Evolutionary histories of breast cancer and related clones.

Recent studies have documented frequent evolution of clones carrying common cancer mutations in apparently normal tissues, which are implicated in cancer development1-3. However, our knowledge is still missing with regard to what additional driver events take place in what order, before one or more of these clones in normal tissues ultimately evolve to cancer. Here, using phylogenetic analyses of multiple microdissected samples from both cancer and non-cancer lesions, we show unique evolutionary histories of breast cancers harbouring der(1;16), a common driver alteration found in roughly 20% of breast cancers. The approximate timing of early evolutionary events was estimated from the mutation rate measured in normal epithelial cells. In der(1;16)(+) cancers, the derivative chromosome was acquired from early puberty to late adolescence, followed by the emergence of a common ancestor by the patient's early 30s, from which both cancer and non-cancer clones evolved. Replacing the pre-existing mammary epithelium in the following years, these clones occupied a large area within the premenopausal breast tissues by the time of cancer diagnosis. Evolution of multiple independent cancer founders from the non-cancer ancestors was common, contributing to intratumour heterogeneity. The number of driver events did not correlate with histology, suggesting the role of local microenvironments and/or epigenetic driver events. A similar evolutionary pattern was also observed in another case evolving from an AKT1-mutated founder. Taken together, our findings provide new insight into how breast cancer evolves.

Tobacco smoking and somatic mutations in human bronchial epithelium.

Tobacco smoking causes lung cancer1-3, a process that is driven by more than 60 carcinogens in cigarette smoke that directly damage and mutate DNA4,5. The profound effects of tobacco on the genome of lung cancer cells are well-documented6-10, but equivalent data for normal bronchial cells are lacking. Here we sequenced whole genomes of 632 colonies derived from single bronchial epithelial cells across 16 subjects. Tobacco smoking was the major influence on mutational burden, typically adding from 1,000 to 10,000 mutations per cell; massively increasing the variance both within and between subjects; and generating several distinct mutational signatures of substitutions and of insertions and deletions. A population of cells in individuals with a history of smoking had mutational burdens that were equivalent to those expected for people who had never smoked: these cells had less damage from tobacco-specific mutational processes, were fourfold more frequent in ex-smokers than current smokers and had considerably longer telomeres than their more-mutated counterparts. Driver mutations increased in frequency with age, affecting 4-14% of cells in middle-aged subjects who had never smoked. In current smokers, at least 25% of cells carried driver mutations and 0-6% of cells had two or even three drivers. Thus, tobacco smoking increases mutational burden, cell-to-cell heterogeneity and driver mutations, but quitting promotes replenishment of the bronchial epithelium from mitotically quiescent cells that have avoided tobacco mutagenesis.

Frequent mutations that converge on the NFKBIZ pathway in ulcerative colitis.

Chronic inflammation is accompanied by recurring cycles of tissue destruction and repair and is associated with an increased risk of cancer1-3. However, how such cycles affect the clonal composition of tissues, particularly in terms of cancer development, remains unknown. Here we show that in patients with ulcerative colitis, the inflamed intestine undergoes widespread remodelling by pervasive clones, many of which are positively selected by acquiring mutations that commonly involve the NFKBIZ, TRAF3IP2, ZC3H12A, PIGR and HNRNPF genes and are implicated in the downregulation of IL-17 and other pro-inflammatory signals. Mutational profiles vary substantially between colitis-associated cancer and non-dysplastic tissues in ulcerative colitis, which indicates that there are distinct mechanisms of positive selection in both tissues. In particular, mutations in NFKBIZ are highly prevalent in the epithelium of patients with ulcerative colitis but rarely found in both sporadic and colitis-associated cancer, indicating that NFKBIZ-mutant cells are selected against during colorectal carcinogenesis. In further support of this negative selection, we found that tumour formation was significantly attenuated in Nfkbiz-mutant mice and cell competition was compromised by disruption of NFKBIZ in human colorectal cancer cells. Our results highlight common and discrete mechanisms of clonal selection in inflammatory tissues, which reveal unexpected cancer vulnerabilities that could potentially be exploited for therapeutics in colorectal cancer.

Germ line DDX41 mutations define a unique subtype of myeloid neoplasms.

Germ line DDX41 variants have been implicated in late-onset myeloid neoplasms (MNs). Despite an increasing number of publications, many important features of DDX41-mutated MNs remain to be elucidated. Here we performed a comprehensive characterization of DDX41-mutated MNs, enrolling a total of 346 patients with DDX41 pathogenic/likely-pathogenic (P/LP) germ line variants and/or somatic mutations from 9082 MN patients, together with 525 first-degree relatives of DDX41-mutated and wild-type (WT) patients. P/LP DDX41 germ line variants explained ∼80% of known germ line predisposition to MNs in adults. These risk variants were 10-fold more enriched in Japanese MN cases (n = 4461) compared with the general population of Japan (n = 20 238). This enrichment of DDX41 risk alleles was much more prominent in male than female (20.7 vs 5.0). P/LP DDX41 variants conferred a large risk of developing MNs, which was negligible until 40 years of age but rapidly increased to 49% by 90 years of age. Patients with myelodysplastic syndromes (MDS) along with a DDX41-mutation rapidly progressed to acute myeloid leukemia (AML), which was however, confined to those having truncating variants. Comutation patterns at diagnosis and at progression to AML were substantially different between DDX41-mutated and WT cases, in which none of the comutations affected clinical outcomes. Even TP53 mutations made no exceptions and their dismal effect, including multihit allelic status, on survival was almost completely mitigated by the presence of DDX41 mutations. Finally, outcomes were not affected by the conventional risk stratifications including the revised/molecular International Prognostic Scoring System. Our findings establish that MDS with DDX41-mutation defines a unique subtype of MNs that is distinct from other MNs.

Age-related remodelling of oesophageal epithelia by mutated cancer drivers.

Clonal expansion in aged normal tissues has been implicated in the development of cancer. However, the chronology and risk dependence of the expansion are poorly understood. Here we intensively sequence 682 micro-scale oesophageal samples and show, in physiologically normal oesophageal epithelia, the progressive age-related expansion of clones that carry mutations in driver genes (predominantly NOTCH1), which is substantially accelerated by alcohol consumption and by smoking. Driver-mutated clones emerge multifocally from early childhood and increase their number and size with ageing, and ultimately replace almost the entire oesophageal epithelium in the extremely elderly. Compared with mutations in oesophageal cancer, there is a marked overrepresentation of NOTCH1 and PPM1D mutations in physiologically normal oesophageal epithelia; these mutations can be acquired before late adolescence (as early as early infancy) and significantly increase in number with heavy smoking and drinking. The remodelling of the oesophageal epithelium by driver-mutated clones is an inevitable consequence of normal ageing, which-depending on lifestyle risks-may affect cancer development.

Clonal expansion in normal tissues.

Cancer originates from a single ancestral cell that acquires a driver mutation, which confers a growth or survival advantage, followed by the acquisition of additional driver mutations by descendant cells. Recently, it has become evident that somatic cell mutations accumulate in normal tissues with aging and exposure to environmental factors, such as alcohol, smoking, and UV rays, increases the mutation rate. Clones harboring driver mutations expand with age, leading to tissue remodeling. Lineage analysis of myeloproliferative neoplasms and der(1;16)-positive breast cancer revealed that driver mutations were acquired early in our lives and that the development of cancer takes decades, unveiling the previously unknown early process of cancer development. Evidence that clonal hematopoiesis affects various diseases, including nonneoplastic diseases, highlights the potential role of the identification and functional analysis of mutated clones in unraveling unknown pathologies. In this review, we summarize the recent updates on clonal expansion in normal tissues and the natural history of cancer revealed through lineage analysis of noncancerous and cancerous tissues.

Anti-integrin αvß6 autoantibodies are a potential biomarker for ulcerative colitis-like immune checkpoint inhibitor-induced colitis.

BACKGROUND: No specific biomarker for immune checkpoint inhibitor (ICI)-induced colitis has been established. Previously, we identified anti-integrin αvß6 autoantibodies in >90% of patients with ulcerative colitis (UC). Given that a subset of ICI-induced colitis is similar to UC, we aimed to clarify the relationship between such autoantibodies and ICI-induced colitis. METHODS: Serum anti-integrin αvß6 autoantibody levels were compared between 26 patients with ICI-induced colitis and 157 controls. Endoscopic images of ICI-induced colitis were centrally reviewed. Characteristics of anti-integrin αvß6 autoantibodies in the ICI-induced colitis patients were compared with those of UC patients. RESULTS: Anti-integrin αvß6 autoantibodies were found in 8/26 (30.8%) patients with ICI-induced colitis and 3/157 (1.9%) controls (P < 0.001). Patients with anti-integrin αvß6 autoantibodies had significantly more typical UC endoscopic features than those without the autoantibodies (P < 0.001). Anti-integrin αvß6 autoantibodies in ICI-induced colitis patients were associated with grade ≥3 colitis (P = 0.001) and steroid resistance (P = 0.005). Anti-integrin αvß6 autoantibody titers correlated with ICI-induced colitis disease activity. Anti-integrin αvß6 autoantibodies of ICI-induced colitis exhibited similar characteristics to those of UC. CONCLUSIONS: Anti-integrin αvß6 autoantibodies may serve as potential biomarkers for the diagnosis, classification, risk management, and monitoring the disease activity, of ICI-induced colitis.

Whole-genome landscape of adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATL) is an aggressive neoplasm immunophenotypically resembling regulatory T cells, associated with human T-cell leukemia virus type-1. Here, we performed whole-genome sequencing (WGS) of 150 ATL cases to reveal the overarching landscape of genetic alterations in ATL. We discovered frequent (33%) loss-of-function alterations preferentially targeting the CIC long isoform, which were overlooked by previous exome-centric studies of various cancer types. Long but not short isoform-specific inactivation of Cic selectively increased CD4+CD25+Foxp3+ T cells in vivo. We also found recurrent (13%) 3'-truncations of REL, which induce transcriptional upregulation and generate gain-of-function proteins. More importantly, REL truncations are also common in diffuse large B-cell lymphoma, especially in germinal center B-cell-like subtype (12%). In the non-coding genome, we identified recurrent mutations in regulatory elements, particularly splice sites, of several driver genes. In addition, we characterized the different mutational processes operative in clustered hypermutation sites within and outside immunoglobulin/T-cell receptor genes and identified the mutational enrichment at the binding sites of host and viral transcription factors, suggesting their activities in ATL. By combining the analyses for coding and noncoding mutations, structural variations, and copy number alterations, we discovered 56 recurrently altered driver genes, including 11 novel ones. Finally, ATL cases were classified into 2 molecular groups with distinct clinical and genetic characteristics based on the driver alteration profile. Our findings not only help to improve diagnostic and therapeutic strategies in ATL, but also provide insights into T-cell biology and have implications for genome-wide cancer driver discovery.

On the origin of gastric tumours: analysis of a case with intramucosal gastric carcinoma and oxyntic gland adenoma.

Most gastric cancers develop in inflamed gastric mucosa due to Helicobacter pylori infection, typically with metaplastic changes. However, the origins of gastric cancer remain unknown. Here, we present a case of intramucosal gastric carcinoma (IGC) and oxyntic gland adenoma (OGA) derived from spasmolytic polypeptide-expressing metaplasia (SPEM). Early gastric cancer adjacent to a polyp was found in the upper corpus of a 71-year-old woman without H. pylori infection and was endoscopically resected. Histological examination showed IGC and OGA, both of which had predominant MUC6 expression. Interestingly, gastric glands with enriched MUC6-positive mucous cells, referred to as SPEM, expanded between them. Whole-exome sequencing analysis revealed a truncating KRAS(G12D) mutation in IGC, OGA, and SPEM. In addition, TP53 and CDKN2A mutations and a loss of chromosome 17p were found in the IGC, whereas a GNAS mutation was observed in the OGA. These results indicated that IGC and OGA originated from the KRAS-mutated SPEM. © 2023 The Pathological Society of Great Britain and Ireland.

Blockage of retinoic acid signaling via RARγ suppressed the proliferation of pancreatic cancer cells by arresting the cell cycle progression of the G1-S phase.

BACKGROUND: Our study and several studies have reported that in some cancers, including pancreatic ductal adenocarcinoma (PDAC), the expression of squamous lineage markers, such as esophagus-tissue-specific genes, correlated with a poor prognosis. However, the mechanism by which the acquisition of squamous lineage phenotypes leads to a poor prognosis remains unclear. We previously reported that retinoic acid signaling via retinoic acid receptor γ (RARγ signaling) determines the differentiation lineage into the esophageal squamous epithelium. These findings hypothesized that the activation of RARγ signaling contributed to acquiring squamous lineage phenotypes and malignant behavior in PDAC. METHODS: This study utilized public databases and immunostaining of surgical specimens to examine RARγ expression in PDAC. We evaluated the function of RARγ signaling by inhibitors and siRNA knockdown using a PDAC cell line and patient-derived PDAC organoids. The mechanism of the tumor-suppressive effects by blocking RARγ signaling was examined by a cell cycle analysis, apoptosis assays, RNA sequencing and Western blotting. RESULTS: RARγ expression in pancreatic intraepithelial neoplasia (PanIN) and PDAC was higher than that in the normal pancreatic duct. Its expression correlated with a poor patient prognosis in PDAC. In PDAC cell lines, blockade of RARγ signaling suppressed cell proliferation by inducing cell cycle arrest in the G1 phase without causing apoptosis. We demonstrated that blocking RARγ signaling upregulated p21 and p27 and downregulated many cell cycle genes, including cyclin-dependent kinase 2 (CDK2), CDK4 and CDK6. Furthermore, using patient-derived PDAC organoids, we confirmed the tumor-suppressive effect of RARγ inhibition and indicated the synergistic effects of RARγ inhibition with gemcitabine. CONCLUSIONS: This study clarified the function of RARγ signaling in PDAC progression and demonstrated the tumor-suppressive effect of selective blockade of RARγ signaling against PDAC. These results suggest that RARγ signaling might be a new therapeutic target for PDAC.

A case of vasoactive intestinal peptide-secreting tumor (VIPoma) arising from MEN1 inactivation which recurred 15 years after the initial resection.

Vasoactive intestinal peptide-secreting tumors (VIPomas) are extremely rare functional pancreatic neuroendocrine neoplasms (p-NENs) characterized by watery diarrhea, hypokalemia, and achlorhydria. Here, we report the case of a 51-year-old female patient with VIPoma that recurred after a long-term disease-free interval. This patient had been asymptomatic for approximately 15 years after the initial curative surgery for pancreatic VIPoma, with no metastasis. The patient underwent a second curative surgery for the locally recurrent VIPoma. Whole-exome sequencing of the resected tumor revealed a somatic mutation in MEN1, which is reportedly responsible not only for multiple endocrine neoplasia type 1 (MEN1) syndrome but also sporadic p-NENs. Symptoms were controlled with lanreotide before and after surgery. The patient is alive with no relapse following 14 months after surgery. This case demonstrates the importance of long-term observation of patients with VIPoma.

The landscape of genetic aberrations in myxofibrosarcoma.

Myxofibrosarcoma (MFS) is a rare subtype of sarcoma, whose genetic basis is poorly understood. We analyzed 69 MFS cases using whole-genome (WGS), whole-exome (WES) and/or targeted-sequencing (TS). Newly sequenced genomic data were combined with additional deposited 116 MFS samples. WGS identified a high number of structural variations (SVs) per tumor most frequently affecting the TP53 and RB1 loci, 40% of tumors showed a BRCAness-associated mutation signature, and evidence of chromothripsis was found in all cases. Most frequently mutated/copy number altered genes affected known disease drivers such as TP53 (56.2%), CDKN2A/B (29.7%), RB1 (27.0%), ATRX (19.5%) and HDLBP (18.9%). Several previously unappreciated genetic aberrations including MUC17, FLG and ZNF780A were identified in more than 20% of patients. Longitudinal analysis of paired diagnosis and relapse time points revealed a 1.2-fold mutation number increase accompanied with substantial changes in clonal composition over time. Our study highlights the genetic complexity underlying sarcomagenesis of MFS.

Identification of an Anti-Integrin αvß6 Autoantibody in Patients With Ulcerative Colitis.

BACKGROUND AND AIMS: Ulcerative colitis is the most frequent type of inflammatory bowel disease and is characterized by colonic epithelial cell damage. Although involvement of autoimmunity has been suggested in ulcerative colitis, specific autoantigens/antibodies have yet to be elucidated. METHODS: Using 23 recombinant integrin proteins, we performed enzyme-linked immunosorbent assays on sera from patients with ulcerative colitis and controls. Integrin expression and IgG binding in the colon tissues of patients with ulcerative colitis and controls were examined using immunofluorescence and coimmunoprecipitation, respectively. The blocking activity of autoantibodies was examined using solid-phase binding and cell adhesion assays. RESULTS: Screening revealed that patients with ulcerative colitis had IgG antibodies against integrin αvß6. In the training and validation groups, 103 of 112 (92.0%) patients with ulcerative colitis and only 8 of 155 (5.2%) controls had anti-integrin αvß6 antibodies (P < .001), resulting in a sensitivity of 92.0% and a specificity of 94.8% for diagnosing ulcerative colitis. Anti-integrin αvß6 antibody titers coincided with ulcerative colitis disease activity, and IgG1 was the major subclass. Patient IgG bound to the integrin αvß6 expressed on colonic epithelial cells. Moreover, IgG of patients with ulcerative colitis blocked integrin αvß6-fibronectin binding through an RGD (Arg-Gly-Asp) tripeptide motif and inhibited cell adhesion. CONCLUSIONS: A significant majority of patients with ulcerative colitis had autoantibodies against integrin αvß6, which may serve as a potential diagnostic biomarker with high sensitivity and specificity.

A novel SREBF1::NACC1 gene fusion in an unclassifiable intracranial tumour.

A 39-year-old man had an intracranial tumour without infiltration into the surrounding cerebral tissue. The tumour recurred seven times in 11 years but maintained a well-demarcated character. Histopathological examination of the 4th surgical specimens showed nests of tumour cells surrounding small blood vessels. The tumour cells harboured amphophilic cytoplasm and small round nuclei with fine chromatin, and perinuclear haloes and clear borders were frequently observed, which was unclassifiable histology. By the Deutsches Krebsforschungszentrum methylation classifier, the tumour was not classified into any of the methylation classes. mRNA sequencing identified a novel SREBF1::NACC1 gene fusion. This intracranial tumour could be a novel tumour entity with NACC1 rearrangement showing characteristic histological and diagnostic imaging findings.

Aberrant PD-L1 expression through 3'-UTR disruption in multiple cancers.

Successful treatment of many patients with advanced cancer using antibodies against programmed cell death 1 (PD-1; also known as PDCD1) and its ligand (PD-L1; also known as CD274) has highlighted the critical importance of PD-1/PD-L1-mediated immune escape in cancer development. However, the genetic basis for the immune escape has not been fully elucidated, with the exception of elevated PD-L1 expression by gene amplification and utilization of an ectopic promoter by translocation, as reported in Hodgkin and other B-cell lymphomas, as well as stomach adenocarcinoma. Here we show a unique genetic mechanism of immune escape caused by structural variations (SVs) commonly disrupting the 3' region of the PD-L1 gene. Widely affecting multiple common human cancer types, including adult T-cell leukaemia/lymphoma (27%), diffuse large B-cell lymphoma (8%), and stomach adenocarcinoma (2%), these SVs invariably lead to a marked elevation of aberrant PD-L1 transcripts that are stabilized by truncation of the 3'-untranslated region (UTR). Disruption of the Pd-l1 3'-UTR in mice enables immune evasion of EG7-OVA tumour cells with elevated Pd-l1 expression in vivo, which is effectively inhibited by Pd-1/Pd-l1 blockade, supporting the role of relevant SVs in clonal selection through immune evasion. Our findings not only unmask a novel regulatory mechanism of PD-L1 expression, but also suggest that PD-L1 3'-UTR disruption could serve as a genetic marker to identify cancers that actively evade anti-tumour immunity through PD-L1 overexpression.

A novel technique for mapping biopsy of bile duct cancer.

BACKGROUND : Accurate preoperative assessment of the longitudinal extension of perihilar cholangiocarcinoma (PHCC) is essential for treatment planning. Mapping biopsies for PHCC remain challenging owing to technical difficulties and insufficient sample amounts. The aim of this study was to investigate the usefulness of a novel technique for mapping biopsies of PHCC. METHODS : Our novel method focused on a biliary stent delivery system for mapping biopsies. Fifty patients with PHCC undergoing endoscopic transpapillary mapping biopsy using the novel method were reviewed from August 2015 to June 2019. RESULTS : The median number of biopsy samples was six (range 1 - 17), and the rate of adequate sampling was 91.4 % (266 /291). Biopsy from the intrahepatic bile duct was possible in 82.0 % of patients (41 /50), and negative margins were confirmed in the resected specimens from 34 /39 patients who underwent surgery (87.2 %). None of the patients had post-endoscopic retrograde cholangiopancreatography pancreatitis. CONCLUSIONS : With our novel method, accurate assessment of the longitudinal extension of PHCC might be expected with minimal trauma to the duodenal papilla.

Indolent feature of Helicobacter pylori-uninfected intramucosal signet ring cell carcinomas with CDH1 mutations.

BACKGROUND: In Helicobacter pylori (Hp)-uninfected individuals, diffuse-type gastric cancer (DGC) was reported as the most common type of cancer. However, the carcinogenic mechanism of Hp-uninfected sporadic DGC is largely unknown. METHODS: We performed whole-exome sequencing of Hp-uninfected DGCs and Hp-uninfected normal gastric mucosa. For advanced DGCs, external datasets were also analyzed. RESULTS: Eighteen patients (aged 29-78 years) with DGCs and nine normal subjects (28-77 years) were examined. The mutation burden in intramucosal DGCs (10-66 mutations per exome) from individuals aged 29-73 years was not very different from that in the normal gastric glands, which showed a constant mutation accumulation rate (0.33 mutations/exome/year). Unbiased dN/dS analysis showed that CDH1 somatic mutation was a driver mutation for intramucosal DGC. CDH1 mutation was more frequent in intramucosal DGCs (67%) than in advanced DGCs (27%). In contrast, TP53 mutation was more frequent in advanced DGCs (52%) than in intramucosal DGCs (0%). This discrepancy in mutations suggests that CDH1-mutated intramucosal DGCs make a relatively small contribution to advanced DGC formation. Among the 16 intramucosal DGCs (median size, 6.5 mm), 15 DGCs were pure signet ring cell carcinoma (SRCC) with reduced E-cadherin expression and a low proliferative capacity (median Ki-67 index, 2.4%). Five SRCCs reviewed endoscopically over 2-5 years showed no progression. CONCLUSIONS: Impaired E-cadherin function due to CDH1 mutation was considered as an early carcinogenic event of Hp-uninfected intramucosal SRCC. Genetic and clinical analyses suggest that Hp-uninfected intramucosal SRCCs may be less likely to develop into advanced DGCs.

[How Does Aging Contribute to Cancer?]

Advances in sequencing technology have been reported to show cancer driver mutations with aging in a variety of normal tissues at very small clone sizes. In the normal esophagus, prior to carcinogenesis, clones that had acquired driver mutations in esophageal cancer, mainly NOTCH1 mutations, during early life appeared multi-centrically. With aging, the number of driver mutations increased and the clones expanded. In the elderly, most of the normal esophagus was replaced by clones with driver mutations. In contrast, in normal colorectal epithelium, about 1% of crypts contain driver mutations even in the 50s. In normal hepatocytes, age-related mutations are rarely detected. These results suggest that the frequency of detection of driver mutations in normal tissues varies greatly among tissues. The panorama of aging and cancer remains veiled.

Genetic abnormalities in myelodysplasia and secondary acute myeloid leukemia: impact on outcome of stem cell transplantation.

Genetic alterations, including mutations and copy-number alterations, are central to the pathogenesis of myelodysplastic syndromes and related diseases (myelodysplasia), but their roles in allogeneic stem cell transplantation have not fully been studied in a large cohort of patients. We enrolled 797 patients who had been diagnosed with myelodysplasia at initial presentation and received transplantation via the Japan Marrow Donor Program. Targeted-capture sequencing was performed to identify mutations in 69 genes, together with copy-number alterations, whose effects on transplantation outcomes were investigated. We identified 1776 mutations and 927 abnormal copy segments among 617 patients (77.4%). In multivariate modeling using Cox proportional-hazards regression, genetic factors explained 30% of the total hazards for overall survival; clinical characteristics accounted for 70% of risk. TP53 and RAS-pathway mutations, together with complex karyotype (CK) as detected by conventional cytogenetics and/or sequencing-based analysis, negatively affected posttransplant survival independently of clinical factors. Regardless of disease subtype, TP53-mutated patients with CK were characterized by unique genetic features and associated with an extremely poor survival with frequent early relapse, whereas outcomes were substantially better in TP53-mutated patients without CK. By contrast, the effects of RAS-pathway mutations depended on disease subtype and were confined to myelodysplastic/myeloproliferative neoplasms (MDS/MPNs). Our results suggest that TP53 and RAS-pathway mutations predicted a dismal prognosis, when associated with CK and MDS/MPNs, respectively. However, for patients with mutated TP53 or CK alone, long-term survival could be obtained with transplantation. Clinical sequencing provides vital information for accurate prognostication in transplantation.

Genetic analysis of a case of Helicobacter pylori-uninfected intramucosal gastric cancer in a family with hereditary diffuse gastric cancer.

Germline mutations in CDH1, encoding E-cadherin, are known to be the causative mechanism of hereditary diffuse gastric cancer (HDGC). We encountered two cases of gastric cancer in a Japanese family with HDGC. A 28-year-old man (Case 1) died of advanced gastric cancer. His younger sister aged 27 (Case 2) was diagnosed with intramucosal signet ring cell carcinoma (SRCC). Both had identical germline CDH1 mutations, but Case 1 was positive for Helicobacter pylori infection, whereas Case 2 was negative. Case 2 underwent total gastrectomy. Whole-exome sequencing of an intramucosal SRCC in Case 2 revealed seven somatic mutations including one in CDH1. The six non-CDH1 mutations were classified as non-driver mutations. Decreased expression of E-cadherin in intramucosal SRCC was confirmed by immunohistochemistry. Our report demonstrated that CDH1 mutation was the only active driver mutation in Helicobacter pylori-uninfected intramucosal SRCC.