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Abstract Background Double‐flap technique (DFT) is a reconstruction procedure after proximal gastrectomy (PG). We previously reported a multi‐center, retrospective study in which the incidence of reflux esophagitis (RE) (Los Angeles Classification ≥Grade B [LA‐B]) 1 year after surgery was 6.0%. There have been many reports, but all of them were retrospective. Thus, a multi‐center, prospective study was conducted. Methods Laparoscopic PG + DFT was performed for cT1N0 upper gastric cancer patients. The primary endpoint was the incidence of RE (≥LA‐B) 1 year after surgery. The planned sample size was 40, based on an estimated incidence of 6.0% and an upper threshold of 20%. Results Forty patients were recruited, and 39, excluding one with conversion to total gastrectomy, received protocol treatment. Anastomotic leakage (Clavien–Dindo ≥Grade III) was observed in one patient (2.6%). In 38 patients, excluding one case of postoperative mortality, RE (≥LA‐B) was observed in two patients (5.3%) 1 year after surgery, and the upper limit of the 95% confidence interval was 17.3%, lower than the 20% threshold. Anastomotic stricture requiring dilatation was observed in two patients (5.3%). One year after surgery, body weight change was 88.9 ± 7.0%, and PNI

Vaginoplasty is a gender-affirming surgery (GAS) for transwomen that laid its foundation in the 1950s and continues to be widely practiced worldwide. We present here a case of a 70-year-old transwoman who underwent lower anterior resection for rectal cancer 12 years after vaginoplasty. The preoperative diagnosis was rectal cancer (Rb-Ra, type 2, cT2N0M0, stage 1). All imaging studies showed a cord-like structure between the prostate and the anterior wall of the rectum, which was thought to be the neovagina. Careful dissection of the anterior rectal wall was required because the distance between the neovagina and the rectum was only 1.5 mm. The role of hormonal therapy and GAS in cancer development in transwomen is unclear. It is important to have regular check-ups for malignancies in patients who have undergone GAS, and if surgical procedures are needed, they should be treated by physicians who are familiar with the procedure.

Immune checkpoint inhibitors, including anti-programmed cell death 1 (PD-1) antibody, provide improved clinical outcome in certain cancers. However, pancreatic ductal adenocarcinoma (PDAC) is refractory to PD-1 blockade therapy due to poor immune response. Oncolytic virotherapy is a novel approach for inducing immunogenic cell death (ICD). We demonstrated the therapeutic potential of p53-expressing telomerase-specific oncolytic adenovirus OBP-702 to induce ICD and anti-tumor immune responses in human PDAC cells with different p53 status (Capan-2, PK-59, PK-45H, Capan-1, MIA PaCa-2, BxPC-3) and murine PDAC cells (PAN02). OBP-702 significantly enhanced ICD with secretion of extracellular adenosine triphosphate and high-mobility group box protein B1 by inducing p53-mediated apoptosis and autophagy. OBP-702 significantly promoted the tumor infiltration of CD8+ T cells and the anti-tumor efficacy of PD-1 blockade in a subcutaneous PAN02 syngeneic tumor model. Our results suggest that oncolytic adenovirus-mediated p53 overexpression augments ICD and the efficacy of PD-1 blockade therapy against cold PDAC tumors. Further in vivo experiments would be warranted to evaluate the survival benefit of tumor-bearing mice in combination therapy with OBP-702 and PD-1 blockade.

Abstract Background Remnant gastric cancer (RGC) has been increasing for various reasons such as a longer life span, medical progress, and others. It generally has a poor prognosis, and its mechanism of occurrence is unknown. The purpose of this study was to evaluate the clinicopathological features of and clarify the oncological features of RGC. Methods Between January 2002 and January 2017, 39 patients with RGC following distal gastrectomy underwent curative surgical resection at the Okayama University Hospital; their medical records and immunohistochemically stained extracted specimens were used for retrospective analysis. Results On univariate analysis, initial gastric disease, pathological lymph node metastasis, and pathological stage were the significant factors associated with poor overall survival (p=0.014, 0.0061, and 0.016, respectively). Multivariate analysis of these 3 factors showed that only initial gastric disease caused by malignant disease was an independent factor associated with a poor prognosis (p=0.014, hazard ratio: 4.2, 95% confidence interval: 1.3–13.0). In addition, tumor-infiltrating CD8+ T cells expression was higher in the benign disease group than in the malignant group (p=0.046). Conclusions Initial gastrectomy caused by malignant disease was an independent poor prognostic factor of RGC, and as one of the causes, lower level of tumor-infiltrating CD8+ T cells in RGC may involve in.

Abstract Cancer-associated fibroblasts (CAFs) play a significant role in tumor progression within the tumor microenvironment. Previously, we used near-infrared photoimmunotherapy (NIR-PIT), a next-generation cancer cell-targeted phototherapy, to establish CAF-targeted NIR-PIT. In this study, we investigated whether dual-targeted NIR-PIT, targeting cancer cells and CAFs, could be a therapeutic strategy. A total of 132 cases of esophageal cancer were analyzed for epidermal growth factor receptor (EGFR), human epidermal growth factor 2 (HER2), and fibroblast activation protein (FAP) expression using immunohistochemistry. Human esophageal cancer cells and CAFs were co-cultured and treated with single- or dual-targeted NIR-PIT in vitro. These cells were co-inoculated into BALB/c-nu/nu mice and the tumors were treated with single-targeted NIR-PIT or dual-targeted NIR-PIT in vivo. Survival analysis showed FAP- or EGFR-high patients had worse survival than patients with low expression of FAP or EGFR (log-rank, P

Abstract Most cases of colorectal cancers (CRCs) are microsatellite stable (MSS), which frequently demonstrate lower response rates to immune checkpoint inhibitors (ICIs). RNA editing produces neoantigens by altering amino acid sequences. In this study, RNA editing was induced artificially by chemoradiation therapy (CRT) to generate neoantigens in MSS CRCs. Altogether, 543 CRC specimens were systematically analyzed, and the expression pattern of ADAR1 was investigated. In vitro and in vivo experiments were also performed. The RNA editing enzyme ADAR1 was upregulated in microsatellite instability–high CRCs, leading to their high affinity for ICIs. Although ADAR1 expression was low in MSS CRC, CRT including oxaliplatin (OX) treatment upregulated RNA editing levels by inducing ADAR1. Immunohistochemistry analyses showed the upregulation of ADAR1 in patients with CRC treated with CAPOX (capecitabine + OX) radiation therapy relative to ADAR1 expression in patients with CRC treated only by surgery (p

Cancer-associated fibroblasts (CAFs) in the tumor microenvironment are associated with the establishment and progression of peritoneal metastasis. This study investigated the efficacy of replicative oncolytic adenovirus-mediated p53 gene therapy (OBP-702) against CAFs and peritoneal metastasis of gastric cancer (GC). Higher CAF expression in the primary tumor was associated with poor prognosis of GC, and higher CAF expression was also observed with peritoneal metastasis in immunohistochemical analysis of clinical samples. And, we found transcriptional alteration of p53 in CAFs relative to normal gastric fibroblasts (NGFs). CAFs increased the secretion of cancer-promoting cytokines, including interleukin-6, and gained resistance to chemotherapy relative to NGFs. OBP-702 showed cytotoxicity to both GC cells and CAFs but not to NGFs. Overexpression of wild-type p53 by OBP-702 infection caused apoptosis and autophagy of CAFs and decreased the secretion of cancer-promoting cytokines by CAFs. Combination therapy using intraperitoneal administration of OBP-702 and paclitaxel synergistically inhibited the tumor growth of peritoneal metastases and decreased CAFs in peritoneal metastases. OBP-702, a replicative oncolytic adenovirus-mediated p53 gene therapy, offers a promising biological therapeutic strategy for peritoneal metastasis, modulating CAFs in addition to achieving tumor lysis.

Colorectal cancer (CRC) cells harboring KRAS or BRAF mutations show a more-malignant phenotype than cells with wild-type KRAS and BRAF. KRAS/BRAF-wild-type CRCs are sensitive to epidermal growth factor receptor (EGFR)-targeting agents, whereas KRAS/BRAF-mutant CRCs are resistant due to constitutive activation of the EGFR-downstream KRAS/BRAF signaling pathway. Novel therapeutic strategies to treat KRAS/BRAF mutant CRC cells are thus needed. We recently demonstrated that the telomerase-specific replication-competent oncolytic adenoviruses OBP-301 and p53-armed OBP-702 exhibit therapeutic potential against KRAS-mutant human pancreatic cancer cells. In this study, we evaluated the therapeutic potential of OBP-301 and OBP-702 against human CRC cells with differing KRAS/BRAF status. Human CRC cells with wild-type KRAS/BRAF (SW48, Colo320DM, CACO-2), mutant KRAS (DLD-1, SW620, HCT116), and mutant BRAF (RKO, HT29, COLO205) were used in this study. The antitumor effect of OBP-301 and OBP-702 against CRC cells was analyzed using the XTT assay. Virus-mediated modulation of apoptosis, autophagy, and the EGFR-MEK-ERK and AKT-mTOR signaling pathways was analyzed by Western blotting. Wild-type and KRAS-mutant CRC cells were sensitive to OBP-301 and OBP-702, whereas BRAF-mutant CRC cells were sensitive to OBP-702 but resistant to OBP-301. Western blot analysis demonstrated that OBP-301 induced autophagy and that OBP-702 induced autophagy and apoptosis in human CRC cells. In BRAF-mutant CRC cells, OBP-301 and OBP-702 suppressed the expression of EGFR, MEK, ERK, and AKT proteins, whereas mTOR expression was suppressed only by OBP-702. Our results suggest that p53-armed oncolytic virotherapy is a viable therapeutic option for treating KRAS/BRAF-mutant CRC cells via induction of autophagy and apoptosis.

Abstract Background Gastric yolk sac tumor (YST)-like carcinoma is extremely rare, and its prognosis is poor, because most patients have widespread metastases at the time of diagnosis. We report a case of gastric YST-like carcinoma with an adenocarcinoma component without metastases in which curative resection was performed. Case presentation A 77-year-old man complaining of melena and dizziness due to anemia was diagnosed with poorly differentiated adenocarcinoma in the gastric cardia, with a benign ulcer in the gastric body. He underwent total gastrectomy with D2 lymph node dissection for the tumor. Histological examination of the resected specimens revealed a mixture of reticular and glandular neoplastic components morphologically. In the reticular area, an endodermal sinus pattern and some Schiller–Duval bodies were confirmed. Gastric YST-like carcinoma with adenocarcinoma components, T2N0M0 Stage IB, was diagnosed. Immunohistochemical analysis showed that the YST was positive for carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP) and p53. In contrast, the adenocarcinoma was positive for p53 and negative for CEA and AFP. The patient remained healthy as of 7 years postoperatively, with no recurrence. Conclusions Routine medical examinations or endoscopic examinations for accidental symptom may be helpful for early diagnosis and good prognosis for gastric YST-like carcinoma, although the prognosis is generally poor.

Abstract Background Peritoneal dissemination often develops in gastric cancer. Tumor-associated macrophages (TAMs) are present in the peritoneal cavity of gastric cancer patients with peritoneal dissemination, facilitating tumor progression. However, the mechanism by which macrophages differentiate into tumor-associated macrophages in the peritoneal cavity is not well understood. In this study, the interplay between gastric cancer-derived extracellular vesicles (EVs) and macrophages was investigated. Methods The association between macrophages and EVs in peritoneal ascitic fluid of gastric cancer patients, or from gastric cancer cell lines was examined, and their roles in differentiation of macrophages and potentiation of the malignancy of gastric cancer were further explored. Results Immunofluorescent assays of the ascitic fluid showed that M2 macrophages were predominant along with the cancer cells in the peritoneal cavity. EVs purified from gastric cancer cells, as well as malignant ascitic fluid, differentiated peripheral blood mononuclear cell-derived macrophages into the M2-like phenotype, which was demonstrated by their morphology and expression of CD163/206. The macrophages differentiated by gastric cancer-derived EVs promoted the migration ability of gastric cancer cells, and the EVs carried STAT3 protein. Conclusion EVs derived from gastric cancer play a role by affecting macrophage phenotypes, suggesting that this may be a part of the underlying mechanism that forms the intraperitoneal cancer microenvironment.

Abstract Cancer-associated fibroblasts (CAFs) have an important role in the tumor microenvironment. CAFs have the multifunctionality which strongly support cancer progression and the acquisition of therapeutic resistance by cancer cells. Near-infrared photoimmunotherapy (NIR-PIT) is a novel cancer treatment that uses a highly selective monoclonal antibody (mAb)-photosensitizer conjugate. We developed fibroblast activation protein (FAP)-targeted NIR-PIT, in which IR700 was conjugated to a FAP-specific antibody to target CAFs (CAFs-targeted NIR-PIT: CAFs-PIT). Thus, we hypothesized that the control of CAFs could overcome the resistance to conventional chemotherapy in esophageal cancer (EC). In this study, we evaluated whether EC cell acquisition of stronger malignant characteristics and refractoriness to chemoradiotherapy are mediated by CAFs. Next, we assessed whether the resistance could be rescued by eliminating CAF stimulation by CAFs-PIT in vitro and in vivo. Cancer cells acquired chemoradiotherapy resistance via CAF stimulation in vitro and 5-fluorouracil (FU) resistance in CAF-coinoculated tumor models in vivo. CAF stimulation promoted the migration/invasion of cancer cells and a stem-like phenotype in vitro, which were rescued by elimination of CAF stimulation. CAFs-PIT had a highly selective effect on CAFs in vitro. Finally, CAF elimination by CAFs-PIT in vivo demonstrated that the combination of 5-FU and NIR-PIT succeeded in producing 70.9% tumor reduction, while 5-FU alone achieved only 13.3% reduction, suggesting the recovery of 5-FU sensitivity in CAF-rich tumors. In conclusion, CAFs-PIT could overcome therapeutic resistance via CAF elimination. The combined use of novel targeted CAFs-PIT with conventional anticancer treatments can be expected to provide a more effective and sensible treatment strategy.

Neuroblastoma (NB) is a primary malignant tumor of the peripheral sympathetic nervous system. High-risk NB is characterized by MYCN amplification and human telomerase reverse transcriptase (hTERT) rearrangement, contributing to hTERT activation and a poor outcome. For targeting hTERT-activated tumors, we developed two oncolytic adenoviruses, OBP-301 and tumor suppressor p53-armed OBP-702, in which the hTERT promoter drives expression of the viral E1 gene for tumor-specific virus replication. In this study, we demonstrate the therapeutic potential of the hTERT-driven oncolytic adenoviruses OBP-301 and OBP-702 using four human MYCN-amplified NB cell lines (IMR-32, CHP-134, NB-1, LA-N-5) exhibiting high hTERT expression. OBP-301 and OBP-702 exhibited a strong antitumor effect in association with autophagy in NB cells. Virus-mediated activation of E2F1 protein suppressed MYCN expression. OBP-301 and OBP-702 significantly suppressed the growth of subcutaneous CHP-134 tumors. Thus, these hTERT-driven oncolytic adenoviruses are promising antitumor agents for eliminating MYCN-amplified NB cells via E2F1-mediated suppression of MYCN protein.

Peritoneal metastasis is the most frequent form of distant metastasis and recurrence in gastric cancer, and the prognosis is extremely poor due to the resistance of systemic chemotherapy. Here, we demonstrate that intraperitoneal (i.p.) administration of a green fluorescence protein (GFP)-expressing attenuated adenovirus with oncolytic potency (OBP-401) synergistically suppressed the peritoneal metastasis of gastric cancer in combination with paclitaxel (PTX). OBP-401 synergistically suppressed the viability of human gastric cancer cells in combination with PTX. PTX enhanced the antitumor effect of OBP-401 due to enhanced viral replication in cancer cells. The combination therapy increased induction of mitotic catastrophe, resulting in accelerated autophagy and apoptosis. Peritoneally disseminated nodules were selectively visualized as GFP-positive spots by i.p. administration of OBP-401 in an orthotopic human gastric cancer peritoneal dissemination model. PTX enhanced the deep penetration of OBP-401 into the disseminated nodules. Moreover, a non-invasive in vivo imaging system demonstrated that the combination therapy of i.p. OBP-401 administration with PTX significantly inhibited growth of peritoneal metastatic tumors and the amount of malignant ascites. i.p. virotherapy with PTX may be a promising treatment strategy for the peritoneal metastasis of gastric cancer.

Abstract Immune checkpoint inhibitor‐induced diabetes mellitus is a rare immune‐related adverse event. This report illustrates clinical data and insulin secretory ability before and after the onset of immune checkpoint inhibitor‐induced diabetes.

Endoscopic ultrasound (EUS)-guided transgastric drainage has been performed as a less invasive procedure for pancreatic fistulas and intra-abdominal abscesses occurring after surgery in recent years. However, there are no reports of EUS-guided transgastric drainage of intra-abdominal abscesses following gastrectomy. This case report describes 2 patients who developed an intra-abdominal abscess following gastrectomy and underwent EUS-guided transgastric drainage. Both patients underwent laparoscopy-assisted distal gastrectomy with Billroth-I reconstruction for gastric cancer. The intra-abdominal abscesses were caused by postoperative pancreatic fistula that developed following gastrectomy. One patient underwent naso-cystic drainage and the other underwent only a needle puncture of the abscess cavity. EUS-guided drainage was performed safely and effectively, although 1 patient developed gastroduodenal anastomotic leakage related to this procedure. In summary, EUS-guided transgastric drainage is safe and technically feasible even in post-gastrectomy patients. However, it is necessary to be careful if this procedure is performed in the early period following gastrectomy.

Abstract Background The peritoneum is one of the most frequent metastatic sites in pancreatic cancer patients, and peritoneal dissemination makes this disease refractory due to aggressive progression and chemoresistance. Although the role of the tumor microenvironment in cancer development is recognized, the correlation between the peritoneal environment and refractoriness of peritoneal dissemination remains unclear. The intraperitoneal tumor-microenvironment and its potential role in the progression of peritoneal dissemination and chemo-refractoriness, focusing especially on macrophages, were investigated. Materials and methods Peritoneal washes were obtained from pancreatic cancer patients, and cellular components were subjected to immunofluorescence assays. The effects of macrophages induced from monocytic THP-1 cells on pancreatic cancer cells were examined in co-culture conditions. The in vivo effects of macrophages on tumor growth and chemo-sensitivity were investigated by subcutaneously or intraperitoneally co-injecting cancer cells with macrophages into mice. Results CD204-positive macrophages were present along with cancer cells in the peritoneal washes. In in vitro co-culture, tumor-associated macrophages affected pancreatic cancer cells, induced the epithelial-to-mesenchymal transition (EMT), and made them more resistant to chemotherapeutic agents. M2 macrophages promoted growth of both subcutaneous tumors and peritoneal dissemination in mice. Furthermore, co-inoculation of M2 macrophages conferred chemoresistance in the peritoneal dissemination mouse model, which significantly shortened their survival. Conclusion Intraperitoneal tumor-associated macrophages potentially play an important role in promotion of peritoneal dissemination and chemoresistance of pancreatic cancer via EMT induction.

Soft tissue sarcoma (STS) is a rare cancer that develops from soft tissues in any part of the body. Despite major advances in the treatment of STS, patients are often refractory to conventional radiotherapy, leading to poor prognosis. Enhancement of sensitivity to radiotherapy would therefore improve the clinical outcome of STS patients. We previously revealed that the tumor-specific, replication-competent oncolytic adenovirus OBP-301 kills human sarcoma cells. In this study, we investigated the radiosensitizing effect of OBP-301 in human STS cells. The in vitro antitumor effect of OBP-301 and ionizing radiation in monotherapy or combination therapy was assessed using highly radiosensitive (RD-ES and SK-ES-1) and moderately radiosensitive (HT1080 and NMS-2) STS cell lines. The expression of markers for apoptosis and DNA damage were evaluated in STS cells after treatment. The therapeutic potential of combination therapy was further analyzed using SK-ES-1 and HT1080 cells in subcutaneous xenograft tumor models. The combination of OBP-301 and ionizing radiation showed a synergistic antitumor effect in all human STS cell lines tested, including those that show different radiosensitivity. OBP-301 was found to enhance irradiation-induced apoptosis and DNA damage via suppression of anti-apoptotic myeloid cell leukemia 1 (MCL1), which was expressed at higher levels in moderately radiosensitive cell lines. The combination of OBP-301 and ionizing radiation showed a more profound antitumor effect compared to monotherapy in SK-ES-1 (highly radiosensitive) and HT1080 (moderately radiosensitive) subcutaneous xenograft tumors. OBP-301 is a promising antitumor reagent to improve the therapeutic potential of radiotherapy by increasing radiation-induced apoptosis in STS.

BackgroundAlthough proximal gastrectomy (PG) is a recognized surgical procedure for early proximal gastric cancer, total gastrectomy (TG) is sometimes selected due to concern about severe gastroesophageal reflux. Esophagogastrostomy by the double-flap technique (DFT) is an anti-reflux reconstruction after PG, and its short-term effectiveness has been reported. However, little is known about the long-term effects on nutritional status and quality of life (QOL).MethodsGastric cancer patients who underwent laparoscopy-assisted PG (LAPG) with DFT or laparoscopy-assisted TG (LATG) between April 2011 and March 2014 were retrospectively analyzed. Body weight (BW), body mass index (BMI), and prognostic nutritional index (PNI) were reviewed to assess nutritional status, and the Postgastrectomy Syndrome Assessment Scale (PGSAS)-45 was used to assess QOL.ResultsA total of 36 patients (LATG: 17, LAPG: 19) were enrolled. Four of 17 LATG patients (24%) were diagnosed with Stage ≥II after surgery, and half received S-1 adjuvant chemotherapy. BW and PNI were better maintained in LAPG than in LATG patients until 1-year follow-up. Seven of 16 LATG patients (44%) were categorized as "underweight (BMIConclusionsLAPG with DFT was superior to LATG in postoperative nutritional maintenance, and can be the first option for early proximal gastric cancer.

A solid tumor consists of cancer and stromal cells, which comprise the tumor microenvironment (TME). Tumor-associated macrophages (TAMs) are usually abundant in the TME, contributing to tumor progression. In cases of peritoneal dissemination of gastric cancer (GC), the contribution of intraperitoneal TAMs remains unclear. Macrophages from peritoneal washings of GC patients were analyzed, and the link between intraperitoneal TAMs and GC cells was investigated to clarify the interaction between them in peritoneal dissemination. Macrophages were predominant among leukocytes constituting the microenvironment of the peritoneal cavity. The proportion of CD163-positive TAMs was significantly higher in stage IV than in stage I GC. Co-culture with TAMs potentiated migration and invasion of GC. IL-6 was the most increased in the medium of in vitro co-culture of macrophages and GC, and IL-6 elevation was also observed in the peritoneal washes with peritoneal dissemination. An elevated concentration of intraperitoneal IL-6 was correlated with a poor prognosis in clinical cases. In conclusion, intraperitoneal TAMs are involved in promoting peritoneal dissemination of GC via secreted IL-6. TAM-derived IL-6 could be a potential therapeutic target for peritoneal dissemination of GC.

Abstract Oncolytic virotherapy has the disadvantage of being unsuitable for systemic delivery due to immune elimination. Liposomal encapsulation is well-recognized to reduce immune elimination and enhance the stability of drugs in the bloodstream. In the present study, the potential of liposome-encapsulated plasmid DNA of telomerase-specific oncolytic adenovirus (TelomeScan) expressing GFP (Lipo-pTS) as an oncolytic adenoviral agent suitable for systemic delivery was investigated. Lipo-pTS, which has a diameter of 40–50 nm, showed potent antitumor effects on HCT116 colon carcinoma cells in vitro and in vivo. Tumor selectivity of Lipo-pTS was independent of coxsackie and adenovirus receptor (CAR). Importantly, Lipo-pTS reduced production of adenovirus-neutralizing antibodies (AdNAbs) after intravenous administration into immune-competent mice compared to TelomeScan, and even in the presence of AdNAbs, Lipo-pTS maintained strong cytotoxicity. In conclusion, Lipo-pTS has the potential to become an oncolytic adenoviral agent suitable for systemic delivery with the characteristics of CAR-independent antitumor activity and a stealth effect on the immune system.

Abstract Background Endoscopic resection (ER) has been widely accepted as the standard treatment for early gastric cancer (EGC). However, in patients considered to have undergone non-curative ER due to their potential risk of lymph node metastasis (LNM), additional gastrectomy is recommended. The aim of the present study was to identify EGC patients after non-curative ER at high risk of LNM. Methods A total of 150 patients who had undergone ER for EGC were diagnosed as non-curative ER due to their potential risk of LNM. Clinicopathological data and clinical outcomes were examined retrospectively. Results Additional gastrectomy with lymph node dissection was performed in 73 patients, and the remaining 77 patients were followed-up without additional gastrectomy. In patients who underwent additional gastrectomy, 8 patients had local residual tumor, and 8 patients had LNM, which were limited in the peritumoral nodes. Only lymphatic invasion (p = 0.012) was a statistically significant factor for LNM. The 5-year overall survival and recurrence-free survival were not significantly different between patients with and without additional gastrectomy. Conclusion Additional gastrectomy with lymph node dissection is recommended for patients who were diagnosed as non-curative ER with lymphatic invasion, and minimizing the extent of lymph node dissection may be allowed for these patients.

Oncolytic virotherapy is one of the most promising, emerging cancer therapeutics. We generated three types of telomerase-specific replication-competent oncolytic adenovirus: OBP-301; a green fluorescent protein (GFP)-expressing adenovirus, OBP-401; and Killer-Red-armed OBP-301. These oncolytic adenoviruses are driven by the human telomerase reverse transcriptase (hTERT) promoter; therefore, they conditionally replicate preferentially in cancer cells. Fluorescence imaging enables visualization of invasion and metastasis in vivo at the subcellular level; including molecular dynamics of cancer cells, resulting in greater precision therapy. In the present review, we focused on fluorescence imaging applications to develop precision targeting for oncolytic virotherapy. Cell-cycle imaging with the fluorescence ubiquitination cell cycle indicator (FUCCI) demonstrated that combination therapy of an oncolytic adenovirus and a cytotoxic agent could precisely target quiescent, chemoresistant cancer stem cells (CSCs) based on decoying the cancer cells to cycle to S-phase by viral treatment, thereby rendering them chemosensitive. Non-invasive fluorescence imaging demonstrated that complete tumor resection with a precise margin, preservation of function, and prevention of distant metastasis, was achieved with fluorescence-guided surgery (FGS) with a GFP-reporter adenovirus. A combination of fluorescence imaging and laser ablation using a KillerRed-protein reporter adenovirus resulted in effective photodynamic cancer therapy (PDT). Thus, imaging technology and the designer oncolytic adenoviruses may have clinical potential for precise cancer targeting by indicating the optimal time for administering therapeutic agents; accurate surgical guidance for complete resection of tumors; and precise targeted cancer-specific photosensitization.

Fluorescence-guided surgery (FGS) of cancer is an area of intense development. In the present report, we demonstrate that the telomerase-dependent green fluorescent protein (GFP)-containing adenovirus OBP-401 could label colon-cancer liver metastasis in situ in an orthotopic mouse model enabling successful FGS. OBP-401-GFP-labeled liver metastasis resulted in complete resection with FGS, in contrast, conventional bright-light surgery (BLS) did not result in complete resection of the metastasis. OBP-401-FGS reduced the recurrence rate and prolonged over-all survival compared with BLS. In conclusion, adenovirus OBP-401 is a powerful tool to label liver metastasis in situ with GFP which enables its complete resection, not possible with conventional BLS.

Stomach cancer carcinomatosis peritonitis (SCCP) is a recalcitrant disease. The goal of the present study was to establish an in vitro-in vivo-like imageable model of SCCP to develop cell-cycle-based therapeutics of SCCP. We established 3-D Gelfoam® histoculture and tumor-sphere models of SCCP. FUCCI-expressing MKN-45 stomach cancer cells were transferred to express the fluorescence ubiquinized cell-cycle indicator (FUCCI). FUCCI-expressing MKN-45 cells formed spheres on agarose or on Gelfoam® grew into tumor-like structures with G0/G1 cancer cells in the center and S/G2 cancer cells located in the surface as indicated by FUCCI imaging when the cells fluoresced red or green, respectively. We treated FUCCI-expressing cancer cells forming SCCP tumors in Gelfoam® histoculture with OBP-301, cisplatinum (CDDP), or paclitaxel. CDDP or paclitaxel killed only cycling cancer cells and were ineffective against G1/G2 MKN-45 cells in tumors growing on Gelfoam®. In contrast, the telomerase-dependent adenovirus OBP-301 decoyed the MKN-45 cells in tumors on Gelfoam® to cycle from G0/G1 phase to S/G2 phase and reduced their viability. CDDP- or paclitaxel-treated MKN-45 tumors remained quiescent and did not change in size. In contrast, OB-301 reduced the size of the MKN-45 tumors on Gelfoam®. We examined the cell cycle-related proteins using Western blotting. CDDP increased the expression of p53 and p21 indicating cell cycle arrest. In contrast, OBP-301 decreased the expression of p53 and p21 Furthermore, OBP-301 increased the expression of E2F and pAkt as further indication of cell cycle decoy. This 3-D Gelfoam® histoculture and FUCCI imaging are powerful tools to discover effective therapy of SCCP such as OBP-301.

Although splenectomy is often performed along with en bloc node dissection in gastric cancer surgery, portal/splenic vein thrombosis (PSVT) has been rarely reported. We recently encountered a case of PSVT after a splenectomy was performed during gastric cancer surgery. A 53-year-old woman underwent total gastrectomy, splenectomy, and en bloc regional lymph node dissection for gastric cancer. An uneventful postoperative course ended with abrupt development of a fever and general fatigue. Laboratory tests showed elevated levels of liver transaminases and fibrinogen degenerative products. Contrast-enhanced computed tomography revealed splenic vein thrombosis and partial liver infarction. Immediate anticoagulant treatment resulted in clinical improvement and partial thrombolysis in 2 months. PSVT after splenectomy in haematological disorders has been recognized as a possibly lethal complication. However, it has been underappreciated in cases of splenectomy for gastric cancer. The present case demonstrates the importance of considering PSVT as a possible complication of splenectomy in gastric cancer surgery.

To improve the outcome of patients suffering from gastric cancer, a better understanding of underlying genetic and epigenetic events in this malignancy is required. Although CpG island methylator phenotype (CIMP) and microsatellite instability (MSI) have been shown to play pivotal roles in gastric cancer pathogenesis, the clinical significance of these events on survival outcomes in patients with gastric cancer remains unknown.This study included a patient cohort with pathologically confirmed gastric cancer who had surgical resections. A cohort of 68 gastric cancers was analyzed. CIMP and MSI statuses were determined by analyzing promoter CpG island methylation status of 28 genes/loci, and genomic instability at 10 microsatellite markers, respectively. A Cox's proportional hazards model was performed for multivariate analysis including age, stage, tumor differentiation, KRAS mutation status, and combined CIMP/MLH1 methylation status in relation to overall survival (OS).By multivariate analysis, longer OS was significantly correlated with lower pathologic stage (P = 0.0088), better tumor differentiation (P = 0.0267) and CIMP-high and MLH1 3' methylated status (P = 0.0312). Stratification of CIMP status with regards to MLH1 methylation status further enabled prediction of gastric cancer prognosis.CIMP and/or MLH1 methylation status may have a potential to be prognostic biomarkers for patients with gastric cancer.

Oncolytic virotherapy has recently emerged as a promising strategy for inducing tumor-specific cell death. Adenoviruses are widely and frequently used in oncolytic virotherapy. The mechanism of oncolytic adenovirus-mediated tumor suppression involves virus-induced activation of the autophagic machinery in tumor cells. Autophagy is a cytoprotective process that produces energy via lysosomal degradation of intracellular components as a physiologic response to various stresses, including hypoxia, nutrient deprivation, and disruption of growth signaling. However, infection with oncolytic adenoviruses induces autophagy and subsequent death of tumor cells rather than enhancing their survival. In this review, we summarize the beneficial role of autophagy in oncolytic adenoviral therapy, including the roles of infection, replication, and cell lysis. Numerous factors are involved in the promotion and inhibition of oncolytic adenovirus-mediated autophagy. Furthermore, recent evidence has shown that oncolytic adenoviruses induce autophagy-related immunogenic cell death (ICD), which enhances the antitumor immune response by inducing the activation of danger signal molecules and thus represents a novel cancer immunotherapy. Understanding the precise role of oncolytic adenovirus-induced autophagy and ICD could enhance the therapeutic potential of oncolytic adenoviral therapy for treating various cancers.

Orthotopic models of various types of tumors are widely used in anti-tumor therapeutic experiments in preclinical studies. However, there are few ways to appropriately monitor therapeutic effect in orthotopic tumor models, especially for tumors invisible from the outside. In this study we aimed to establish a non-invasive semi-quantitative bioluminescent imaging method of monitoring an orthotopic esophageal cancer mouse model. We confirmed that the TE8 esophageal cancer cell line implanted orthotopically into the abdominal esophagus of nu/nu mice (n = 5) developed not only a main tumor at the implanted site, but also local lymph node metastases and peritoneal disseminations within 6 weeks after inoculation. We established a TE8 cell line that stably expressed the firefly luciferase gene (TE8-Luc). We showed that TE8-Luc cells implanted subcutaneously into nu/nu mice (n = 5) grew over time until 5 weeks after inoculation. Tumor volume was strongly correlated with luminescent intensity emitted from the tumor, which was quantified using the IVIS imaging system. We then showed that TE8-Luc cells implanted orthotopically into the mouse abdominal esophagus (n = 8) also formed a tumor and that the luminescent intensity of such a tumor, as detected by IVIS, increased over time until 7 weeks after inoculation and was therefore likely to reflect tumor progression. We therefore propose that this orthotopic esophageal cancer model, monitored using the non-invasive semi-quantitative IVIS imaging system, will be useful for in vivo therapeutic experiments against esophageal cancer. This experimental setting is expected to contribute to the development of novel therapeutic technologies for esophageal cancer in preclinical studies.

Hypoxia is a microenvironmental factor that contributes to the invasion, progression and metastasis of tumor cells. Hypoxic tumor cells often show more resistance to conventional chemoradiotherapy than normoxic tumor cells, suggesting the requirement of novel antitumor therapies to efficiently eliminate the hypoxic tumor cells. We previously generated a tumor-specific replication-competent oncolytic adenovirus (OBP-301: Telomelysin), in which the human telomerase reverse transcriptase (hTERT) promoter drives viral E1 expression. Since the promoter activity of the hTERT gene has been shown to be upregulated by hypoxia, we hypothesized that, under hypoxic conditions, the antitumor effect of OBP-301 with the hTERT promoter would be more efficient than that of the wild-type adenovirus 5 (Ad5). In this study, we investigated the antitumor effects of OBP-301 and Ad5 against human cancer cells under a normoxic (20% oxygen) or a hypoxic (1% oxygen) condition. Hypoxic condition induced nuclear accumulation of the hypoxia-inducible factor-1α and upregulation of hTERT promoter activity in human cancer cells. The cytopathic activity of OBP-301 was significantly higher than that of Ad5 under hypoxic condition. Consistent with their cytopathic activity, the replication of OBP-301 was significantly higher than that of Ad5 under the hypoxic condition. OBP-301-mediated E1A was expressed within hypoxic areas of human xenograft tumors in mice. These results suggest that the cytopathic activity of OBP-301 against hypoxic tumor cells is mediated through hypoxia-mediated activation of the hTERT promoter. Regulation of oncolytic adenoviruses by the hTERT promoter is a promising antitumor strategy, not only for induction of tumor-specific oncolysis, but also for efficient elimination of hypoxic tumor cells.