Germline Mutations In CHEK2 Research Articles

The correlation between tumor mutation burden and TP53 or CHEK2 germline mutations in malignant tumors.

e22527 Background: Li-Fraumeni syndrome (LFS) is a rare autosomal dominant cancer predisposition syndrome, mainly caused by the lack of tumor suppressor gene TP53. The LFS related tumors include breast cancer, brain tumors, malignant sarcoma, bone cancer and central nervous system tumors. In addition to TP53 germline mutations, studies have shown that CHEK2 is also a susceptibility gene for LFS, and CHEK2 germline mutations is related to a series of cancer types. However, the correlation between tumor mutation burden (TMB), age, gender, PD-L1 expression and TP53 or CHEK2 germline mutations in malignant tumors remains unknown. Methods: In this study, we retrospectively analyzed the mutation characteristics of TP53 or CHEK2 germline mutations in patients with solid tumors without selecting age or family history. We identified 631 patients harboring TP53 or CHEK2 mutations from 9337 patients with malignant solid tumors. According to the ACMG (American College of Medical Genetics and Genomics) guidelines in pathogenicity, the 631 patients in the retrospective cohort were divided into three groups, including P/LP group (with pathogenic or likely-pathogenic mutations), VUS group (with uncertain significance mutations) and B/LB group (with benign or likely-benign mutations). We also analyzed the differences in TMB, age, gender and PD-L1 expression among the three groups. Statistical significance was defined as P-value less than 0.05. Results: The 631 (631/9337) patients carried TP53 or CHEK2 germline mutations were identified, in which 33 patients with pathogenic mutations and 15 patients with likely-pathogenic mutations. These pathogenic or likely-pathogenic mutations mainly occurred in lung cancer, brain tumors, colorectal cancer and liver cancer, accounting for about 35.4%, 20.8%, 16.7% and 12.5%, respectively. Among the three groups, TMB was significantly different between P/LP group and B/LB group (P = 0.037), and the B/LB group was higher. In addition, we found that the three groups had no significant differences in age, gender and PD-L1 expression. Conclusions: Our data showed that 0.823% (48/8535) malignant solid tumor patients carried TP53 (28/48) or CHEK2 (20/48) germline pathogenic or likely_ pathogenic mutations. In addition, the TMB value in B/LB group was significantly higher than that in P/LP group. The other characteristics of LFS will be studied in the future.

Germline mutations in ATM, CHEK2, and other known/potential breast cancer susceptibility genes among BRCA-negative Uruguayan patients with breast cancer.

10596 Background: Breast cancer (BC) is the most frequent and the leading cause of death from cancer in Uruguayan women. In a previous study, we found BRCA1/2 germline mutations in less than 25% of the Uruguayan breast/ovarian cancer families studied. Due the impact and relevance of genetic testing in BC prevention and with the commitment to assure a wide accessibility, we developed genetic testing facilities at the University Hospital with the aim of analyzing and characterizing germline mutations in non BRCA known susceptibility and likely susceptibility genes. Methods: We studied 104 families who met the National Comprehensive Cancer Network (NCCN) criteria of hereditary BC. Analysis by next generation sequencing of BRCA1/2 genes revealed that 23 out of 104 cases studied (22%) carried pathogenic variants. Germline DNA from 42 cases BRCA negative was sequenced and analyzed for nine additional susceptibility genes (ATM, BARD1, CDH1, CHEK2, NBN, PALB2, PTEN, STK11 y TP53) included in a genetic panel. Also, in 24 cases negative for this panel we analyzed large deletions in BRCA1/2 by multiplex ligation-dependent probe amplification (MLPA) testing. In addition, to identify novel non-canonical causative genes, we extended our analysis to a complete exome sequencing of cases tested negative in genetic panels and MLPA analysis. Results: Among the 42 cases BRCA negative the sequencing of the extended genetic panel revealed 12 (28.8%) variants, 8 of uncertain significance (VUS) and 4 pathogenic, 2 novel (one in the ATM gene: NM_000051: c.614T > G and other in p53: NM_000546: c.245insT) and 2 previously reported (one in PALB2: NM_024675: c.2186insA and one in PALB2/1: NM_024675c.G7T genes). Regarding the VUS, it is worth highlighting the one found in exon 12 of CHEK2 (NM_007194: c.1333T > C) which was unusually frequent (16.7%) in our cohort when compared with public databases. Analysis of large deletions in BRCA1/2 in 24 cases without mutations in the genetic panel were negative for MLPA testing. Otherwise, complete exome sequencing of germline DNA from 22 cases negative for BRCA1/2 and for the genetic panel, revealed 18 variants, 16 that generate stop codons and 2 that generate loss of the termination codon (stoploss), suggesting a high potential for pathogenicity. Some striking examples are represented by the PSG2, CEP 135 y CEP 162, ZNF17 and ZNF260 genes. Conclusions: Of the 42 BRCA-negative cases, 4 (9.5%) carried a PV in a cancer susceptibility gene. The negative results obtained with MLPA in cases negative for BRCA and the extended genetic panel suggest that large deletions of BRCA are not a relevant cause of cancer susceptibility in this cohort. Otherwise, whole exome sequencing of 22 cases negatives for the previous genetic test showed pathogenic or probably PV in genes with no current evidence of association with breast and ovarian cancer.

A Case Report of CHEK2 and MUTYH Germline Mutations Associated With Cholangiocarcinoma in a Young Patient

Cholangiocarcinoma (CCA) is a major cause of primary liver carcinoma and has been associated with the penetrance of several germline mutations. We present a 31-year-old female evaluated for left upper quadrant pain and abnormal liver function tests. Ultrasound revealed a nodule in the liver, and biopsy showed intrahepatic adenocarcinoma. Germline testing was positive for two mutations: c.1100delC and c.1227_1228dupGG on the CHEK2 gene and the MUTYH gene, respectively. The patient was started on chemotherapy and tolerated it well. We aimed to demonstrate an association between CHEK2 and MUTYH mutations with CCA and highlight the importance of genetic testing for at-risk patients.

Abstract P2-09-16: Clinicopatological features and outcome of breast cancer in CHEK2 germline mutation carriers

Abstract Background: Carriers of CHEK2 germline mutations are at moderately increased (20-40%), lifetime risk for developing breast cancer (BC), in part depending on specific family history and mutation type and location. CHEK2 mutation associated BC is commonly associated with positive estrogen receptor(ER) tumor subtype, but other tumor features are less evident. Long term follow up and outcome of patients with CHEK2 -associated BC has not been reported. The clinical and tumoral features as well as and clinical outcome of a consecutive series of 57 BC patients (63 primary tumors) harboring pathogenic CHEK2 mutation is presented. Methods: Following IRB approval, hospital records from 3 major cancer centers in Israel were reviewed to identify female CHEK2 pathogenic/likely pathogenic sequence variant (P/LPSV) carriers who were diagnosed with BC between 2001-2021.Relevant clinical features, tumor data, treatment details and outcome were retrieved and. Mann-Whitney U-test was performed for continuous variables and descriptive statistics were used for non-continuous variables.Results:104 BC cases with documented CHEK2 sequence variant were obtained. 57 were carriers of CHEK2germline P/LPSV, and 63 primary tumors were diagnosed in these participants. Median age at diagnosis was 50 years (mean 51, range 31-73) and median follow up time of 23.5 months (mean 47,range 1-228). Six of 57 [10.5%] were diagnosed with synchronous bilateral tumors, and 6 [10.5%]with multifocal ipsilateral tumors. Twenty-three (41%) of the invasive tumors had positive regional lymph nodes at diagnosis and median tumor size was 1.2cm (mean 1.9, range 0.3-11.3cm). Seventy seven percent were invasive ducal carcinoma, 8% were invasive lobular, 11% DCIS, and two cases -unknown histology. Fifty-seven of 63 tumors (90%) were ER positive, and only two cases were triple negative. Ten (16%)tumors were HER2 positive. Most tumors (66%) were intermediate grade, 18% - low-grade, and 16%- high-grade tumors. Eighty percent opted for breast conserving surgery and 29 received chemotherapy, all were AC-T regimen, with anti HER2 agents in HER2 positive tumors. The most common PSV were c.1100delC (17 patients) and p.S428P (17 patients). Mean age at diagnosis for these two PSVs were 47 and 57 years, respectively (p=0.00438). Seven (12%) patients developed metastatic disease during the follow up period. Conclusion: This descriptive study shows some unique features of CHEK2 associated BC: early age at diagnosis(for the c.1100delC PSV) and high percentage of ER positivity. Synchronous and multifocal tumors were common. Further long term follow up and larger detailed description is warranted in this unique population. Citation Format: Shir Schlosser, Rinat Bernstein Molho, Natalia Karminsky, Daphna Barsuk, Yael Goldberg, Eitan Friedman, Rinat Yerushalmi, Keren Drumea, Inbal Kedar, Irina Jiveliouk, Merav Akiva Ben David. Clinicopatological features and outcome of breast cancer in CHEK2 germline mutation carriers [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-09-16.

The Mutational Landscape of Early-Onset Breast Cancer: A Next-Generation Sequencing Analysis.

BackgroundAround 5%–7% of breast cancer cases are diagnosed in women younger than 40, making it the leading cause of female cancer in the 25- to 39-year-old age group. Unfortunately, young age at diagnosis is linked to a more aggressive tumor biology and a worse clinical outcome. The identification of the mutational landscape of breast cancer in this age group could optimize the management.MethodsWe performed NGS analysis in paraffin blocks and blood samples of 32 young patients with breast cancer [<40 years] and 90 older patients during the period 2019 through 2021. All patients were treated in a single institution at the Oncology Department of “Alexandra” Hospital, Medical School, University of Athens, Greece.ResultsBreast tumors were characterized more frequently by HER2 overexpression [25% vs 18.9%], higher ki67 levels [75% vs 61%] and lower differentiation [71.9% vs 60%] in the younger group. PIK3CA [6/20; 30%] and TP53 [6/20; 30%] were the most frequent pathogenic somatic mutations identified in young patients, while one case of BRCA2 somatic mutation [1/20; 5%] and one case of PTEN somatic mutation [1/20; 5%] were also identified. PIK3CA mutations [16/50; 32%] and TP53 mutations [20/50; 40%] were the most common somatic mutations identified in older patients, however other somatic mutations were also reported (ATM, AKT, CHEK2, NRAS, CDKN2A, PTEN, NF1, RB1, FGFR1, ERBB2). As for germline mutations, CHEK2 [3/25; 12%] was the most common pathogenic germline mutation in younger patients followed by BRCA1 [2/25; 8%]. Of note, CHEK2 germline mutations were identified less frequently in older patients [2/61; 3%] among others [BRCA1 (2/61; 3%), ATM (2/61; 3%), APC (1/61; 1,6%) and BRCA2 (1/61; 1,6%)].ConclusionWe here report the mutational profile identified via NGS in patients with early-onset breast cancer compared to their older counterparts. Although the sample size is small and no statistically significant differences were detected, we highlight the need of genetic testing to most patients in this subgroup.

Identification of CHEK2 Germline Mutations in BRCA1/2- and PALB2-Negative Breast and Ovarian Cancer Patients

Introduction: The CHEK2 gene is known to be an important signal transducer involved in DNA repair, apoptosis, or cell cycle arrest in response to DNA damage. The mutations in this gene have been associated with a wide range of cancers, both sporadic and hereditary. Germline CHEK2 mutations are linked to an increased risk of breast cancer. Therefore, the aim of this study was to identify the prevalence of CHEK2 variants in BRCA1/2- and PALB2-negative early-onset patients with breast cancer and/or ovarian cancer in a Turkish population for the first time. Methods: The study included 95 patients with BRCA1/2- and PALB2-negative early-onset breast cancer and/or ovarian cancer and also 60 unaffected women. All the intron/exon boundaries and coding exons of CHEK2 were subjected to mutational analysis by heteroduplex analysis and DNA sequencing. Results: A total of 16 CHEK2 variants were found in breast cancer patients within the Turkish population. CHEK2 c.1100delC mutation most frequently studied in the CHEK2 gene was not detected in our study. The prevalence of variants of uncertain significance in CHEK2 was found to be 7.3% (n = 7) in BRCA1/2 and PALB2 mutation-negative Turkish patients with early-onset breast and/or ovarian cancer. Conclusion: The present study may shed light on alternative variations that could be significant for understanding the prevalence and clinical suitability of the CHEK2 gene.

Редкий случай злокачественного новообразования ассоциированного с герминальной мутацией в гене CHEK2. Клиническое наблюдение

An analysis of a series of population studies and the results of molecular genetic studies show that one of the predisposing factors in the development of cancer is the presence of a germline mutation. Monoallelic mutations in PALB2, CHEK2, and ATM may be associated with an increased risk of developing cancers other than breast cancer, as has been observed for BRCA1 and BRCA2, ovarian, and prostate cancers. A large body of evidence has now accumulated indicating that carriers of germline CHEK2 mutations face an increased risk of a variety of cancers that exhibit some specific clinicopathological characteristics. The paper presents data on the significance of germline mutations in the CHEK2 gene, as well as a clinical observation of a patient with a germline mutation in the CHEK2 gene and a developed malignant neoplasm. The above clinical observation makes it possible to establish a link between a germline mutation in the CHEK2 gene and the development of a rare malignant neoplasm at a young age in a patient. The paper reflects the need for genetic testing in healthy relatives of the patient for the presence of a germline mutation in the CHEK2 gene, which will allow for thorough screening measures for the early detection of malignant neoplasms.

Liposome-Encapsulated Cytarabine and Daunorubicin (CPX-351) Induces Remission in Newly Diagnosed Pediatric Secondary Myeloid Malignancies

Secondary myelodysplastic syndromes and acute myeloid leukemia (sMDS/AML) are rare myeloid neoplasms in children/adolescents and have a dismal prognosis. The mainstay therapy is hematopoietic cell transplantation (HCT) but there has been little therapeutic innovation for decades and outcomes remain poor. CPX-351, a fixed 5:1 molar ratio of liposomal cytarabine/daunorubicin, has shown favorable safety and efficacy in elderly individuals with sAML and children with relapsed de novo AML, which led the FDA to recently expand the label of CPX-351 to include pediatric patients with secondary AML, however, no data has been reported in this patient group. We report the outcomes of seven young patients with newly diagnosed sMDS/AML uniformly treated with CPX-351. Five patients had previously received chemotherapy for osteosarcoma, Ewing sarcoma, neuroblastoma, or T-ALL; one had predisposing genomic instability disorder (Cornelia de Lange syndrome); and one presented with MDS-related AML and multi-organ failure. The median age at diagnosis of myeloid malignancy was 17 (13-23) years. We identified somatic mutations and copy-number changes across 16 leukemia driver genes in six cases (including TP53 in two), abnormal karyotypes in six cases and rearrangements involving MECOM or NIM1K-TERT in two patients. Additional genomic studies identified pathogenic germline mutations in CHEK2 and SMC3 each in a single patient . Patients received 1-3 cycles of CPX-351 (100 units/m 2 on days 1, 3, and 5) resulting in complete morphologic remission without overt toxicity or treatment-related mortality. This approach allowed for adding FLT3 inhibitor as individualized therapy in one patient. Six patients were alive and leukemia-free at 0.51-3.25 years after HCT. One patient died from disease progression before HCT. Concluding, CPX-351 is an effective and well-tolerated regimen for cytoreduction in pediatric secondary myeloid malignancies warranting further investigation [Display omitted] DisclosuresTriplett: Miltenyi: Other: Travel, meeting registration.

Recurrent Germline Mutations of CHEK2 as a New Susceptibility Gene in Patients with Pheochromocytomas and Paragangliomas.

Purpose Recently, pheochromocytomas and paragangliomas (PPGLs) have been strongly suspected as hereditary tumors, as approximately 40% of patients carry germline mutations. In the cancers where defects occur to corrupt DNA repair and facilitate tumorigenesis, a CHEK2 strong association has been observed. Therefore, the purpose of this study was to investigate the effect of CHEK2 mutations for its possible pathogenicity in PPGLs. Methods Four patients with CHEK2 mutations were recruited, as previously detected by the whole exome sequencing. Sanger sequencing was used to verify the germline mutations as well as the loss of heterozygosities (LOHs) in their somatic DNAs. Immunohistochemistry was used to analyze the expression of CHEK2 and its downstream target p53 Ser20 (phosphorylated p53). Results The average age of studied patients was 44.25 ± 11.18 years, at the time diagnosis. One patient had multiple tumors which recurred quickly, while two patients had distant metastasis. None of the patient had any relevant family history. Four germline CHEK2 mutations were identified (c.246_260del; c.715G > A; c.1008+3A > T; and c.1111C > T). All the patients were predicted to have either pathogenic or suspected pathogenic mutations. There was no LOH of CHEK2 gene in somatic DNAs found. Additionally, neither CHEK2 proteins nor its downstream target p53 Ser20 were expressed in the tumor tissues. The inactivation of CHEK2 leads to the decrease in the p53 phosphorylation, which might promote tumorigenesis. Conclusions For the first time, CHEK2 was identified as a susceptibility gene for PPGLs. However, the penetrance of CHEK2 gene with genotype-phenotype correlation needs to be investigated.

1816P CHEK2 gene somatic loss in breast tumors from carriers of germline CHEK2 mutations

CHEK2-associated neoplasms account for a significant proportion of hereditary breast cancer (BC). The contribution of loss of heterozygosity (LOH) phenomenon to the pathogenesis of CHEK2-dependent tumors remains poorly understood, and almost all available data concern only one mutation type - CHEK2 1100delC.

Abstract 2182: Evaluation of somatic and germline mutations in ampullary carcinoma reveals actionable targets in multiple signaling pathways

Abstract Background: Ampullary carcinoma (AC) is a rare gastrointestinal cancer with few effective standard treatment options. For patients with unresectable diseases, the response rates for radiotherapy, chemotherapy, and chemoradiotherapy are low. Evaluation of the actionable mutations through genomic profiling will enable patients to enroll in matched clinical trials. Methods: To characterize actionable targets in 27 Chinese AC patients, a 500-gene next-generation sequencing panel was applied to assess the mutational status of their tumor tissues, including SNV, insertions/deletions, CNV and re-arrangements. Also, paired genomic DNA sample was extracted and analyzed by a 93-gene NGS panel to characterize germline variants. Results: Recurrent somatic mutated genes were KRAS (63%), TP53 (59%), APC (26%), SMAD4 (19%), CDKN2A (15%), ELF3 (11%), ERBB2 (11%), ERBB3 (11%) and MAP2K4 (11%). Consistent with previous studies, all mutations in AC driver gene ELF3 (n =3) were inactivating (three indels and one in splicing-site). The median tumor mutation burden (TMB) of our cohort was 1.6 (0-6.1) mutations/Mb and none of our patients had high microsatellite instability (MSI-H). Overall, we observed a wide spectrum of hotspot mutations in cancer driver genes including ERBB3 (n =2), FBXW7 (n =2), U2AF1 (n =2), BRAF (n =1), ERBB2/HER2 (n =1) and PIK3CA (n =1). The HER2 R678Q mutation, located in the transmembrane domain (TMD), activated HER2 signaling by improving the active dimer interface or stabilizing an activating conformation of HER2. Interestingly, both ERBB3 mutations (G284R and D297Y) were located in the extracellular domain (ECD) and their oncogenic activity also depended on the kinase-activity of ERBB2. These three mutations, together with one case of ERBB2 amplification, can be targeted by anti-HER2 antibodies and small-molecule HER2 kinase inhibitors. The BRAF N581I mutation is resistant to BRAF inhibitor vemurafenib but sensitive to MEK inhibitor trametinib. The PIK3CA N1044K mutation is oncogenic but its sensitivity to PIK3CA inhibitor alpelisib is unknown. Additionally, one patient had high level of FGFR2 amplification which may be suitable for the clinical trials of FGFR2 inhibitors pemigatnib and erdafitnib. Furthermore, two patients carried loss-of-function germline mutations in DNA repair genes PALB2 and CHEK2 which may confer synthetic lethality with PARP inhibitors. Taken together, at least eight (29.6%) patients in our cohort had actionable therapeutic targets. Conclusions: Through comprehensive genomic characterization of Chinese AC patients, we identified multiple actionable mutations in multiple signaling pathways. Our findings indicated that molecular profiling can provide clinical benefits to a significant portion of AC patients. Citation Format: Fei Wang, Si Liu, Xiaomo Li, Zhiming Zhao, Tonghui Ma, Hongling Yuan, Rong Liu. Evaluation of somatic and germline mutations in ampullary carcinoma reveals actionable targets in multiple signaling pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2182.

Presence of Rare Germline Variants in Fanconi Anaemia Pathway Genes Confers a Poor Prognosis Comparable to TP53 Mutations in Therapy-Related Myeloid Neoplasms

Introduction: T-MN inclusive of therapy related myelodysplastic syndrome (T-MDS) and acute myeloid leukemia (T-AML) are aggressive neoplasms occurring after exposure to chemo (CT) and/or radiotherapy (RT) and are characterized by high frequency of complex cytogenetics and poor prognosis. TP53 and other genes involved in DNA repair such as Fanconi Anaemia(FANC) pathway are critical in maintaining genomic stability. TP53 mutations are associated with complex karyotype and poor prognosis in myeloid malignancies. Further, variants in the FANC pathway are a risk factor for malignancies, but remain less well studied in T-MN. Churpek et al . (Cancer 2016) reported germline mutations in BRCA1, BRCA2, TP53, CHEK2 and PALB2 in 8/43 (19%) treated breast cancer patients who developed T-MN. However, their interaction with TP53 mutations and impact on survival is unknown. Here we investigate the genomic architecture of T-MN patients from the South Australian Myelodysplastic Syndrome (SA-MDS) registry.Methods: Demographic, clinical and laboratory data including cytogenetic profile of 147 T-MN patients were analysed. Targeted Massively Parallel Sequencing of a custom panel of 63 genes (43 myeloid neoplasms associated genes & 20 FANC; all coding regions) was performed on diagnosis bone marrow samples from 101 T-MN samples. Rare FANC variants were selected based ExAC MAF <0.2% and variants only with VAL ≥20% were selected for further analysis. FANC variants were called deleterious if predicted to be deleterious by atleast two in-silico prediction model (e.g. CADD, SIFT, POLYPHEN and Mutation taster) and/or reported in COSMIC, gene specific databases or in literature.Results: Median age of T-MN was 71 (20-91) years and the most frequent primary neoplasms were lymphoproliferative neoplasms (n=56, 38%) and prostate cancer (n=22, 15%). Sixty-three (43%), 34 (23%) and 48(33%) patients received CT, RT and CT plus RT respectively. The T-MN group consisted of 104 T-MDS (71%) and 43 T-AML (29%). Poor risk cytogenetics were more frequent in T-MN cases following CT than after RT alone.Somatic mutations in myeloid genes were detected in 95/101 (94%) of T-MN cases. Notably, all normal karyotype T-MN (29/29, 100%) were mutated. Mutations were most frequently seen in transcriptional factors (35%), TP53 (32%) and splicing factors (26%). Significantly higher proportion of TP53mut T-MN patients had complex karyotype (22/32, 84%) compared to TP53wt (5/69; 7%, p<0.0001).Examination of 20 FANC pathway genes identified 38 rare variants in 31(31%) T-MN at a variant allele frequency (VAF) of ≥20% and most of the variants were missense (35/38; 92%). These were mostly seen in BRCA1, FANCA, FANCM, BRCA2, FANCL and SLX4 genes. Of patients with FANC variants, 42% (13/31) had concomitant TP53 mutations. The median VAF was 49% (range 20-100%) with no significant difference between the deleterious (n=13; 34%) and non-deleterious variants (n=25). Out of 13 deleterious variants (including 2 BRCA1 variants previously reported pathogenic on BIC database), ten variants were seen in nine TP53wt patients. We compared the disease characteristics, prior chemotherapy and survival outcome in patients with TP53mut (n=32), TP53wt harbouring predicted deleterious FANC variants (TP53wt /FANCdel var; n=9), TP53wt harbouring predicted non-deleterious FANC variants (TP53wt /FANCnon-del var; n=9) and TP53wt /FANCwt (n=51). There was no difference in bone marrow blast %, type of prior malignancy, prior therapy (CT vs RT vs combination), proportion of T-AML and treatment for T-MN between the groups. Interestingly, median number of mutations were significantly lower in TP53mut group (1; range 0-11) compared to TP53wt /FANCdel var, TP53wt /FANCnon-del var (both groups - 3; range 0-6) and TP53wt /FANCwt (3; range 0-9) (p=0.0005). Importantly, median OS of TP53wt /FANCdel var and TP53wt /FANCnon-del var groups was identical and significantly shorter than TP53wt /FANCwt (9.7 vs. 9.9 vs. 19.1 months; p=0.00485), and similar to TP53mut group (8.9 months).Conclusions: In our cohort, somatic mutations were seen in 90% of T-MN patients, comparable to primary MDS, contrary to previously published literature. Somatic TP53 mutations and FANC variants are seen in 32% and 31% of cases respectively and 13% harboring both. This study demonstrating that rare FANC variants are associated with significantly poor survival comparable to TP53 mutated T-MN patients. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

TP53 and CHEK2 germline mutations in malignant solid tumors.

3119 Background: Li-Fraumeni syndrome (LFS, OMIM #151623) is an autosomal dominant cancer predisposition syndrome. Typical LFS tumors comprise adrenocortical carcinomas, sarcoma, breast cancer and central nervous system tumors. LFS is also associated with an increased risk of a multitude of other common types of cancer, such as prostate cancer, lung cancer, gastric cancer, colorectal cancer, ovarian cancer, melanoma, etc. TP53 germline mutations are the most common gene with LFS. Germline mutations of CHEK2 have been identified as another predisposing gene and associated with a range of cancer types. However, the pattern of TP53 and CHEK2 germline mutations in malignant tumors remains unknown. Methods: We identified 8535 malignant solid tumors patients without selecting age or family history in a retrospective cohort. Germline mutations were categorized based on ACMG (American College of Medical Genetics and Genomics) guidelines in pathogenicity. The patients were divided into three groups, P group (with pathogenic mutations), LP group (with likely-pathogenic mutations) and Non_P group (neither pathogenic nor likely-pathogenic mutation). Statistical significance was defined as P-value less than 0.05. Results: A total of 461 (461/8535) patients carried TP53 or CHEK2 germline mutations were identified, in which 15 patients with pathogenic mutations and 17 patients with likely-pathogenic mutations. One patient with lung cancer in LP group carried TP53 homozygous mutation ( p. Ser215Ile), and the remaining 31 patients all carried heterozygous mutations. Among these 31 carriers, 16 (51.6%) carried nonsense or missense mutations (10 for nonsense and 6 for missense mutations). 3 patients in the P group carried CHEK2 p. Y139* (one liver cancer patient and two lung cancer patients) were identified. The median age of group P, LP and Non_P was 55 (39 for TP53, 61 for CHEK2), 63 (52 for TP53, 66 for CHEK2) and 59, respectively. Somatic mutation analysis found no significant difference in tumor mutation burden (TMB) among three groups. The SNV/INDEL mutation frequency of LRP1B in the P or LP group was significantly lower than the Non_P group. Conclusions: Our data showed that 0.375% (32/8535) malignant solid tumor patients carried TP53 (16/8535) or CHEK2 (16/8535) germline pathogenic or likely-pathogenic mutations. The relationship between germline mutations and cancer susceptibility will be studied in the future.[Table: see text]

The somatic mutation landscape of germline CHEK2-altered prostate cancer.

5084 Background: The intersection between germline and somatic genomics is an evolving field in which germline mutations may predispose to unique patterns of subsequent somatic mutations in cancer. Germline mutations in CHEK2, involved in cell cycle regulation and DNA damage response, are associated with an increased risk of prostate cancer (PCa), while somatic-only CHEK2 alterations in PCa are rare. The association of germline CHEK2 (g CHEK2)-altered PCa with somatic mutations is unknown, and may inform hypotheses about the etiology of these cancers. Methods: Germline DNA sequencing of 1,042 consecutive PCa patients (pts) from the public SignalDB database (www.signaldb.org) was analyzed for prevalence of pathogenic g CHEK2 mutations and was compared to individuals from the general population estimated by the ExAC database (containing 53,105 germline exomes). A separate cohort of 33 PCa pts from Johns Hopkins (JH) with known g CHEK2 mutations and available somatic tumor DNA sequencing (from primary prostatic tissue) was used to assess the association of g CHEK2 mutations with somatic mutations in genes that are recurrently altered in PCa ( TP53, RB1, PTEN, ATM, BRCA1/2, and CDK12); the prevalence of these somatic alterations was compared to those in 333 unselected PCa pts from the TCGA cohort. Somatic biallelic inactivation of CHEK2 was analyzed in a subset of pts. After uncovering a potential link between g CHEK2 and somatic CDK12 mutations, we studied a cohort of 69 pts with somatic CDK12 mutations where germline data were also available. Results: 28 of 1,042 (2.7%) PCa pts from SignalDB had a pathogenic g CHEK2 mutation, compared to a population prevalence (in ExAC) of 1.4% (750 of 53,105) (RR 1.9, 95%CI 1.3–2.8, P&lt; 0.001). Strikingly, only 23.8% of pts from SignalDB with g CHEK2 mutations had biallelic inactivation in the tumor . Furthermore, none of the 33 g CHEK2 pts from the JH cohort had evidence of somatic LOH. There were no differences in mutation prevalences involving TP53, RB1, PTEN, ATM, and BRCA1/2 between g CHEK2-altered and non-altered PCa pts. Unexpectedly, 5 of 33 (15%) g CHEK2-altered pts from the JH cohort had a somatic CDK12 mutation, compared to only 3 of 333 CDK12 mutations (1%) in unselected PCa pts from the TCGA cohort (RR 16.8, 95%CI 4.2–67, P&lt; 0.001). Conversely, 11 of 69 (16%) pts with a somatic CDK12 mutation harbored a pathogenic g CHEK2 mutation, compared to 28 of 1,042 (2.7%) unselected PCa pts from SignalDB (RR 5.9, 95%CI 3.1–11.4, P&lt; 0.001). Conclusions: Prostate cancers from g CHEK2-altered pts are infrequently characterized by biallelic CHEK2 inactivation and may be enriched for somatic CDK12 mutations, suggesting a unique mechanism of carcinogenesis that is different from g BRCA2-altered pts. Conversely, somatic CDK12-mutated cancers may be enriched for g CHEK2 mutations. The co-occurrence of CHEK2 and CDK12 mutations suggests a synergistic role in promoting cancer growth.

Clinicopathologic Profile of Breast Cancer in Germline ATM and CHEK2 Mutation Carriers.

The most common breast cancer (BC) susceptibility genes beyond BRCA1/2 are ATM and CHEK2. For the purpose of exploring the clinicopathologic characteristics of BC developed by ATM or CHEK2 mutation carriers, we reviewed the archive of our Family Cancer Clinic. Since 2018, 1185 multi-gene panel tests have been performed. Nineteen ATM and 17 CHEK2 mutation carriers affected by 46 different BCs were identified. A high rate of bilateral tumors was observed in ATM (26.3%) and CHEK2 mutation carriers (41.2%). While 64.3% of CHEK2 tumors were luminal A-like, 56.2% of ATM tumors were luminal B-like/HER2-negative. Moreover, 21.4% of CHEK2-related invasive tumors showed a lobular histotype. About a quarter of all ATM-related BCs and a third of CHEK2 BCs were in situ carcinomas and more than half of ATM and CHEK2-related BCs were diagnosed at stage I-II. Finally, 63.2% of ATM mutation carriers and 64.7% of CHEK2 mutation carriers presented a positive BC family history. The biological and clinical characteristics of ATM and CHEK2-related tumors may help improve diagnosis, prognostication and targeted therapeutic approaches. Contralateral mastectomy should be considered and discussed with ATM and CHEK2 mutation carriers at the first diagnosis of BC.

Germline Mutations in Other Homologous Recombination Repair-Related Genes Than BRCA1/2: Predictive or Prognostic Factors?

The homologous recombination repair (HRR) pathway repairs double-strand DNA breaks, mostly by BRCA1 and BRCA2, although other proteins such as ATM, CHEK2, and PALB2 are also involved. BRCA1/2 germline mutations are targeted by PARP inhibitors. The aim of this commentary is to explore whether germline mutations in HRR-related genes other than BRCA1/2 have to be considered as prognostic factors or predictive to therapies by discussing the results of two articles published in December 2020. The TBCRC 048 trial published by Tung et al. showed an impressive objective response rate to olaparib in metastatic breast cancer patients with germline PALB2 mutation compared to germline ATM and CHEK2 mutation carriers. Additionally, Yadav et al. observed a significantly longer overall survival in pancreatic adenocarcinoma patients with germline HRR mutations compared to non-carriers. In our opinion, assuming that PALB2 is a high-penetrant gene with a key role in the HRR system, PALB2 mutations are predictive factors for response to treatment. Moreover, germline mutations in the ATM gene provide a better outcome in pancreatic adenocarcinoma, being more often associated to wild-type KRAS. In conclusion, sequencing of HRR-related genes other than BRCA1/2 should be routinely offered as part of a biological characterization of pancreatic and breast cancers.

Generation of two induced pluripotent stem cell lines from blood cells of a prostate cancer patient carrying germline mutation in CHEK2

Germline mutations of CHEK2 have been reported in various types of disease including breast cancer, ovarian cancer, colorectal cancer and prostate cancer. We generated two iPSC lines ZNHi001-A and ZNHi001-B from a prostate cancer patient carrying germline mutation in CHEK2 (c.667C＞T, also p.R223C) which may increase the risk of prostate cancer. Pluripotency and multi-lineage differentiation capacity of the two iPSC lines were confirmed by gene expression and teratoma assay. The generated iPSC lines carrying specific CHEK2 mutation might be a useful resource to study the pathogenic mechanism and develop potential therapeutic strategy of prostate cancer.

Delayed Craniospinal Metastasis of Aggressive Nonfunctioning Pituitary Adenomas as Pituitary Carcinomas.

Background Clinical behavior of pituitary neoplasms is peculiar and notoriously difficult to predict. While aggressive tumors are common, metastasis is very rare, can be highly delayed, and there are no histological or clinical features to meaningfully predict this happening. Endocrinologically silent tumors are particularly difficult, as there is less opportunity to detect early metastasis. Together, this amounts to a situation of uncertainty over the appropriate management of such tumors before and after metastasis. Case Description The authors report two cases of nonfunctioning aggressive pituitary adenoma (APA) each requiring two transsphenoidal surgeries, a transcranial resection and radiotherapy. Both these tumors subsequently metastasized caudally along the neuraxis, years later, as a null cell carcinoma associated with a germline CHEK2 mutation and a silent Crooke's cell carcinoma. The former represents a novel oncogenetic association. Conclusion Delayed drop dural metastasis of pituitary carcinoma is becoming increasingly recognized. Surgical resection of the distant disease to confirm the diagnosis and relieve the mass effect, followed by temozolomide chemotherapy, is the current treatment of choice. The need for both long-term follow-up in patients with APA, and a high degree of suspicion toward dural-based radiographic findings is emphasized.

Recurrent Mutations in BRCA1, BRCA2, RAD51C, PALB2 and CHEK2 in Polish Patients with Ovarian Cancer.

Simple SummaryIn Poland, ovarian cancer is the fourth leading cause of death from cancer among women. Several founder mutations in the BRCA1, BRCA2, PALB2, RAD51C, and CHEK2 genes are associated with breast and ovarian cancer. The aim of the study was to analyze the frequency and magnitude of association of 21 recurrent founder germline mutations in the above genes with ovarian cancer risk among unselected patients in Poland. The ovarian cancer risk was associated with mutations in BRCA1, BRCA2, RAD51C, and PALB2 but not in the CHEK2 gene. Excluding CHEK2, pathogenic mutations in the other 18 alleles were present in 12.5% of cases and 0.6% of healthy controls. A mutation was found in 25.8% of familial cases vs. 9.9% of non-familial cases. We recommend that in Poland all women with ovarian cancer and first-degree female relatives should be tested for the panel of 18 founder mutations in BRCA1, BRCA2, PALB2, and RAD51C.The aim of the study was to analyze the frequency and magnitude of association of 21 recurrent founder germline mutations in BRCA1, BRCA2, PALB2, RAD51C, and CHEK2 genes with ovarian cancer risk among unselected patients in Poland. We genotyped 21 recurrent germline mutations in BRCA1 (9 mutations), BRCA2 (4 mutations), RAD51C (3 mutations), PALB2 (2 mutations), and CHEK2 (3 mutations) among 2270 Polish ovarian cancer patients and 1743 healthy controls, and assessed the odds ratios (OR) for developing ovarian cancer for each gene. Mutations were detected in 369 out of 2095 (17.6%) unselected ovarian cancer cases and 117 out of 1743 (6.7%) unaffected controls. The ovarian cancer risk was associated with mutations in BRCA1 (OR = 40.79, 95% CI: 18.67–114.78; p = 0.29 × 10−15), in BRCA2 (OR = 25.98; 95% CI: 1.55–434.8; p = 0.001), in RAD51C (OR = 6.28; 95% CI 1.77–39.9; p = 0.02), and in PALB2 (OR 3.34; 95% CI: 1.06–14.68; p = 0.06). There was no association found for CHEK2. We found that pathogenic mutations in BRCA1, BRCA2, RAD51C or PALB2 are responsible for 12.5% of unselected cases of ovarian cancer. We recommend that all women with ovarian cancer in Poland and first-degree female relatives should be tested for this panel of 18 mutations.

Incidence of the CHEK2 Germline Mutation and Its Impact on Clinicopathological Features, Treatment Responses, and Disease Course in Patients with Papillary Thyroid Carcinoma

Simple SummaryThe aim of our study was to evaluate whether the CHEK2 mutation was a predictor of poorer clinical course in patients with papillary thyroid cancer. The study included 1547 patients from a single center in Poland, in whom the presence and variant of the CHEK2 mutation were determined. Two hundred and forty patients were found to carry this mutation. We found significant association of the CHEK2 truncating variant with vascular invasion and intermediate or high initial risk of recurrence/persistence, whereas this relationship was not found in case of the missense CHEK2 variant. Neither the truncating nor the missense mutations were associated with worse primary treatment response and outcome of the disease.The CHEK2 gene is involved in the repair of damaged DNA. CHEK2 germline mutations impair this repair mechanism, causing genomic instability and increasing the risk of various cancers, including papillary thyroid carcinoma (PTC). Here, we asked whether CHEK2 germline mutations predict a worse clinical course for PTC. The study included 1547 unselected PTC patients (1358 women and 189 men) treated at a single center. The relationship between mutation status and clinicopathological characteristics, treatment responses, and disease outcome was assessed. CHEK2 mutations were found in 240 (15.5%) of patients. A CHEK2 I157T missense mutation was found in 12.3%, and CHEK2 truncating mutations (IVS2 + 1G > A, del5395, 1100delC) were found in 2.8%. The truncating mutations were more common in women (p = 0.038), and were associated with vascular invasion (OR, 6.91; p < 0.0001) and intermediate or high initial risk (OR, 1.92; p = 0.0481) in multivariate analysis. No significant differences in these parameters were observed in patients with the I157T missense mutation. In conclusion, the CHEK2 truncating mutations were associated with vascular invasion and with intermediate and high initial risk of recurrence/persistence. Neither the truncating nor the missense mutations were associated with worse primary treatment response and outcome of the disease.