Molecular characterization of pleomorphic mesothelioma: a multi-institutional study.

The molecular alterations of pleomorphic mesotheliomas are largely unknown. In the present study, we performed whole-exome sequencing (WES) on 24 pleomorphic mesotheliomas in order to better characterize the molecular profile of this rare histologic variant. BAP1 protein expression and CDKN2A deletion by FISH were also evaluated. Significantly mutated genes included BAP1 (35%), NF2 (13%), LATS2 (8%), TP53 (5%), and LATS1 (3%). BAP1 alterations most frequently co-occurred with deletions of chromosomes 4, 9, and 13. Other important genetic alterations in pleomorphic mesotheliomas included truncating mutations in NF2 (3 of 24; 12.5%), LATS2 (2 of 24; 8%), TP53 (1 of 24; 4%), and PBRM1 (1 of 24; 4%). Focal losses of chromosome 9p21 were most common copy number alterations (11 of 24 cases; 46%), and were assessed by WES and targeted FISH. The second most common were deletions of chromosome 4 (8 of 24; 33% pleomorphic mesotheliomas). Three cases of pleomorphic mesothelioma did not show any mutations, copy number alterations, or LOH. This first WES analysis of pleomorphic mesotheliomas did not identify novel or unique mutations. In contrast to transitional mesothelioma that was reclassified as sarcomatoid variant based on transcriptome data, pleomorphic mesotheliomas are molecularly heterogeneous and therefore their reclassification into single subtype is more difficult.

Liquid biopsy of cerebrospinal fluid for MYD88 L265P mutation is useful for diagnosis of central nervous system lymphoma.

The current standard of diagnosing central nervous system (CNS) lymphoma is stereotactic biopsy, however the procedure has a risk of surgical complication. Liquid biopsy of the CSF is a less invasive, non-surgical method that can be used for diagnosing CNS lymphoma. In this study, we established a clinically applicable protocol for determining mutations in MYD88 in the CSF of patients with CNS lymphoma. CSF was collected prior to the start of chemotherapy from 42 patients with CNS lymphoma and matched tumor specimens. Mutations in MYD88 in 33 tumor samples were identified using pyrosequencing. Using 10 ng each of cellular DNA and cell-free DNA (cfDNA) extracted from the CSF, the MYD88 L265P mutation was detected using digital PCR. The conditions to judge mutation were rigorously determined. The median Target/Total value of cases with MYD88 mutations in the tumors was 5.1% in cellular DNA and 22.0% in cfDNA. The criteria to judge mutation were then determined, with a Target/Total value of 0.25% as the cutoff. When MYD88 mutations were determined based on these criteria, the sensitivity and specificity were 92.2% and 100%, respectively, with cellular DNA; and the sensitivity and specificity were 100% with cfDNA. Therefore, the DNA yield, mutated allele fraction, and accuracy were significantly higher in cfDNA compared with that in cellular DNA. Taken together, this study highlights the importance of detecting the MYD88 L265P mutation in cfDNA of the CSF for diagnosing CNS lymphoma using digital PCR, a highly accurate and clinically applicable method.

Ultrasensitive detection of tumor-specific mutations in saliva of patients with oral cavity squamous cell carcinoma.

BACKGROUND: Oral cavity squamous cell carcinoma (OCSCC) is the most common head and neck malignancy. Although the survival rate of patients with advanced-stage disease remains approximately 20% to 60%, when detected at an early stage, the survival rate approaches 80%, posing a pressing need for a well validated profiling method to assess patients who have a high risk of developing OCSCC. Tumor DNA detection in saliva may provide a robust biomarker platform that overcomes the limitations of current diagnostic tests. However, there is no routine saliva-based screening method for patients with OCSCC. METHODS: The authors designed a custom next-generation sequencing panel with unique molecular identifiers that covers coding regions of 7 frequently mutated genes in OCSCC and applied it on DNA extracted from 121 treatment-naive OCSCC tumors and matched preoperative saliva specimens. RESULTS: By using stringent variant-calling criteria, mutations were detected in 106 tumors, consistent with a predicted detection rate ≥88%. Moreover, mutations identified in primary malignancies were also detected in 93% of saliva samples. To ensure that variants are not errors resulting in false-positive calls, a multistep analytical validation of this approach was performed: 1) re-sequencing of 46 saliva samples confirmed 88% of somatic variants; 2) no functionally relevant mutations were detected in saliva samples from 11 healthy individuals without a history of tobacco or alcohol; and 3) using a panel of 7 synthetic loci across 8 sequencing runs, it was confirmed that the platform developed is reproducible and provides sensitivity on par with droplet digital polymerase chain reaction. CONCLUSIONS: The current data highlight the feasibility of somatic mutation identification in driver genes in saliva collected at the time of OCSCC diagnosis.

SIDR: simultaneous isolation and parallel sequencing of genomic DNA and total RNA from single cells.

Simultaneous sequencing of the genome and transcriptome at the single-cell level is a powerful tool for characterizing genomic and transcriptomic variation and revealing correlative relationships. However, it remains technically challenging to analyze both the genome and transcriptome in the same cell. Here, we report a novel method for simultaneous isolation of genomic DNA and total RNA (SIDR) from single cells, achieving high recovery rates with minimal cross-contamination, as is crucial for accurate description and integration of the single-cell genome and transcriptome. For reliable and efficient separation of genomic DNA and total RNA from single cells, the method uses hypotonic lysis to preserve nuclear lamina integrity and subsequently captures the cell lysate using antibody-conjugated magnetic microbeads. Evaluating the performance of this method using real-time PCR demonstrated that it efficiently recovered genomic DNA and total RNA. Thorough data quality assessments showed that DNA and RNA simultaneously fractionated by the SIDR method were suitable for genome and transcriptome sequencing analysis at the single-cell level. The integration of single-cell genome and transcriptome sequencing by SIDR (SIDR-seq) showed that genetic alterations, such as copy-number and single-nucleotide variations, were more accurately captured by single-cell SIDR-seq compared with conventional single-cell RNA-seq, although copy-number variations positively correlated with the corresponding gene expression levels. These results suggest that SIDR-seq is potentially a powerful tool to reveal genetic heterogeneity and phenotypic information inferred from gene expression patterns at the single-cell level.

Selective Chemical Labeling and Sequencing of 5-Carboxylcytosine in DNA at Single-Base Resolution.

5-Carboxylcytosine (5caC) plays a vital role in the dynamics of DNA demethylation, and sequencing of its sites will help us dig out more biological functions of 5caC. Herein, we present a novel chemical method to efficiently label 5caC distinguished from other bases in DNA. Combined with bisulfite sequencing, 5caC sites can be located at single-base resolution, and the efficiency of 5caC labeling is 92% based on the Sanger sequencing data. Furthermore, dot blot assays have confirmed that 5caC-containing DNA isolated from HeLa cells was successfully labeled using our method. We expect that our strategy can be further applied to selectively tagging other carboxyl-modified bases and mapping their sites in RNA.

Feasibility of tumor testing for BRCA status in high-grade serous ovarian cancer using fresh-frozen tissue based approach.

OBJECTIVE: For many years, BRCA mutational status has only been considered as a predictor of ovarian cancer susceptibility and as a prognostic factor. Nonetheless, in the era of precision medicine, it has also become a predictive biomarker of response to platinum-based-chemotherapy and, more recently, to PARP-inhibitors, also in the frontline setting. We assessed the feasibility of a fresh frozen tissue-based-BRCA-screening workflow in a tertiary referral center. METHODS: We consecutively enrolled a series of 456 newly diagnosed FIGO-Stage IIIC-IV, high grade serous-ovarian cancer patients. All patients receiving tumor-biopsy underwent tBRCA-testing. RESULTS: Clinically relevant tissue-BRCA (tBRCA) variants were observed in 145 women (31.8%), particularly we recognized 89 (61.4%) patients with BRCA1-pathogenetic variants (PVs) and 56 women (38.6%) with BRCA2-PVs. Among 292 tBRCA wild-type (wt) patients, 88 cases were germline BRCA tested (gBRCA) and 86 (97.8%) were confirmed as gBRCAwt, while 1 (1.1%) had gBRCA variant of uncertain significance and 1 had gBRCA mutation (1.1%). The concordance of tumor test versus germline BRCA test was 86.3% (209/242). Large genomic rearrangements (LGRs) were suspected in 13/292 tBRCAwt patients (4.5%) by using bioinformatic algorithm and multiplex ligation-dependent probe amplification (MLPA) was performed, with evidence of PVs in only 1 case. CONCLUSIONS: Fresh-frozen tissue-based BRCA screening workflow is feasible and reliable. It allows to enlarge the BRCA mutated population that might receive PARPi with the greatest benefit, without missing cascade testing for family members and therefore, maintaining its preventive role.

Analysis of DNA methylation in endometrial biopsies to predict risk of endometrial cancer.

OBJECTIVE: To determine whether analysis of methylated DNA in benign endometrial biopsy (EB) specimens is associated with risk of endometrial cancer (EC). METHODS: We identified 23 women with EBs performed at Mayo Clinic diagnosed as normal (n = 14) or hyperplasia (n = 9) and who later developed endometrial cancer after a median interval of 1 year. Cases were matched 1:1 with patients with benign EBs who did not develop EC (controls) by histology of benign EB (normal endometrium vs. endometrial hyperplasia without atypia), date of EB, age at EB, and length of post-biopsy follow-up. DNA extracted from formalin-fixed paraffin-embedded tissues underwent pyrosequencing to determine percent methylation of promoter region CpGs at 26 loci in 4 genes (ADCYAP1, HAND2, MME, RASSF1A) previously reported as methylated in EC. RESULTS: After pathologic review, 23 matched pairs of cases and controls were identified (14 normal, 9 hyperplasia without atypia per group). Among cases, median time from benign EB to EC was 1 year (range 2 days - 9.2 years). We evaluated 26 CpG sites within 4 genes and found a consistent trend of increasing percentage of methylation from control to case to EC for all CpGs. At the gene-level, mean methylation events of ADCYAP1 and HAND2 in cases were significantly higher than control (p = 0.015 and p = 0.021, respectively). Though the other genes did not reach statistical significance, we observed an increased methylation trend among all genes. Area-under-curve (AUC) calculations (predicting future development of EC in the setting of benign EB) for ADCYAP1 and HAND2 were 0.71 (95% CI 0.55-0.88) and 0.83 (95% CI 0.64-1, respectively). CONCLUSIONS: This proof-of-principle study provides evidence that specific methylation patterns in benign EB correlate with future development of EC.

Genomic alterations in STK11 can predict clinical outcomes in cervical cancer patients.

OBJECTIVE: Cervical cancer is the fourth most common cause of cancer-related deaths in Asian women, due to its poor prognosis. This study aimed to decipher genomic alteration profiles of a cohort of Japanese cervical cancer patients to understand why certain patients benefited from molecular targeted therapies and their prognostic significance. METHODS: During 2008-2018, 154 cervical cancer patients underwent a potentially curative resection procedure at the National Cancer Center Hospital. Genomic DNA samples were analyzed using Ion AmpliSeq™ Cancer Hotspot Panel v2. Alterations in the copy number of PIK3CA, ERBB2, PTEN, and STK11 were detected using the TaqMan assay. HPV-positive results were confirmed by genomic testing and in situ hybridization assay. RESULTS: The frequency of genomic alterations in PIK3CA (36%), STK11 (16%), PTEN (11%), TP53 (11%), and KRAS (8%) was >5%. KRAS mutations were preferentially detected in patients with adenocarcinomas, and the frequency of PIK3CA mutations in patients with squamous cell carcinomas was higher than that in patients with other histological cancer types. HPV-positive results were observed in 139/154 (90.3%) patients, and TP53 mutants were detected in HPV-negative specimens. In this study, the overall survival of patients with genomic alterations in STK11 was worse than in patients with wild-type STK11 (hazard ratio = 10.6, P = 0.0079) and TCGA dataset (hazard ratio = 2.46, P = 0.029). CONCLUSIONS: More than one-third of Japanese cervical cancer patients exhibit mutations targeted by molecular targeted therapies. We have proposed the prognostic value of STK11 genomic alterations.

SFRP1 promotor methylation analysis of FTA card touch-prep samples derived from colonic polyps.

Whatman FTA® cards provide the most reliable method for DNA storage and extraction, however, the literature lacks reports on the epigenetic analysis of FTA card-derived tumor DNA. Therefore, this study aimed at demonstrating that punches from colonic adenoma samples preserved on FTA filter cards are suitable for methylation analysis by real-time methylation-specific PCR (MSP). Genomic DNA was isolated from a total of 40 sporadic colorectal adenoma samples stored on FTA cards for a median of 59.60 (range 48-72) months. After bisulfite treatment, deaminated DNA was analyzed by SYBR Green real-time MSP using primers specific for methylated and unmethylated promotor sequences of the secreted frizzled-related protein 1 (SFRP1) gene. Amplifiable DNA could be isolated from all FTA card punches while SFRP1 promotor methylation was present in 34/40 (85.0%) colorectal adenomas. Our results indicate that genomic DNA isolated from colonic tumor samples preserved on FTA cards is suitable for downstream methylation detection methodologies such as MSP even after prolonged storage periods.

Fast Prototyping Microfluidics: Integrating Droplet Digital Lamp for Absolute Quantification of Cancer Biomarkers.

Microfluidic (MF) advancements have been leveraged toward the development of state-of-the-art platforms for molecular diagnostics, where isothermal amplification schemes allow for further simplification of DNA detection and quantification protocols. The MF integration with loop-mediated isothermal amplification (LAMP) is today the focus of a new generation of chip-based devices for molecular detection, aiming at fast and automated nucleic acid analysis. Here, we combined MF with droplet digital LAMP (ddLAMP) on an all-in-one device that allows for droplet generation, target amplification, and absolute quantification. This multilayer 3D chip was developed in less than 30 minutes by using a low-cost and extremely adaptable production process that exploits direct laser writing technology in "Shrinky-dinks" polystyrene sheets. ddLAMP and target quantification were performed directly on-chip, showing a high correlation between target concentration and positive droplet score. We validated this integrated chip via the amplification of targets ranging from five to 500,000 copies/reaction. Furthermore, on-chip amplification was performed in a 10 µL volume, attaining a limit of detection of five copies/µL under 60 min. This technology was applied to quantify a cancer biomarker, c-MYC, but it can be further extended to any other disease biomarker.

Bioinformatics and DNA-extraction strategies to reliably detect genetic variants from FFPE breast tissue samples.

BACKGROUND: Archived formalin fixed paraffin embedded (FFPE) samples are valuable clinical resources to examine clinically relevant morphology features and also to study genetic changes. However, DNA quality and quantity of FFPE samples are often sub-optimal, and resulting NGS-based genetics variant detections are prone to false positives. Evaluations of wet-lab and bioinformatics approaches are needed to optimize variant detection from FFPE samples. RESULTS: As a pilot study, we designed within-subject triplicate samples of DNA derived from paired FFPE and fresh frozen breast tissues to highlight FFPE-specific artifacts. For FFPE samples, we tested two FFPE DNA extraction methods to determine impact of wet-lab procedures on variant calling: QIAGEN QIAamp DNA Mini Kit ("QA"), and QIAGEN GeneRead DNA FFPE Kit ("QGR"). We also used negative-control (NA12891) and positive control samples (Horizon Discovery Reference Standard FFPE). All DNA sample libraries were prepared for NGS according to the QIAseq Human Breast Cancer Targeted DNA Panel protocol and sequenced on the HiSeq 4000. Variant calling and filtering were performed using QIAGEN Gene Globe Data Portal. Detailed variant concordance comparisons and mutational signature analysis were performed to investigate effects of FFPE samples compared to paired fresh frozen samples, along with different DNA extraction methods. In this study, we found that five times or more variants were called with FFPE samples, compared to their paired fresh-frozen tissue samples even after applying molecular barcoding error-correction and default bioinformatics filtering recommended by the vendor. We also found that QGR as an optimized FFPE-DNA extraction approach leads to much fewer discordant variants between paired fresh frozen and FFPE samples. Approximately 92% of the uniquely called FFPE variants were of low allelic frequency range (< 5%), and collectively shared a "C > T|G > A" mutational signature known to be representative of FFPE artifacts resulting from cytosine deamination. Based on control samples and FFPE-frozen replicates, we derived an effective filtering strategy with associated empirical false-discovery estimates. CONCLUSIONS: Through this study, we demonstrated feasibility of calling and filtering genetic variants from FFPE tissue samples using a combined strategy with molecular barcodes, optimized DNA extraction, and bioinformatics methods incorporating genomics context such as mutational signature and variant allelic frequency.

Preliminary exploration of potential molecular therapeutic targets in recurrent and metastatic parathyroid carcinomas.

Parathyroid carcinoma (PC) is a rare endocrine malignancy. Surgical resection is curative for local lesions, while effective therapies are lacking for recurrent or metastatic PCs. To study whether targeted therapies could be applied in recurrent or metastatic PCs, potential therapeutic targets were identified with next-generation sequencing (NGS). DNA was extracted from formalin-fixed, paraffin-embedded (FFPE) sections from 19 recurrent or metastatic PC samples. A panel of 560 genes was sequenced with NGS to identify genomic alterations at an average sequencing depth of 581×. In total, 190 genomic alterations were identified. Nine PC samples (47%) harbored at least one potentially actionable genomic alteration including in the after genes: ROS1 (5/19; 26%), PTEN (3/19; 16%), TSC1 (2/19; 11%), PIK3CA (1/19; 5%), AKT1 (1/19; 5%), MTOR (1/19; 5%), ERBB2 (1/19; 5%), NTRK1 (1/19; 5%), IDH1 (1/19; 5%) and FGFR3 (1/19; 5%). CDC73 mutations were detected in 9/19 (47%) PC samples. Additional recurrent genomic alterations were identified in MSH2 (15/19; 79%), AR (9/19; 47%), BCR (8/19; 42%), SLC45A3 (6/19; 32%), MAGI1 (5/19; 26%), ZNF521 (4/19; 21%), KMT2C (4/19; 21%) and NOTCH4 (4/19; 21%). Our study identified a relatively high frequency of potentially actionable genomic alterations in PC patients in a Chinese population for the first time. A series of recurrent mutant genes was detected as well. Our study contributes to both the selection of novel targeted therapies for PC and further molecular understanding of this refractory malignancy.

DNA-Containing Exosomes Derived from Cancer Cells Treated with Topotecan Activate a STING-Dependent Pathway and Reinforce Antitumor Immunity.

Danger-associated molecular patterns derived from damaged or dying cells elicit inflammation and potentiate antitumor immune responses. In this article, we show that treatment of breast cancer cells with the antitumor agent topotecan (TPT), an inhibitor of topoisomerase I, induces danger-associated molecular pattern secretion that triggers dendritic cell (DC) activation and cytokine production. TPT administration inhibits tumor growth in tumor-bearing mice, which is accompanied by infiltration of activated DCs and CD8+ T cells. These effects are abrogated in mice lacking STING, an essential molecule in cytosolic DNA-mediated innate immune responses. Furthermore, TPT-treated cancer cells release exosomes that contain DNA that activate DCs via STING signaling. These findings suggest that a STING-dependent pathway drives antitumor immunity by responding to tumor cell-derived DNA.

Staging and prognosis of oropharyngeal carcinoma according to the 8th Edition of the American Joint Committee on Cancer Staging Manual in human papillomavirus infection.

PURPOSE: The aim of this study was to evaluate the 8th edition of the American Joint Committee on Cancer Staging Manual: Head and Neck Section on oropharyngeal squamous cell cancer (OPSCC) and to clarify the relationship between p16 overexpression and the presence of human papillomavirus (HPV) DNA using fresh frozen samples. METHODS: Samples from 100 OPSCC patients were analyzed using polymerase chain reaction (PCR) and p16 immunohistochemistry. RESULTS: Five-year overall survival (OS) was 73.0%, 93.9%, and 62.2% in all, p16-positive (n = 34), and p16-negative (n = 66) cases, respectively. OS tended to be better aligned with stage in the 8th edition than in the 7th edition. The 5-year OS was 96.0% in never or light smokers (< 40 pack-years), and 87.5% in heavy smokers (≥ 40 pack-years) in the p16-positive group, respectively (p = 0.027). HPV infection was found in 100% of p16-positive and 21.2% of p16-negative cases. The p16-positive cases had higher viral load and integrated physical status than the p16-negative cases. Although 1 case with p16 overexpression showed no PCR amplification using consensus primers, PCR amplification was detected using HPV 16 E6-specific primers. CONCLUSIONS: The 8th edition predicts OPSCC prognosis more accurately than the 7th edition and p16-overexpression is an excellent surrogate marker for detecting HPV infection. Although high-risk-type HPV infection was observed in p16-negative cases, it showed no significant effect in survival outcome.

Salvaging the supernatant: next generation cytopathology for solid tumor mutation profiling.

With the expanding role of targeted therapy in patients with solid tumors, pathologists face the daunting task of having to maximize limited volume tissue obtained by fine needle aspiration for a variety of molecular tests. While most molecular studies on fine needle aspiration samples have been reported using cellular material, recent studies have shown that a substantial amount of DNA can be retrieved from the supernatant fluid of aspirate needle rinses after cell pelleting for cytospin or cell block preparations. In routine clinical workflow, the supernatant is discarded; however this fluid may provide a complementary source of DNA for tumor mutational profiling. In this study, we evaluated the post-centrifuged supernatant from 25 malignant and 10 benign fine needle aspiration needle rinses. The mean and median DNA yields from the supernatants were 445 ng and 176.4 ng (range, 15.1-2958 ng), respectively. Next generation sequencing using the Ion AmpliSeq Cancer Hotspot Panel v2 detected somatic mutations in all 25 malignant samples. No mutations were detected in any of the benign samples tested. When available, mutations detected in the supernatant fluid were compared to the next generation sequencing analysis performed on a prior or concurrent surgical specimen from the same patient and showed 100% concordance. In a subset of cases (n = 19) mutations in EGFR, KRAS, BRAF, PIK3CA, and NRAS were successfully confirmed by droplet digital PCR, providing an orthogonal platform for mutation analysis. In summary, in this study we show that post centrifuged supernatants from fine needle aspiration needle rinses can provide a robust substrate for expanded mutation profiling by next generation sequencing, as well as hotspot mutation testing by droplet digital PCR. The ability to detect somatic mutations from otherwise discarded supernatant fluids offers the ability to triage and effectively utilize limited volume fine needle aspiration samples when multiple molecular tests are requested, without the need to re-biopsy for additional tissue samples.

Combined mutation and copy-number variation detection by targeted next-generation sequencing in uveal melanoma.

Uveal melanoma is a highly aggressive cancer of the eye, in which nearly 50% of the patients die from metastasis. It is the most common type of primary eye cancer in adults. Chromosome and mutation status have been shown to correlate with the disease-free survival. Loss of chromosome 3 and inactivating mutations in BAP1, which is located on chromosome 3, are strongly associated with 'high-risk' tumors that metastasize early. Other genes often involved in uveal melanoma are SF3B1 and EIF1AX, which are found to be mutated in intermediate- and low-risk tumors, respectively. To obtain genetic information of all genes in one test, we developed a targeted sequencing method that can detect mutations in uveal melanoma genes and chromosomal anomalies in chromosome 1, 3, and 8. With as little as 10 ng DNA, we obtained enough coverage on all genes to detect mutations, such as substitutions, deletions, and insertions. These results were validated with Sanger sequencing in 28 samples. In >90% of the cases, the BAP1 mutation status corresponded to the BAP1 immunohistochemistry. The results obtained in the Ion Torrent single-nucleotide polymorphism assay were confirmed with several other techniques, such as fluorescence in situ hybridization, multiplex ligation-dependent probe amplification, and Illumina SNP array. By validating our assay in 27 formalin-fixed paraffin-embedded and 43 fresh uveal melanomas, we show that mutations and chromosome status can reliably be obtained using targeted next-generation sequencing. Implementing this technique as a diagnostic pathology application for uveal melanoma will allow prediction of the patients' metastatic risk and potentially assess eligibility for new therapies.

Pancreatic Cancer Cell Fraction Estimation in a DNA Sample.

OBJECTIVE: Pancreatic cancers are characterized by dense stroma. To estimate the degree of interference by coexisting noncancer cells in molecular analyses, we aimed to develop a DNA methylation marker that assesses a cancer cell fraction in DNA samples. METHODS: The microarray data of 22 pancreatic cancer tissues from the The Cancer Genome Atlas database and 9 noncancer tissues were used for genome-wide screening. Thirty-one surgical tumor samples (10 intraductal papillary mucinous neoplasms [IPMNs] and 21 pancreatic cancers), 4 normal, and 26 nontumor samples were used for validation. Gene-specific methylation analysis was conducted by bisulfite pyrosequencing. RESULTS: Genome-wide screening isolated SIM1, MIR129-2, NR1I2, and HOXB-AS4, as specifically methylated in pancreatic cancer cells. Bisulfite pyrosequencing validated that one or more of three genes (SIM1, MIR129-2, and NR1I2) were methylated in 22 (71.0%) tumor samples (8 IPMNs and 14 cancers), and all showed low levels of methylation in 26 (86.7%) normal and nontumor samples. Therefore, the three genes collectively constituted one marker for a pancreatic cancer cell fraction. The cancer cell fraction estimated by the marker was highly correlated with that estimated using the KRAS mutant allele frequency (R = 0.79). CONCLUSION: The DNA methylation marker is useful to estimate the pancreatic cancer cell fraction in DNA samples.

NCCN Guidelines Insights: Colorectal Cancer Screening, Version 1.2018.

The NCCN Guidelines for Colorectal Cancer (CRC) Screening outline various screening modalities as well as recommended screening strategies for individuals at average or increased-risk of developing sporadic CRC. The NCCN panel meets at least annually to review comments from reviewers within their institutions, examine relevant data, and reevaluate and update their recommendations. These NCCN Guidelines Insights summarize 2018 updates to the NCCN Guidelines, with a primary focus on modalities used to screen individuals at average-risk for CRC.

Genetic study of the BRAF gene reveals new variants and high frequency of the V600E mutation among Iranian ameloblastoma patients.

BACKGROUND: Ameloblastoma is a benign, slow-growing and locally invasive tumor. It is one of the most prevalent odontogenic tumors, with an incidence rate of 1% of all oral tumors and approximately 18% of odontogenic tumors. A group of genes have been investigated in patients with ameloblastoma. The BRAF V600E mutation has been implicated as the most common mutation in ameloblastoma. The presence or absence of this mutation has been associated with several clinicopathological properties, including location, age at diagnosis, histology, and prognosis. Although some populations have been investigated so far, little data are available on the Iranian population. The current research was launched to study the BRAF V600E mutation among a cohort of Iranian patients with ameloblastoma. METHODS: In this clinicopathological and molecular biology study, a total of 19 formalin-fixed, paraffin-embedded tissues were studied. DNA extraction was performed, followed by PCR-sequencing of exons 10 and 15 of the BRAF gene to identify mutations. In silico analysis was performed for the identified variants. Results were analyzed by T test, Chi-square, and Fisher's exact test. RESULTS: Totally, 12 of 19 samples (63%) harbored the p. V600E hotspot mutation. In addition, we identified several variants, two of which were novel. The c.1769T>G (p. V590G) and c.1751C>T (p.L584F) as the novel variants showed a possible damaging effect by in silico analysis. No variant was found within exon 10. CONCLUSIONS: Our study confirms the role of BRAF mutations in ameloblastoma in the Iranian patients studied.

Mutational Aberrations Detected in Mucinous Epithelial Ovarian Cancer of Asian Women.

BACKGROUND: Mucinous epithelial ovarian cancers (mEOCs) respond poorly to conventional chemotherapy and have a poor prognosis in advanced stages. The genomic landscape for mEOC in the Asian settings is ill defined. We seek to identify various mutational aberrations present in mEOC and correlate them with clinical outcomes. METHODS: A total of 199 cases of mEOC were identified from a prospectively maintained gynecologic oncology tumor database. DNA was extracted and analyzed for KRAS mutations by using Sanger sequencing. Further MassArray sequencing was performed on 45 samples. Clinicopathologic correlation was performed with the results obtained. FINDINGS: KRAS mutation status was evaluable in 124 cases. Fifty-five percent (68/124) were KRAS negative, whereas 45% (56/124) harbored a KRAS mutation, lower than that in Western populations. Successful ascertainment of both KRAS and HER2 statuses by Sanger sequencing occurred for 105 cases. The proportion of the double-positive subtype (HER2+ and KRAS positive) was 8% (8/105); double-negative subtype (HER2- and KRAS negative), 34% (36/105); and cases with mutation in either KRAS or HER2, 58% (61/105). The KRAS mutation rate was 44%, 50%, and 29% among Chinese, Indians, and Malays, respectively. There was no significant difference in overall survival (P = 0.952) or progression-free survival (P = 0.635) between KRAS-positive and KRAS-negative patients. Similar results were observed for progression-free survival (P = 0.206) and overall survival (P = 0.440) when outcomes were examined between the 4 groups based on KRAS and HER2 mutation. Patients in the double-negative mutation subgroup had higher risk for death/progression compared with patients in the other 3 mutation subgroups. Further MassARRAY multiplexed profiling was performed in patients with sufficient DNA material (n = 45) and yielded KRAS mutations (n = 16), PDGFRA mutations (n = 3), PIK3CA (n = 1) and KIT (n = 1), and HRAS, FGFR, MET, and NRAS (n = 1 each). CONCLUSIONS: Our study provides further knowledge about the mutational aberrations in mEOC in Asian populations. Neither the presence of KRAS mutation nor their correlation with HER2 mutations influenced outcomes.