Early administration of amatuximab, a chimeric high-affinity anti-mesothelin monoclonal antibody, suppresses liver metastasis of mesothelin-expressing pancreatic cancer cells and enhances gemcitabine sensitivity in a xenograft mouse model.

Amatuximab is a promising therapeutic antibody targeting mesothelin, a 40-kDa glycoprotein that is highly expressed in pancreatic cancer. We investigated the effectiveness of early amatuximab treatment, imitating an adjuvant chemotherapy setting, and combination therapy with amatuximab and gemcitabine in liver metastasis of pancreatic cancer. Liver metastasis mouse models were established in 8-week-old male BALB/c nu/nu mice using the hemisplenic injection method. Tridaily amatuximab monotherapy or combination with gemcitabine was administered to the liver metastasis mouse model before metastatic lesions had formed huge masses. Gaussia luciferase-transfected AsPC-1 was used as a mesothelin-overexpressing pancreatic cancer cell line. The amount of liver metastases and the serum luciferase activity were significantly lower in the treatment groups than those in the control IgG group. Notably, the anti-tumor activity of gemcitabine was synergically enhanced by combination therapy with amatuximab. Furthermore, western blotting revealed that the high expression of phosphorylated c-Met and AKT in liver metastatic lesions treated with gemcitabine monotherapy was canceled by its combination with amatuximab. This result indicated that the observed synergic therapeutic effect may have occurred as a result of the inhibitory effect of amatuximab on the phosphorylation of c-Met and AKT, which were promoted by exposure to GEM. In conclusion, our study revealed that early administration of amatuximab alone or in combination with GEM significantly suppressed the liver metastases of mesothelin-expressing pancreatic cancer cells. A phase II clinical trial of amatuximab as part of an adjuvant chemotherapy regimen for resected pancreatic cancer is expected.

Mesothelin blockage by Amatuximab suppresses cell invasiveness, enhances gemcitabine sensitivity and regulates cancer cell stemness in mesothelin-positive pancreatic cancer cells.

BACKGROUND: Mesothelin is a 40-kDa glycoprotein that is highly overexpressed in various types of cancers, however molecular mechanism of mesothelin has not been well-known. Amatuximab is a chimeric monoclonal IgG1/k antibody targeting mesothelin. We recently demonstrated that the combine therapy of Amatuximab and gemcitabine was effective for peritonitis of pancreatic cancer in mouse model. METHODS: We discover the role and potential mechanism of mesothelin blockage by Amatuximab in human pancreatic cells both expressing high or low level of mesothelin in vitro experiment and peritonitis mouse model of pancreatic cancer. RESULTS: Mesothelin blockage by Amatuximab lead to suppression of invasiveness and migration capacity in AsPC-1 and Capan-2 (high mesothelin expression) and reduce levels of pMET expression. The combination of Amatuximab and gemcitabine suppressed proliferation of AsPC-1 and Capan-2 more strongly than gemcitabine alone. These phenomena were not observed in Panc-1 and MIA Paca-2 (Mesothelin low expression). We previously demonstrated that Amatuximab reduced the peritoneal mass in mouse AsPC-1 peritonitis model and induced sherbet-like cancer cell aggregates, which were vanished by gemcitabine. In this study, we showed that the cancer stem cell related molecule such as ALDH1, CD44, c-MET, as well as proliferation related molecules, were suppressed in sherbet-like aggregates, but once sherbet-like aggregates attached to peritoneum, they expressed these molecules strongly without the morphological changes. CONCLUSIONS: Our work suggested that Amatuximab inhibits the adhesion of cancer cells to peritoneum and suppresses the stemness and viability of those, that lead to enhance the sensitivity for gemcitabine.

[Locally Advanced Gastric Cancer Responding to Neoadjuvant Chemotherapy with Ramucirumab plus Paclitaxel-Case Report].

Neoadjuvant chemotherapy(NAC)is a promising approach for the improvement of gastric cancer treatment outcome. S-1 plus cisplatin(SP)or S-1 plus oxaliplatin (SOX)is generallythe first choice of NAC regimen. We experienced that NAC with ramucirumab(RAM)plus paclitaxel(PTX)was effective in locallyadvanced gastric cancer, but that with SOX was ineffective. A 68-year-old man developed locallyadvanced gastric cancer and received NAC with SOX, which was stopped because of tumor enlargement. The patient was then given NAC with RAM plus PTX, which was effective and enabled radical excision. Anti-angiogenic agents maycause wound healing complications, which mayincrease the risk of leakage. However, he was discharged without postoperative complications. Therefore, RAM plus PTX can be a promising NAC regimen for locallyadvanced gastric cancer.

Cytoplasmic CD133 expression correlates with histologic differentiation and is a significant prognostic factor in extrahepatic bile duct cancer and gallbladder cancer.

Prominin-1 (CD133) is one of the most important stem cell markers among various malignant tumor types, but the clinicopathological significance of CD133 expression in intrahepatic cholangiocarcinoma remains controversial. To the best of our knowledge, there have been no reports on extrahepatic bile duct cancer (EHBDCA) and gallbladder cancer (GBCA). The present study examined the clinicopathological significance of CD133 expression in EHBDCA and GBCA. Immunohistochemistry was used to evaluate CD133 expression in resected specimens obtained from 82 patients with EHBDCA and GBCA, and this expression was compared with the clinicopathological parameters and survival data of the patients. Cytoplasmic CD133 expression was identified in 20 patients, and its incidence was significantly associated with histopathological grade (P=0.035), pT factor (P=0.020) and recurrence (P=0.046). Survival analysis revealed that cytoplasmic CD133 expression in patients was significantly associated with a poorer overall survival (OS) and relapse-free survival (RFS) compared with those without cytoplasmic expression (5-year OS rate, 11.6% vs. 39.1%; 3-year RFS rate, 12.5% vs. 42.0%, respectively). Multivariate analysis revealed that cytoplasmic CD133 expression was an independent prognostic factor for OS and RFS (P=0.0036 and P<0.0001, respectively). To the best of our knowledge, this is the first report demonstrating that cytoplasmic CD133 expression was associated with histologic differentiation, cancer progression, recurrence and poor prognosis in EHBDCA and GBCA. CD133 expression may be a useful marker for clinical prognosis in patients with EHBDCA and GBCA.

The anti-mesothelin monoclonal antibody amatuximab enhances the anti-tumor effect of gemcitabine against mesothelin-high expressing pancreatic cancer cells in a peritoneal metastasis mouse model.

Pancreatic cancer often has a very poor prognosis, even after complete resection. The recurrence of hepatic and peritoneal metastases is an important prognostic factor; therefore, the development of improved adjuvant therapy is urgently required. Mesothelin is a cell surface glycoprotein whose expression is restricted to a variety of cancer types, including pancreatic cancer. This expression pattern makes mesothelin an attractive target for cancer therapy, and several agents targeting mesothelin are currently in clinical trials. Here, we used the chimerized high-affinity anti-mesothelin monoclonal antibody amatuximab to investigate its effect on peritoneal metastasis. We used the AsPC-1 pancreatic cancer cell line engineered to express Gaussia luciferase (Gluc), (AsPC-1-Gluc) for in vivo experiments. Results showed that while amatuximab was not directly cytotoxic on an AsPC-1-Gluc tumor cells in a peritoneal metastasis model, it prevented the formation of tumor growth. In combination therapy with gemcitabine, amatuximab exhibited synergistic killing. Our results suggest that blockade of mesothelin by amatuximab may be a useful strategy for preventing the peritoneal dissemination of pancreatic cancer under an adjuvant setting.

[A Case of Biopsy Confirmed Unresectable Retroperitoneal Seminoma Successfully Treated with Chemotherapy].

We herein report a case of a retroperitoneal tumor of unknown origin that was diagnosed as a seminoma after tumor biopsy and was successfully treated with chemotherapy containing bleomycin, etoposide, and cisplatin(BEP). A 47-year old man visited our hospital with left abdominal pain. An endoscopic examination revealed an ulcer lesion on the third part of the duodenum. Abdominal CT scan revealed a retroperitoneal tumor invading the abdominal aorta with the tumor thrombus in the inferior vena cava(IVC). An endoscopic biopsy could not identify the tumor's origin because of the negative staining of various surface markers on immunohistochemistry. Surgical biopsy of the unresectable retroperitoneal tumor that was finally diagnosed as a seminoma was performed. The patient was treated with BEP according to the International Germ Cell Consensus Classification(IGCCC)for risks, and orchiectomy was performed. He has been alive for 7 months with progressive shrinkage of the retroperitoneal tumor, in which 18F-fluorodeoxyglucose(FDG)positron emission tomography(PET)has shown a dramatic reduction of the maximum standardized uptake value(SUV)during chemotherapy.

Clinical impacts of mesothelin expression in gastrointestinal carcinomas.

Mesothelin, C-ERC/mesothelin is a 40-kDa cell surface glycoprotein that is normally present on normal mesothelial cells lining the pleura, peritoneum, and pericardium. Moreover, mesothelin has been shown to be overexpressed in several human cancers, including virtually all mesothelioma and pancreatic cancer, approximately 70% of ovarian cancer and extra bile duct cancer, and 50% of lung adenocarcinomas and gastric cancer. The full-length human mesothelin gene encodes the primary product, a 71-kDa precursor protein. The 71-kDa mesothelin precursor is cleaved into two products, 40-kDa C-terminal fragment that remains membrane-bound via glycosylphosphatidylinositol anchor, and a 31-kDa N-terminal fragment, megakaryocyte potentiating factor, which is secreted into the blood. The biological functions of mesothelin remain largely unknown. However, results of recent studies have suggested that the mesothelin may play a role of cell proliferation and migration. In pancreatic cancer, mesothelin expression was immunohistochemically observed in all cases, but absent in normal pancreas and in chronic pancreatitis. Furthermore, the expression of mesothelin was correlated with an poorer patient outcome in several human cancers. The limited mesothelin expression in normal tissues and high expression in many cancers makes it an attractive candidate for cancer therapy. The present review discusses the expression and function of mesothelin in cancer cells and the utility of mesothelin as a target of cancer therapy.

Immunohistochemical analysis of cancer stem cell markers in pancreatic adenocarcinoma patients after neoadjuvant chemoradiotherapy.

BACKGROUND: Cancer stem cells (CSCs) have been reported to play an important role in chemoradiation resistance. Although the association of CSC markers with clinicopathological outcomes after neoadjuvant chemoradiotherapy (NACRT) has been reported in various types of cancers, there have been no such reports for pancreatic cancer. Here we examined the sequential changes in CSC marker expressions after NACRT in patients with pancreatic adenocarcinoma (PA) and the impact of these changes on the prognosis. METHODS: We used immunohistochemistry to evaluate the expressions of the CSC markers epithelial cell adhesion molecule (EpCAM), CD24, CD44, CD133, CXCR4 and Aldehyde dehydrogenase 1 (ALDH1) in resected specimens obtained from 28 PA patients, and we compared these expressions with the patients' clinicopathological parameters and survival data. RESULTS: The expression frequencies of CD44 and ALDH1 were significantly higher in the NACRT group (n = 17) compared to the non-NACRT group (n = 11), but the CD133 expression was significantly lower in the NACRT group. In the NACRT group, the expression of CD133 was inversely correlated with that of ALDH1, and CD133+/ALDH1- expression was associated with an unfavorable patient outcome. CONCLUSION: This is the first report showing that NACRT may influence the expression frequencies of CD44, CD133 and ALDH1 in PA patients. Moreover, CD133 and ALDH1 expressions may be useful predictors of prognosis in PA patients who have received NACRT.

Chylous ascites caused by resection of a choledochal cyst.

Chylous ascites is a rare complication of abdominal surgery in children. Particularly, reports of postoperative chylous ascites are rare. This report describes the very rare case of a 10-month-old girl complicated by chylous ascites after resection of a choledochal cyst with a Roux-en-Y hepaticojejunostomy, who was successfully treated medically. To date, we have found a few cases of postoperative chylous ascites in the paediatric literature. To the best of our knowledge, this is the first report of chylous ascites after the resection of a choledochal cyst in a child who was successfully treated solely by no fasting. No fasting might be a therapeutic option of paediatric postoperative chylous ascites after the resection of a choledochal cyst if the outflow volume of chylous ascites is small.

[A successful case of systemic chemotherapy followed by liver resection for advanced hepatocellular carcinoma with highly vascular invasion and multiple pulmonary metastases].

The prognosis for hepatocellular carcinoma with extrahepatic metastasis or vascular invasion is very poor. We treated a case successfully by combining chemotherapy and liver resection for hepatocellular carcinoma with multiple pulmonary metastases and vascular invasion. A 56-year-old man who complained of abdominal pain in his right side was transported to the hospital by ambulance. Because CT scan revealed the rupture of hepatocellular carcinoma, he underwent emergency transcatheter arterial embolization (TAE). A close examination revealed tumor thrombus in the inferior vena cava and posterior segment of the portal vein branch, with multiple pulmonary metastases. We conducted right hepatic lobectomy and removal of the inferior vena cava tumor thrombus. After the operation, pulmonary metastatic lesions gradually grew larger, so the oral administration of S-1 at 120 mg per day was started. At the end of the first course, the CT scan revealed that multiple pulmonary metastases were significantly reduced, and treatment was maintained until the end of 4 courses. A prolongation of survival could be expected by combining systemic chemotherapy and liver resection for advanced hepatocellular carcinoma such as the present case.