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• Comprehensive molecular and clinicopathological profiling of lung adenocarcinoma in Japanese never or light smokers

  Studies have yet to characterize the differences in molecular profiles of lung adenocarcinoma (LUAD) among divergent ethnic groups. Herein, we conducted comprehensive molecular profiling of LUAD in never or light smokers from Asia in order to discover novel targetable mutations and prognostic biomarkers of this distinct disease entity. Methods: We analyzed 996 cases of Asian LUAD, and performed whole-exome sequencing and/or RNA-seq in 125 cases of Asian LUAD negative for the driver oncogenes defined by conventional laboratory testing. We also investigated the clinical and pathological characteristics among the 996 cases. Results: Driver oncogenes were identified in 88 cases (70.4%) with specific hotspot mutations differing from those in The Cancer Genome Atlas (TCGA) study. Clustering based on mRNA expression profiles, but not genetic mutational ones, could predict patient prognosis. The risk score generated by the expression of a three-gene set was a strong prognostic marker for overall survival and progression-free survival in our cohort, and was further validated using TCGA cohort. Among the 996 cases, each driver alteration is distributed across all histological subtypes. Adenocarcinoma in situ was identified to harbor driver mutations, suggesting that these alterations are early events in the pathogenesis of LUAD. This study indicates the value of applying gene expression profiling for predicting the prognosis after a surgical operation, and that the identification of actionable mutations is important for optimizing targeted drugs in Japanese LUAD.

  Study JGAS000215

• Immuno-genomic Profiling of Biopsy Specimens Predicts Neoadjuvant Chemotherapy Response in Esophageal Squamous Cell Carcinoma

  Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive cancers and is primarily treated with platinum-based neoadjuvant chemotherapy (NAC). Some ESCCs respond well to NAC. However, biomarkers to predict NAC sensitivity and their response mechanism in ESCC remain unclear. We introduce a model by machine learning and validated its potential to predict the NAC response in ESCC. To create this model, we performed whole genome sequencing and RNA-seq analysis on totally 141 ESCC biopsy specimens before NAC treatment and analyzed their immuno-genomic features and association with NAC response. Neutrophils infiltration could play an important role in ESCC response to NAC. We also demonstrated that specific copy number alterations and copy number signatures in the ESCC genome were significantly associated with NAC response. The interactions between the tumor genome and immune features of ESCC are likely to be a new indicator of therapeutic capability and a new therapeutic target for ESCC, and machine learning prediction for NAC response is useful.

  Study JGAS000535

• Target sequencing of 27 cancer-predisposing genes in Japanese pancreatic cancer patients

  Background: National Comprehensive Cancer Network (NCCN) recently recommended germline genetic testing for all pancreatic cancer patients. However, the genes targeted by genetic testing and the feasibility of selecting patients likely to carry pathogenic variants have not been sufficiently verified. The purpose of this study was to genetically characterize Japanese patients and examine whether the current guideline is applicable in this population. Methods: Using targeted sequencing, we analyzed the coding regions of 27 cancer-predisposing genes in 1,005 pancreatic cancer patients and 23,705 controls in Japan. We compared the pathogenic variant frequency between cases and controls and documented the demographic and clinical characteristics of carrier patients. We then examined if it was possible to use machine learning to predict carrier status based on those characteristics. Findings: We identified 205 pathogenic variants across the 27 genes. Pathogenic variants in BRCA2, ATM, and BRCA1 were significantly associated with pancreatic cancer. Characteristics associated with carrier status were inconsistent with previous investigations. Machine learning classifiers had a low performance in determining the carrier status of pancreatic cancer patients, while the same classifiers, when applied to breast cancer data as a positive control, had a higher performance that was comparable to that of the NCCN guideline. Interpretation: Our findings support the clinical significance of multigene panel testing for pancreatic cancer and indicate that at least 3.4% of Japanese patients may respond to poly (ADP ribose) polymerase inhibitor treatments. The difficulty in predicting carrier status suggests that offering germline genetic testing for all pancreatic cancer patients is reasonable.

  Study JGAS000327

• Defined Lifestyle and Germline Factors Predispose Asian Populations to Gastric Cancer

  Gastric cancer (GC) is one of the leading causes of cancer mortality throughout the world, with the highest incidence in east-Asia. Although the somatic genetics of GC has extensively been characterized by recent advances in cancer genome sequencing, the germline and environmental effects on GC and their ethnic differences have poorly been understood. Here, we performed genomic scale trans-ethnic analysis of 531 GC cases (319 Asian and 212 non-Asians), by integrating east-Asian and public GC datasets. There is one distinct GC subclass with clear alcohol-associated mutation signature and strong Asian specificity, and almost all the cases in the subclass are attributable to alcohol intake behavior, smoking habit, and Asian-specific ALDH2 defective allele. Alcohol-related GCs have low mutation burden and a characteristic immune profile of increased B-cell infiltration into the tumor area in relation to cancer cell-intrinsic CXCL13 chemokine expression. In addition to germline variants of genes involved in BRCA pathways, we found frequent (7.4%) germline CDH1 variants among Japanese GCs. Most of them were attributed to a few recurrent SNVs shared by both Japanese and Koreans, suggesting the existence of common ancestral events and widespread distributions of these pathogenic variants among east-Asian populations. Specifically, approximately one-fifth of diffuse-type GCs were attributable to the combination of alcohol intake and defective-ALDH2 allele or to germline CDH1 variants. These results revealed uncharacterized impacts of germline variants and their interplays with lifestyles in the high incidence areas.

  Study JGAS000228

• Analysis of mutational and proteomic heterogeneity of gastric cancer to monitor post-treatment tumor burden using circulating tumor DNA

  It remains unclear whether complete spectrum of tumor heterogeneity is reflected in circulating tumor DNA (ctDNA). Here, we performed multi-regional target sequencing of primary tumors from 10 patients who underwent surgical resection for gastric cancer. A total of 126 non-synonymous mutations were identified from 30 samples from 10 tumors. Of these, 16 (12.7%) were likely mutations that occurred early in tumor development (i.e., present in all three regions) and were designated founder mutations. Among those validated with highly sensitive digital PCR (dPCR), 93% of non-founder mutations were found in all three regions. Variant allele frequencies (VAFs) of founder mutations were significantly higher than those of non-founder mutations. Phylogenetic analysis demonstrated that five of eight tumors (62.5%, excluding two hypermutator) had at least one identifiable truncal/founder mutation. These findings led us to prioritize founder mutations for ctDNA detection with individually-designed primer/probe sets for dPCR. Marked proteomic diversity was present across the tumor regions both within and between patients independent of mutational status. In preoperative plasma, the average ctDNA VAF of founder mutations was significantly higher than that of non-founder mutations (p = 0.039). Our present data demonstrated that high VAF mutations in the tumor likely represent founder or truncal mutations. However, mutation patterns alone appear insufficient to predict protein heterogeneity. These results suggest that, in practice, mutations having high VAF identified without multi-regional sequencing may be useful for ctDNA monitoring but are inadequate to fully predict proteomic heterogeneity of the tumor.

  Study JGAS000231

• Identification of genetic mutations characteristic for recurrence and metastasis of colon and rectal cancer.

  We collected the cancerous tissues of the primary and recurrence tumors from the same patient with recurrent / metastatic colorectal cancer, and the purpose of this study is to find the characteristics of recurrent / metastatic colorectal cancers by carrying out a "molecular profiling", mainly the exome sequence analysis of these tissues.

  Study JGAS000091

• Identification of genetic mutations characteristic for recurrence and metastasis of gastric cancer.

  We collected the cancerous tissues of the primary and recurrence tumors from the same patient with recurrent / metastatic gastric cancer, and the purpose of this study is to find the characteristics of recurrent / metastatic gastric cancers by carrying out a "molecular profiling", mainly the exome sequence analysis of these tissues.

  Study JGAS000086

• Sequencing cancer mutations in various types of lung cancer using the long-read, portable sequencer

  In this study, we used a long-read and portable sequencer MinION to identify cancer mutations in lung adenocarcinoma cells. We performed cDNA amplicon sequencing for various types of mutations such as point mutations in EGFR and KRAS and oncogenic fusion transcripts in ALK and RET. Using the long reads of MinION, we also conducted mutation phasing of EGFR TKI-sensitive and resistant mutations, which would provide useful information to next thrapeutic approaches for cancers. We applied this method to identify mutation genotypes of eight clinical samples from Japanese lung adenocarcinomas. This method could provide new sequencing-based diagnostic approaches for lung cancers. Additinally we also performed cancer mutation identification of risk-dependent unique samples. Usual interstitial pneumonia (UIP) is a risk factor for lung carcinogenesis. This study was performed to characterize mutagenesis and mutational target genes underlying lung carcinogenesis in patients with UIP.We performed whole exome sequencing of lung adenocarcinoma with usual interstitial pneumonia.

  Study JGAS000065

• Identification of genetic mutations characteristic for recurrence of serous ovarian cancer.

  Establishment of novel therapeutic strategy to overcome intractable cancer by molecular profiling of serous ovarian cancer

  Study JGAS000104

• Genome and gene analysis of gastrointestinal cancer and elucidation of its clinicopathological significance

  Cancer develops through the accumulation of genetic and epigenetic aberrations. To identify sequential molecular alterations that occur during the development of hepatocellular carcinoma (HCC), we molecularly compared 52 early and 108 overt HCC samples by genome sequencing. Gene mutations in the p53/RB1 pathway, WNT pathway, MLLs, SWI/SNF complexes, and AKT/PI3K pathway were common in HCC. In the early phase of all entities, TERT was the most frequently upregulated gene owing to diverse mechanisms. Despite frequent somatic mutations in driver genes, including CTNNB1 and TP53, early HCC was a separate molecular entity from overt HCC as each had a distinct expression profile. Notably, WNT target genes were not activated in early HCC, regardless of CTNNB1 mutation status, because ?-catenin did not translocate into the nucleus due to the E-Cadherin/?-catenin complex at the membrane. Conversely, WNT targets were definitively upregulated in overt HCC with CTNNB1 mutation associated with downregulation of CDH1 and hypomethylation of CpG islands in the target genes. Similarly, cell cycle genes downstream of the p53/RB pathway were upregulated only in overt HCC with TP53 and/or RB1 gene mutations associated with chromosomal deletion of 4q and/or 16q. Differing from the expression profile, HCC was epigenetically distinguished into four subclasses: normal-like methylation, global-hypomethylation (favorable prognosis), stem-like methylation (poor prognosis), and CpG island methylation. These methylation statuses were globally maintained through HCC progression. Taken together, additional molecular events besides driver gene mutations cooperatively contribute to transcriptional activation of downstream targets as HCC progresses, according to the methylation status of the associated genes.

  Study JGAS000233