Satoru Kikuchi

Nonexposure laparoscopic and endoscopic cooperative surgery (closed laparoscopic and endoscopic cooperative surgery) for gastric submucosal tumor.

Laparoscopic and endoscopic cooperative surgery (LECS) is increasingly applied for gastric submucosal tumors (SMTs) such as gastrointestinal stromal tumors. However, the conventional LECS procedure has the potential risk that gastric contents and even tumor cells could spread into the abdominal cavity because the gastric wall has to be opened during the resection. To avoid this problem, we have developed a modified LECS procedure named “closed LECS.” Ten patients underwent closed LECS for the resection of gastric SMTs. Closed LECS consists of the following steps: endoscopic submucosal layer dissection around the tumor, laparoscopic marking of a resection line on the serosal surface along submucosal dissection line, seromuscular suturing with the marked lesion inverted into the inside of the stomach, endoscopic circumferential seromuscular dissection, and peroral retrieval. In three of the initial five cases, the closed LECS procedure was not completed as planned because of the tumor size and endoscopic inappropriate seromuscular dissection. After modification of the procedure, the entire procedure was successful in all five cases. The mean resected tumor diameter was 24.1xa0±xa07.6xa0mm. The mean operation time was 253xa0±xa045xa0min. One patient experienced an intra-abdominal abscess potentially related to delayed perforation as a postoperative complication. The closed LECS procedure for gastric SMTs can theoretically be applied without contamination and tumor cell dissemination into the abdominal cavity.

Establishment of a Non-Invasive Semi-Quantitative Bioluminescent Imaging Method for Monitoring of an Orthotopic Esophageal Cancer Mouse Model.

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 (nu200a=u200a5) 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 (nu200a=u200a5) 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 (nu200a=u200a8) 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.

Targeted Photodynamic Virotherapy Armed with a Genetically Encoded Photosensitizer

Photodynamic therapy (PDT) is a minimally invasive antitumor therapy that eradicates tumor cells through a photosensitizer-mediated cytotoxic effect upon light irradiation. However, systemic administration of photosensitizer often makes it difficult to avoid a photosensitive adverse effect. The red fluorescent protein KillerRed generates reactive oxygen species (ROS) upon green light irradiation. Here, we show the therapeutic potential of a novel tumor-specific replicating photodynamic viral agent (TelomeKiller) constructed using the human telomerase reverse transcriptase (hTERT) promoter. We investigated the light-induced antitumor effect of TelomeKiller in several types of human cancer cell lines. Relative cell viability was investigated using an XTT assay. The in vivo antitumor effect was assessed using subcutaneous xenografted tumor and lymph node metastasis models. KillerRed accumulation resulted in ROS generation and apoptosis in light-irradiated cancer cells. Intratumoral injection of TelomeKiller efficiently delivered the KillerRed protein throughout the tumors and exhibited a long-lasting antitumor effect with repeated administration and light irradiation in mice. Moreover, intratumorally injected TelomeKiller could spread into the regional lymph node area and eliminate micrometastasis with limited-field laser irradiation. Our results suggest that KillerRed has great potential as a novel photosensitizer if delivered with a tumor-specific virus-mediated delivery system. TelomeKiller-based PDT is a promising antitumor strategy to efficiently eradicate tumor cells. Mol Cancer Ther; 15(1); 199–208. ©2015 AACR.

Biological Ablation of Sentinel Lymph Node Metastasis in Submucosally Invaded Early Gastrointestinal Cancer

Currently, early gastrointestinal cancers are treated endoscopically, as long as there are no lymph node metastases. However, once a gastrointestinal cancer invades the submucosal layer, the lymph node metastatic rate rises to higher than 10%. Therefore, surgery is still the gold standard to remove regional lymph nodes containing possible metastases. Here, to avoid prophylactic surgery, we propose a less-invasive biological ablation of lymph node metastasis in submucosally invaded gastrointestinal cancer patients. We have established an orthotopic early rectal cancer xenograft model with spontaneous lymph node metastasis by implantation of green fluorescent protein (GFP)-labeled human colon cancer cells into the submucosal layer of the murine rectum. A solution containing telomerase-specific oncolytic adenovirus was injected into the peritumoral submucosal space, followed by excision of the primary rectal tumors mimicking the endoscopic submucosal dissection (ESD) technique. Seven days after treatment, GFP signals had completely disappeared indicating that sentinel lymph node metastasis was selectively eradicated. Moreover, biologically treated mice were confirmed to be relapse-free even 4 weeks after treatment. These results indicate that virus-mediated biological ablation selectively targets lymph node metastasis and provides a potential alternative to surgery for submucosal invasive gastrointestinal cancer patients.

Sarcopenia and Comorbidity in Gastric Cancer Surgery as a Useful Combined Factor to Predict Eventual Death from Other Causes

BackgroundSarcopenia is recognized as an important prognostic factor in various types of cancer, including gastric cancer. While long-term survival analyses typically focus on overall and disease-specific survival, death from other causes has received far less attention.MethodsWe reviewed medical records of 491 gastric cancer patients who underwent gastrectomy from January 2005 to March 2014 and whose preoperative computed tomography (CT) images were available for evaluation of sarcopenia. Sarcopenia was defined as the SMA/BSA index (skeletal muscle area divided by body surface area) below the sex-specific lowest quartile.ResultsSarcopenia was significantly associated with age, high body mass index (BMI), presence of comorbidity, high American Society of Anesthesiologists physical status (ASA-PS), high T score, advanced stage, large blood loss, and long hospital stay, but was not significantly associated with postoperative complications. Univariate and multivariate analyses of prognostic factors for overall survival revealed that sarcopenia is an independent predictor of poor prognosis [hazard ratio (HR) 1.46, 95% confidence interval (CI) 1.01–2.09, pxa0u2009=u2009xa00.0454]. Our analysis of death due to other causes found that non-gastric cancer-related deaths were more frequent among sarcopenia patients with comorbidities than in the rest of our study population (pxa0u2009=u2009xa00.0001), while univariate and multivariate analyses revealed that sarcopenia with comorbidity was an independent risk factor for non-gastric cancer-related death (HR 1.84, 95% CI 1.31–3.61, pxa0u2009=u2009xa00.0308), as was age.ConclusionFor gastric cancer patients, sarcopenia increases the risk of death from other causes following surgery, which reveals the importance of developing treatment strategies based not only on cancer status but also on other clinical factors, including sarcopenia and comorbidity.

Management of early gastric cancer that meet the indication for radical lymph node dissection following endoscopic resection: a retrospective cohort analysis

BackgroundEndoscopic 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.MethodsA 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.ResultsAdditional 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 (pxa0=xa00.012) 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.ConclusionAdditional 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.

Abstract 5011: Tumor associated macrophages promote malignant phenotypes of disseminated human gastric cancer cells in intraperitoneal cancer immune microenvironment

Gastric cancer is the third leading cause of cancer-related death, and peritoneal dissemination is one of the most frequent site of recurrence. Although the role of tumor microenvironment is recognized, it is still unclear how intraperitoneal cancer-immune microenvironment contributes to peritoneal metastasis. Thus, we investigated the interaction between intraperitoneal cancer and immune cells, especially focusing on tumor-associated macrophages (TAM) in the peritoneal cavity. The peritoneal wash from gastric cancer patients was subjected to conventional cytology, flow cytometry, and immuno-fluorescent assay using antibodies against CD45 (leukocytes), CD14 (monocytes), CD80/163 (M1/M2 macrophages, respectively), in combination with genetically engineered cancer-imaging viral agent ‘TelomeScan’ which specifically expresses GFP in telomerase-positive cells. In cytology-positive samples, CD163-positive macrophages could be detected in approximately 70% of intraperitoneal macrophages with TelomeScan-positive cancer cells, while cytology negative samples contained few CD163-positive macrophages. In addition, peripheral blood mononuclear cells (PBMCs) from healthy volunteers were induced to differentiate into CD163-positive M2 macrophages (TAM-like macrophages), and co-cultured with gastric cancer cells to examine the effect on their malignant phenotype such as migration and invasion. We found that PBMCs-derived CD163-positive M2 macrophages significantly potentiated the ability of migration and invasion in gastric cancer cells. In case of existence of free cancer cells in peritoneal cavity, intraperitoneal macrophages appeared to differentiate into TAM and they potentially accelerate malignant phenotypes of gastric cancer cells. These results suggested that intraperitoneal cancer-immune microenvironment may play an important role to promote peritoneal disseminations in gastric cancer. Citation Format: Shuichi Sakamoto, Shunsuke Kagawa, Kazuya Kuwada, Atene Ito, Tetsuya Kagawa, Satoru Kikuchi, Shinji Kuroda, Ryuichi Yoshida, Hiroshi Tazawa, Toshiyoshi Fujiwara. Tumor associated macrophages promote malignant phenotypes of disseminated human gastric cancer cells in intraperitoneal cancer immune microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5011. doi:10.1158/1538-7445.AM2017-5011

A case of right-sided Bochdalek hernia incidentally diagnosed in a gastric cancer patient

BackgroundBochdalek hernia (BH) is generally congenital, presenting with respiratory distress. However, this pathology is rarely detected in adults. Some adult cases of BH present with symptoms attributed to the hernia, but incidental detection of BH is increasing among asymptomatic adults due to advances in imaging modalities. This report presents the management of incidental BH patients detected in the preoperative period of gastric cancer.Case presentationAn asymptomatic 76-year-old woman was diagnosed with advanced gastric cancer during follow-up after radiotherapy for uterine cervical cancer. Computed tomography (CT) was performed to exclude metastatic gastric cancer, incidentally detecting right-sided BH. We planned distal gastrectomy with lymph node dissection for gastric cancer and simultaneous repair of BH using a laparoscopic approach. We performed laparoscopic gastrectomy for gastric cancer and investigated the right-sided BH to assess whether repair during surgery was warranted. Herniation of the liver into the right hemithorax was observed, but was followed-up without surgical repair because the right hepatic lobe was adherent to the remnant right anterior hemidiaphragm and covered the huge defect in the right hemidiaphragm. No intra- or postoperative pneumothorax was observed during pneumoperitoneum.ConclusionRegardless of symptoms, repair of adult BH is generally recommended to prevent visceral incarceration. However, BH in asymptomatic adults appears to be more common than previously reported in the literature. Surgeons need to consider the management of incidental BH encountered during thoracic or abdominal surgery.

Identifying the needs for teaching fundamental knowledge of laparoscopic surgery: a cross-sectional study in Japan

BackgroundRecently, laparoscopic surgery (LS) has become a more common procedure than traditional open surgery. Although LS-related adverse events have been reported, there is no formal, standardized curriculum to teach the fundamentals of LS in Japan. Understanding surgeons’ knowledge regarding LS is crucial for developing an educational curriculum. The purpose of this study was to determine the baseline knowledge on LS of surgeons and surgical trainees in Japan.MethodsParticipants completed 24 multiple-choice questions testing basic cognitive knowledge of LS and a questionnaire regarding the status of laparoscopic education. The examination was developed according to the 13 content domains of the Fundamentals of Laparoscopic Surgery (FLS) program. Scores were compared between post-graduate year (PGY)u2009>u20095 and PGY 1–5 participants. Data are expressed as median scores and interquartile ranges. Wilcoxon signed-rank test was used for statistical analysis.ResultsA total of 195 surgeons and surgical trainees from 10 teaching hospitals (PGY1–5: 66, PGYu2009>u20095: 129) across Japan completed the examination. The median score in the entire cohort was 75 [67; 83] %, with significantly higher scores in the PGYu2009>u20095 group compared to the PGY1–5 group (79 [75; 83] % vs. 67 [58; 75] %, pu2009<u20090.001). The differences in performance were due to better scores for PGYu2009>u20095 group on the sections “equipment,” “patient considerations,” “abdominal access,” “tissue handling,” “hemorrhage and hemostasis,” “tissue approximation,” and “exiting the abdomen.” Overall, the median scores in the “energy sources” and “establishment and physiology of the pneumoperitoneum” subsections were lower than in other domains. All participants agreed on the need for fundamental knowledge and a formal educational curriculum.ConclusionsCompared to experienced surgeons, surgical trainees had lesser knowledge about performing LS. Regardless of the years of experience, there are crucial knowledge gaps in specific areas regarding safe LS that should be addressed by implementing an educational curriculum.

HER2-targeted gold nanoparticles potentially overcome resistance to trastuzumab in gastric cancer

An issue of concern is that no current HER2-targeted therapeutic agent is effective against Trastuzumab (Tmab)-resistant gastric cancer. Gold nanoparticles (AuNPs) are promising drug carriers with unique characteristics of a large surface area available for attachment of materials such as antibodies. Here, we created HER2-targeted AuNPs (T-AuNPs) and examined their therapeutic efficacy and cytotoxic mechanisms using HER2-postive Tmab-resistant (MKN7) or Tmab-sensitive (NCI-N87) gastric cancer cell lines. In vitro, T-AuNPs showed stronger cytotoxic effects than controls against MKN7 and NCI-N87 cells although Tmab had no effect on MKN7 cells. Autophagy played an important role in T-AuNP cytotoxic mechanisms, which was considered to be driven by internalization of T-AuNPs. Finally, T-AuNPs displayed potent antitumor effects against NCI-N87 and MKN7 subcutaneous tumors in in vivo mouse models. In conclusion, HER2-targeted AuNPs with conjugated Tmab is a promising strategy for the development of novel therapeutic agents to overcome Tmab resistance in gastric cancer.