatic, breast, and colon cancer as the most common diagnoses. Of the 1040 patients, 182 (17.5%; 95% CI, 15.3%-19.9%) had clinically actionable mutations conferring cancer susceptibility, including 149 with moderate- to high-penetrance mutations; 101 patients tested (9.7%; 95% CI, 8.1%-11.7%) would not have had these mutations detected using clinical guidelines, including 65 with moderate- to high-penetrance mutations. Frequency of inherited mutations was related to case mix, stage, and founder mutations. Germline findings led to discussion or initiation of change to targeted therapy in 38 patients tested (3.7%) and predictive testing in the families of 13 individuals (1.3%), including 6 for whom genetic evaluation would not have been initiated by guideline-based testing.

CONCLUSIONS AND RELEVANCE

In this referral population with selected advanced cancers, universal sequencing of a broad panel of cancer-related genes in paired germline and tumor DNA samples was associated with increased detection of individuals with potentially clinically significant heritable mutations over the predicted yield of targeted germline testing based on current clinical guidelines. Knowledge of these additional mutations can help guide therapeutic and preventive interventions, but whether all of these interventions would improve outcomes for patients with cancer or their family members requires further study.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01775072.

CDH1 Missense Variant c.1679C>G (p.T560R) Completely Disrupts Normal Splicing through Creation of a Novel 5' Splice Site

Disease-causing germline mutations in CDH1 cause Hereditary Diffuse Gastric Cancer (HDGC). For patients who meet the HDGC screening criteria, the identification and classification of the sequence variants found in CDH1 are critical for risk management of patients. In this report, we describe a germline CDH1 c.1679C>G (p.T560R) variant identified in a 50 year old man who was diagnosed with gastric cancer with a strong family history of gastric cancer (one living brother was diagnosed with gastric cancer at 63 and another brother died of gastric cancer at 45). cDNA analysis, involving fragment analysis and cloning, indicated that the p.T560R mutation created a novel 5’ splice donor site, which led to a novel transcript with a 32 nucleotide deletion in exon 11. This abnormal transcript putatively produces a truncated CDH1 protein (E-cadherin) of 575 amino acids instead of 882. We also demonstrated that the variant completely abolishes normal splicing as the mutant allele does not generate any normal transcript. Furthermore, the CDH1 c.1679C>G (p.T560R) variant segregated with gastric cancer in all three family members affected with gastric cancer in this family. These results support the conclusion that CDH1 c.1679C>G (p.T560R) variant is a pathogenic mutation and contributes to HDGC through disruption of normal splicing.

Genomic instability in pancreatic adenocarcinoma: a new step towards precision medicine and novel therapeutic approaches

Pancreatic cancer is one of the most challenging cancers. Whole genome sequencing studies have been conducted to elucidate the underlying fundamentals underscoring disease behavior. Studies have identified a subgroup of pancreatic cancer patients with distinct molecular and clinical features. Genetic fingerprinting of these tumors is consistent with an unstable genome and defective DNA repair pathways, which creates unique susceptibility to agents inducing DNA damage. BRCA1/2 mutations, both germline and somatic, which lead to impaired DNA repair, are found to be important biomarkers of genomic instability as well as of response to DNA damaging agents. Recent studies have elucidated that PARP inhibitors and platinum agents may be effective to induce tumor regression in solid tumors bearing an unstable genome including pancreatic cancer. In this review we discuss the characteristics of genomic instability in pancreatic cancer along with its clinical implications and the utility of DNA targeting agents particularly PARP inhibitors as a novel treatment approach.

An emerging entity: pancreatic adenocarcinoma associated with a known BRCA mutation: clinical descriptors, treatment implications, and future directions

BACKGROUND

BRCA1 and BRCA2 germline mutations are associated with an elevated risk for pancreas adenocarcinoma (PAC). Other BRCA-associated cancers have been shown to have greater sensitivity to platinum and poly(ADP-ribose) polymerase (PARP) inhibitors with better clinical outcomes than in sporadic cases; however, outcomes in BRCA-associated PAC have not been reported.

METHODS

Patients with a known BRCA1 or BRCA2 mutation and a diagnosis of PAC were identified from the Gastrointestinal Oncology Service, Familial Pancreas Cancer Registry, and Clinical Genetics Service at Memorial Sloan-Kettering Cancer Center.

RESULTS

Fifteen patients, five male, with a BRCA1 (n = 4) or BRCA2 (n = 11) mutation and PAC and one patient with a BRCA1 mutation and acinar cell carcinoma of the pancreas were identified. Seven female patients (70%) had a prior history of breast cancer. Four patients received a PARP inhibitor alone or in combination with chemotherapy; three demonstrated an initial radiographic partial response by Response Evaluation Criteria in Solid Tumors whereas one patient had stable disease for 6 months. Six patients received platinum-based chemotherapy first line for metastatic disease; five of those patients had a radiographic partial response.

CONCLUSION

BRCA mutation-associated PAC represents an underidentified, but clinically important, subgroup of patients. This is of particular relevance given the ongoing development of therapeutic agents targeting DNA repair, which may potentially offer a significant benefit to a genetically selected population. We anticipate that further study and understanding of the clinical and biologic features of BRCA-mutant PAC will aid in the identification of tissue biomarkers indicating defective tumor DNA repair pathways in sporadic PAC.

De novo CDH1 mutation in a family presenting with early-onset diffuse gastric cancer

In this report, we describe the first concluded case of a de novo germline mutation in CDH1 in a hereditary diffuse gastric cancer (HDGC) kindred. The incident case was a woman with a personal history of Hodgkin's lymphoma and diffuse gastric cancer, who was then confirmed to have a CDH1 mutation (c.1792 C>T (R598X)). The patient's mother was found to have the same CDH1 germline mutation; however, neither maternal grandparent was found to carry the mutation, thus leading to a conclusion that the proband's mother's mutation is of de novo origin. This case highlights the importance of recognition of the HDGC syndrome and of testing for CDH1 germline mutations in young individuals with diffuse gastric cancer without a family history of the disease.

Prevalence of BRCA1 and BRCA2 mutations in Ashkenazi Jewish families with breast and pancreatic cancer

BACKGROUND

Germline mutations in the BRCA2 cancer susceptibility gene are associated with an increased risk of pancreatic cancer (PC). Breast-pancreas cancer families with BRCA1 mutations have also been observed. The influence of a family history (FH) of PC on BRCA mutation prevalence in patients with breast cancer (BC) is unknown.

METHODS

A clinical database review (2000-2009) identified 211 Ashkenazi Jewish (AJ) BC probands who 1) underwent BRCA1/2 mutation analysis by full gene sequencing or directed testing for Ashkenazi founder mutations (BRCA1: 185delAG and 5382insC; BRCA2: 6174delT) and 2) had a FH of PC in a first-, second-, or third-degree relative. For each proband, the pretest probability of identifying a BRCA1/2 mutation was estimated using the Myriad II model. The observed-to-expected (O:E) mutation prevalence was calculated for the entire group.

RESULTS

Of the 211 AJ BC probands with a FH of PC, 30 (14.2%) harbored a BRCA mutation. Fourteen (47%) of the mutations were in BRCA1 and 16 (53%) were in BRCA2. Patients diagnosed with BC at age ≤ 50 years were found to have a higher BRCA1/2 mutation prevalence than probands with BC who were diagnosed at age > 50 years (21.1% vs 6.9%; P = .003). In patients with a first-, second-, or third-degree relative with PC, mutation prevalences were 15.4%, 15.3%, and 8.6%, respectively (P = .58). In the overall group, the observed BRCA1/2 mutation prevalence was 14.2% versus an expected prevalence of 11.8% (O:E ratio, 1.21; P = .15).

CONCLUSIONS

BRCA1 and BRCA2 mutations are observed with nearly equal distribution in AJ breast-pancreas cancer families, suggesting that both genes are associated with PC risk. In this population, a FH of PC was found to have a limited effect on mutation prevalence.

Germline PALB2 mutation analysis in breast-pancreas cancer families

BACKGROUND

Germline mutations in the PALB2 gene have been implicated in both breast cancer and pancreatic cancer susceptibility. The extent to which PALB2 mutations account for cancer susceptibility in breast-pancreas cancer families is unknown.

METHODS

High Resolution Melting analysis and Multiplex Ligation-dependent Probe Amplification were performed to investigate the prevalence of PALB2 mutations in patients with either a personal history of both breast and pancreatic cancer or a personal history of breast cancer and a family history of a first degree relative with pancreatic cancer.

RESULTS

No PALB2 mutations were identified in 77 breast-pancreas cancer families, which included 22 probands with a personal history of both breast and pancreatic cancer.

CONCLUSION

Mutations within the PALB2 gene are rare events that do not account for a substantial proportion of cancer susceptibility in breast-pancreas cancer families. Routine screening of breast-pancreas cancer families for the presence of PALB2 mutations appears to be low yield.

Clinical outcomes in pancreatic adenocarcinoma (PAC) associated with a known BRCA mutation

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Background: BRCA1 and -2 germ-line mutations are associated with increased risk of PAC; approximately 5% of all cases of PAC are estimated to be due to an inherited genetic mutation (Lynch, HT, et al. Pancreatology, 2001;1(5):466-471). Other BRCA-associated cancers have demonstrated increased sensitivity to platinum chemotherapy and PARP inhibitors (PARPi) with improved clinical outcomes compared to sporadic cases (J Clin Oncol, 2008 Dec 1;26(34):5530-6). Outcomes in BRCA-associated pancreatic cancer are unknown.

Methods: Patients with a known BRCA1 or -2 mutation and a diagnosis of PAC were retrospectively identified from the MSKCC Familial Pancreas Cancer Registry and via institutional database review. Outcomes and clinical characteristics were reviewed. 7 patients (1 male) with BRCA2 mutation and PAC, 4 patients (1 male) with BRCA1 mutation and PAC, were identified. Two further cases of BRCA mutation and cholangiocarcinoma were identified.

Results: See Table for patient demographics. Treatment for advanced disease included a PARP inhibitor (PARPi) in 2 cases; both pts had a radiologic partial response (PR) to therapy. Five patients received platinum-based chemotherapy for advanced disease, 4 of whom had a PR. Median survival for all patients was 27.6 months.

Conclusions: The use of platinum- containing chemotherapy, radiation therapy, and PARPi to target the BRCA-associated defective DNA repair mechanism is deserving of further investigation in these patients. PARPi have demonstrated promising efficacy in patients with BRCA-mutated breast and ovarian cancer and are undergoing prospective evaluation in PAC. Genetic testing in patients presenting with a personal history or strong family history of BRCA associated cancers may help to guide choice of therapy.

[Table: see text]

No significant financial relationships to disclose.