Naoto Hori

Training system for laparoscopy-assisted distal gastrectomy

PurposeLaparoscopy-assisted distal gastrectomy (LADG) is likely to become a standard procedure for gastric cancer, which highlights the importance of establishing a training system in which even inexperienced surgeons can perform this procedure safely. This study assesses our training system for LADG based on short-term surgical outcomes.MethodsWe evaluated retrospectively the short-term outcomes of 100 consecutive LADGs with curative D1/D1+ lymph node dissection. Our training system was assessed based on the learning curve of trainees, and factors related to achieving good-quality operations were analyzed statistically.ResultsOverall, postoperative complications developed in 10 patients (10%), and included one case of anastomotic leakage (1%) and one case of pancreatic fistula (1%). The learning curve of the trainees plateaued after 10 operator cases in terms of operation time. The importance of the trainer’s position was also confirmed by the result that the operation time was significantly longer when trainees with ≤10 operator cases performed LADG with a trainer as scopist vs. a trainer as the first assistant. Univariate and multivariate analyses revealed that >10 operator cases were the most important factor for achieving good-quality operations.ConclusionThese results show that our current LADG procedure and training system are appropriate and effective.

Abstract 3412: Virus-guided fluorescence imaging of intraperitoneal free gastric cancer cells: a preliminary clinical study as a potential clinical biomarker

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Objectives: In patients with gastric cancer, peritoneal dissemination is the most common metastasis. To predict future peritoneal recurrences, peritoneal lavage cytology is performed during operation. But even cytology-negative patients sometimes develop peritoneal recurrences. Thus an additional method to detect intraperitoneal free gastric cancer cells is necessary. We have developed a genetically engineered adenovirus, TelomeScan, which replicates and expresses GFP only in telomerase-activated cancer cells. Here we detected intraperitoneal free gastric cancer cells using TelomeScan, and investigated the correlation between the number of GFP-positive cells and patient prognosis. Methods: Peritoneal wash was obtained from 69 gastric cancer patients during operation. The cells in the wash were infected with TelomeScan for 24 hours. Finally, GFP-positive cells were counted under a fluorescence microscope. In some GFP-positive cases immunofluorescence assay was added. Clinicopathological data were obtained from medical records. Then we examined different cut-off values (the number of GFP-positive cells which indicates TelomeScan-positive) and estimated survival curves using the Kaplan-Meier method, and compared using the Wilcoxon test. Results: For a cut-off value of 10, 25 of the 69 cases were TelomeScan-positive (10 or more GFP-positive cells). And these 25 cases showed the most significant worse prognosis when compared to the 44 TelomeScan-negative cases (p = 0.0040). In addition, 17 of the 69 cases were conventional cytology-positive. Of these 17 cases, 9 were TelomeScan-positive, and these 9 cases showed significantly worse prognosis than the 8 TelomeScan-negative conventional cytology-positive cases (p = 0.0017, MST 195 days). Under fluorescence microscope we observed that GFP-positive cells sometimes formed cell clusters with GFP-negative cells. Immunofluorescence assay showed that these GFP-negative cells expressed CD45, which means these cells were leukocytes. Conclusion: We have successfully detected cancer cells in peritoneal wash using TelomeScan. The presence of GFP-positive cells in peritoneal wash was associated with worse prognosis. TelomeScan-positive patients, especially in conventional cytology-positive cases, showed remarkably worse prognosis than TelomeScan-negative conventional cytology-positive patients. Our data suggest that TelomeScan-guided cytological detection may have clinical implications as a prognostic biomarker in gastric cancer. Citation Format: Megumi Watanabe, Shunsuke Kagawa, Kazuya Kuwata, Michihiro Ishida, Yuuri Hashimoto, Naoto Hori, Satoru Kikuchi, Shinji Kuroda, Hiroyuki Kishimoto, Masahiko Nishizaki, Hiroshi Tazawa, Yasuo Urata, Toshiyoshi Fujiwara. Virus-guided fluorescence imaging of intraperitoneal free gastric cancer cells: a preliminary clinical study as a potential clinical biomarker. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3412. doi:10.1158/1538-7445.AM2015-3412

Abstract 3535: A novel tumor-specific oncolytic biological therapy against invasive pancreatic cancer

Pancreatic cancer is one of the worst prognosis disease all over the world and has an overall 5-year survival rate of less than 5%. At the time of diagnosis, more than 80% of patients are not eligible for curative surgical resection due to extensive local tumor invasion and early systemic metastasis. Moreover, even after curative surgery, pancreatic cancers still show poor prognosis due to local recurrence and systemic metastasis. Gemcitabine is the standard chemotherapeutic agent to treat advanced pancreatic cancers, but median overall survival ranged from 5.0 to 7.2 months, suggesting that standard chemotherapy is less effective to most of pancreatic cancer patients. Therefore, the development of novel therapeutic strategy is needed for the treatment of pancreatic cancers. We developed a novel oncolytic adenovirus, OBP-702, in which a human telomerase reverse transcriptase gene promoter drives viral E1 gene for virus replication, and armed with the wild-type tumor suppressor p53 gene. Precise antitumor effects of OBP-702 have been evaluated in human pancreatic cancer cells. We used four pancreatic cancer cell lines with different invasion ability, including non-invasive type (MIA PaCa-2, Panc-1) and invasive type (BxPC-3, Capan-1). The antitumor effect of OBP-702 for each cell line was assessed using XTT assay. OBP-702 induced profound anti-tumor effect in all human pancreatic cancer cells, whereas OBP-301 lacking the p53 tumor suppressor gene showed differential effects among the cell types. OBP-301 induced moderate anti-tumor effect in MIA Paca-2, BxPC-3 and Capan-1 cells and strong anti-tumor effect in Panc-1 cells in a dose-dependent manner, suggesting the broad spectrum of OBP-7029s efficacy. The molecular mechanism of anti-tumor effect was assessed by Western blot analysis. OBP-301 induced autophagy-related cell death, whereas OBP-702 induced autophagy- and apoptosis-related cell deaths. These results suggest that an oncolytic adenovirus, OBP-702, is a promising antitumor agent to induce profound cell death in invasive human pancreatic cancer cells. The clinical trial of intratumoral administration of OBP-702 in patients with invasive pancreatic cancer is warranted. Citation Format: Takeshi Koujima, Hiroshi Tazawa, Naoto Hori, Shuta Tamura, Shinji Kuroda, Hiroyuki Kishimoto, Masahiko Nishizaki, Yasuo Urata, Shunsuke Kagawa, Toshiyoshi Fujiwara. A novel tumor-specific oncolytic biological therapy against invasive pancreatic cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3535. doi:10.1158/1538-7445.AM2015-3535

Abstract 3531: Companion diagnostics-based telomerase-specific oncolytic virotherapy: preclinical evaluation in human colorectal cancer cell lines differentially affected in the RAS/RAF/MEK signaling pathway

Colorectal cancers harboring KRAS or BRAF mutations often show resistance to anti-cancer drugs, and are poor prognostic disease that causes metastasis and recurrence compared to those with wild type KRAS and BRAF. KRAS/BRAF-wild type colorectal cancers are sensitive to both cetuximab and panitumumab that are epidermal growth factor receptor (EGFR)-targeting agents. However, KRAS/BRAF-mutant colorectal cancers are resistant to EGFR-targeting agents because of constitutive activation of the EGFR-downstream RAS/RAF/MEK signaling pathway. Therefore, the development of novel therapeutic strategy is required to improve the clinical outcome in patients with KRAS/BRAF-mutant colorectal cancers. We developed two types of telomerase-specific replication-competent oncolytic adenoviruses, OBP-301 and OBP-702 armed with the wild-type p53 tumor suppressor gene. In this study, we established the companion diagnostics-based selection algorithm for our oncolytic viruses. We compared the antitumor effects of OBP-301 and OBP-702 in human colorectal cancer cells with wild type KRAS/BRAF (SW48, Colo320DM), mutated KRAS (DLD-1, SW620) and mutated BRAF (RKO, HT29). We evaluated the antitumor effect of OBP-301 and OBP-702 in human colorectal cancer cells using XTT assay. Oncolytic adenovirus-mediated induction of apoptosis- and autophagy-related cell death was analyzed by Western blot analysis. KRAS-mutant colorectal cancer cells were sensitive to both OBP-301 and OBP-702 as well as KRAS/BRAF-wild type cells. In contrast, BRAF-mutant colorectal cancer cells were sensitive to OBP-702 rather than OBP-301. Western blot analysis showed that OBP-301 induced autophagy, whereas OBP-702 induced both autophagy and apoptosis. Taken together, our data suggest that oncolytic viruses should be used according to the genetic background of the RAS/RAF/MEK signaling pathway, especially in patients with colorectal cancer. Citation Format: Shuta Tamura, Hiroshi Tazawa, Naoto Hori, Takeshi Koujima, Satoru Kikuchi, Shinji Kuroda, Hiroyuki Kishimoto, Takeshi Nagasaka, Masahiko Nishizaki, Yasuo Urata, Shunsuke Kagawa, Toshiyoshi Fujiwara. Companion diagnostics-based telomerase-specific oncolytic virotherapy: preclinical evaluation in human colorectal cancer cell lines differentially affected in the RAS/RAF/MEK signaling pathway. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3531. doi:10.1158/1538-7445.AM2015-3531

Strategic approach to concurrent aberrant left gastric vein and aberrant left hepatic artery in laparoscopic distal gastrectomy for early gastric cancer: A case report.

An aberrant left gastric vein (ALGV) directly entering the lateral segment of the liver is a rare variation in the portal vein system, whereas an aberrant left hepatic artery (ALHA) arising from the left gastric artery is observed relatively frequently. Here we report a case in which both ALGV and ALHA were encountered before laparoscopic distal gastrectomy with curative lymphadenectomy for gastric cancer. We accurately diagnosed these vessel anomalies preoperatively on abdominal contrast‐enhanced CT. During surgery, we divided the ALGV at the point of entry to the liver and preserved the ALHA by dividing the branches toward the stomach, in consideration of curability and safety. The postoperative course was uneventful overall, although temporary mild liver dysfunction was observed. This case highlights the importance of preoperative evaluation and preparation in a rare case of concurrent ALGV and ALHA.

Abstract 4726: Virus-guided fluorescence imaging of intraperitoneal free gastric cancer cells as a potential clinical biomarker

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Peritoneal dissemination is a common pattern of metastasis in patients with gastric cancer, and associated with worse prognosis. Peritoneal lavage cytology during the operation is an important factor in predicting future development of peritoneal metastasis and determining the treatment strategy, but its sensitivity and specificity are unsatisfactory. TelomeScan is an adenovirus engineered to replicate and express GFP only in telomerase-activating tumor cells, so that we can easily detect viable cancer cells even among numerous normal cells. We hypothesized that TelomeScan might be applicable to detecting free cancer cells in peritoneal wash. Methods: Peritoneal washes were obtained from 42 gastric cancer patients during operation. The number of GFP-positive cells was determined for each sample and compared with cytology results and clinicopathological data Results: Clinical stage was ranged from IA to IV, and thirteen cases were diagnosed as class IV or class V by peritoneal lavage cytology. More than 10 GFP-positive cells were detected in 12 out of 42 cases, and these cases showed a worse prognosis when compared to the other 30 cases. Conclusion: We were able to detect gastric cancer cells as GFP-positive cells in peritoneal wash using TelomeScan. Furthermore, the presence of GFP-positive cells in peritoneal wash was associated with worse prognosis. These results suggest that number of cancer cells detected by TelomeScan in the peritoneal wash may have important clinical implication as prognostic and therapeutic biomarkers in gastric cancer. Citation Format: Megumi Watanabe, Shunsuke Kagawa, Michihiro Ishida, Naoto Hori, Satoru Kikuchi, Shinji Kuroda, Hiroyuki Kishimoto, Masahiko Nishizaki, Hiroshi Tazawa, Toshiyoshi Fujiwara. Virus-guided fluorescence imaging of intraperitoneal free gastric cancer cells as a potential clinical biomarker. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4726. doi:10.1158/1538-7445.AM2014-4726

Abstract 4025: Combination strategy of endoscopic resection and telomerase-targeting oncolytic virus for eradicating lymph node metastasis of submucosal invasive colorectal cancer

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Endoscopic resection is now one of the options as minimally invasive therapy for early colorectal cancer, However, surgical resection has been still standard for submucosal invasive colorectal cancer, because about 10% of that have LN metastasis. To secure endoscopic resection for submucosal invasive colorectal cancer, an alternative, innovational strategy to purge potential LN metastasis is required. We previously reported that a telomerase-dependent oncolytic adenovirus (OBP-301) spreads to the regional LNs, selectively replicates, and eradicates metastatic cancer cells in LNs, when administered into the orthotopically xenotransplanted rectal tumor in mouse model. In this study we evaluated whether OBP-301 could inhibit LN metastasis after the local resection mimicking endoscopic resection in a submucosal invasive rectal tumor mouse model. Human colon cancer HCT-116 cells expressing green fluorescent protein (GFP) were orthotopically implanted into the submucosal layer of the rectum in nude mouse, to develop resultant rectal tumor mimicking submucosal invasive one. LN metastasis was observed in 78.5% of mice as early as 7 days after cancer cell inoculation. The rectal tumor was injected with OBP-301 peritumorally, and then got locally excised mimicking Endoscopic submucosal dissection (ESD) technique. Seven days after tumor resection, the treatment with OBP-301 showed a significant inhibition in LN metastasis, whereas the other control treatment did not. Moreover, LN metastatic recurrence was not detected in OBP-301-treated group even 4 weeks after tumor resection. Similar results were also observed in another model with human colon cancer Colo-205-GFP cells. These results suggest that a novel combination of ESD and OBP-301 might have potential to take place of the conventional surgical approach in treating submucosal invasive colorectal cancer. Citation Format: Naoto Hori, Satoru Kikuchi, Hiroyuki Kishimoto, Hiroshi Tazawa, Yuuri Hashimoto, Shinji Kuroda, Shunsuke Kagawa, Yasuo Urata, Robert M. Hoffman, Toshiyoshi Fujiwara. Combination strategy of endoscopic resection and telomerase-targeting oncolytic virus for eradicating lymph node metastasis of submucosal invasive colorectal cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4025. doi:10.1158/1538-7445.AM2014-4025