Characterizations of a neutralizing antibody broadly reactive to multiple gluten peptide:HLA-DQ2.5 complexes in the context of celiac disease.

In human celiac disease (CeD) HLA-DQ2.5 presents gluten peptides to antigen-specific CD4+ T cells, thereby instigating immune activation and enteropathy. Targeting HLA-DQ2.5 with neutralizing antibody for treating CeD may be plausible, yet using pan-HLA-DQ antibody risks affecting systemic immunity, while targeting selected gluten peptide:HLA-DQ2.5 complex (pHLA-DQ2.5) may be insufficient. Here we generate a TCR-like, neutralizing antibody (DONQ52) that broadly recognizes more than twenty-five distinct gluten pHLA-DQ2.5 through rabbit immunization with multi-epitope gluten pHLA-DQ2.5 and multidimensional optimization. Structural analyses show that the proline-rich and glutamine-rich motif of gluten epitopes critical for pathogenesis is flexibly recognized by multiple tyrosine residues present in the antibody paratope, implicating the mechanisms for the broad reactivity. In HLA-DQ2.5 transgenic mice, DONQ52 demonstrates favorable pharmacokinetics with high subcutaneous bioavailability, and blocks immunity to gluten while not affecting systemic immunity. Our results thus provide a rationale for clinical testing of DONQ52 in CeD.

Exploitation of Elevated Extracellular ATP to Specifically Direct Antibody to Tumor Microenvironment.

The extracellular adenosine triphosphate (ATP) concentration is highly elevated in the tumor microenvironment (TME) and remains tightly regulated in normal tissues. Using phage display technology, we establish a method to identify an antibody that can bind to an antigen only in the presence of ATP. Crystallography analysis reveals that ATP bound in between the antibody-antigen interface serves as a switch for antigen binding. In a transgenic mouse model overexpressing the antigen systemically, the ATP switch antibody binds to the antigen in tumors with minimal binding in normal tissues and plasma and inhibits tumor growth. Thus, we demonstrate that elevated extracellular ATP concentration can be exploited to specifically target the TME, giving therapeutic antibodies the ability to overcome on-target off-tumor toxicity.

[A pilot study of TS-1+CDDP therapy for highly advanced stage IV gastric cancer].

We performed a pilot study of combination chemotherapy with TS-1 and cisplatin for highly advanced gastric cancer. From June 2002, 12 patients with multiple liver metastases, carcinomatous lymphangitis or peritoneal dissemination, were enrolled in the study. TS-1 was administered at a daily dose on day 1-21 and an intermediate-dose of cisplatin (60 mg/m2) was administered on day 8. The combination was repeated in a 5-week cycle. The median administered cycles were three (one to eight). An objective response was obtained in 9 cases (75.0%) of primary sites and 6 cases of metastatic sites. No severe hematological toxicity occurred, and grade 3 stomatitis (in one case) and vomiting (in two cases) occurred as non-hematological toxicities. The improvement of clinical symptoms such as appetite loss and abdominal discomfort was obtained in 9 of 10 cases. The median survival time is 244 days. The TS-1/CDDP regimen had almost no survival benefits, but may induce relief of symptoms due to cancer and better quality of life.

A case of small cell carcinoma of the common bile duct.

Small cell carcinoma occasionally occurs in the gastrointestinal tract, but rarely in the biliary tract. We report a case of small cell carcinoma which occurred in the common bile duct. A 66-year-old female complained of epigastralgia and weight loss. Computed tomography and ultrasonography showed a mass near the pancreas head and dilatation of the intrahepatic bile ducts. Endoscopic nasobiliary drainage was undertaken, and it revealed obstruction of the common bile duct. The patient was diagnosed preoperatively as having extrahepatic bile duct cancer. Upon laparotomy, a tumor was found to be located in the middle common bile duct. Pylorus-preserving pancreaticoduodenectomy was performed. The main trunk of the portal vein and the right hepatic artery were resected concomitantly because of tumor involvement. Postoperative pathological examination revealed well-differentiated papillary adenocarcinoma on the surface of the bile duct lumen, but a large part of the extraductal component was small cell carcinoma. Upon immunohistochemical examination, synaptophysin and chromogranin A were found to be focally positive in small cell carcinoma, but negative for L-26 and CEA. The patient then underwent two postoperative courses of systemic chemotherapy. Nevertheless, she died of cancer recurrence eight months after the operation, which showed that the tumor had a highly lethal nature, with rapid and widespread dissemination. Further therapeutic trials are needed to improve survival in such cases.

Immunohistochemical metallothionein expression in hepatocellular carcinoma: relation to tumor progression and chemoresistance to platinum agents.

BACKGROUND: Metallothionein (MT), which is known to detoxify heavy metal ions, is considered to serve as a mechanism of resistance to platinum complex compounds. In the present study, MT expression in hepatocellular carcinoma (HCC) was immunohistologically investigated to clarify its relationship to clinical background factors and responsiveness to anticancer drugs. METHODS: Specimens from 117 patients with HCC were immunohistologically studied, using a monoclonal anti-MT antibody. the percentage of MT-positive HCC (MT ratio) cells was determined, to evaluate the extent of staining with anti-MT antibody. Staining with an MT ratio of more than 50% was categorized as diffusely positive; an MT ratio of 5% to less than 50% was focally positive; and an MT ratio of less than 5% was negative. Twenty-two patients received repeated arterial infusion chemotherapy with carboplatin (CBDCA), a platinum-containing compound, and the MT expression was analyzed in relation to their chemotherapeutic response. RESULTS: The ratio of MT-positive cells in HCC decreased with the degree of histological differentiation and also decreased with higher tumor stage. In patients treated with CBDCA, the ratio of MT-positive cells in responders was significantly lower than that in non-responders. CONCLUSIONS: MT expression decreases with the degree of histological differentiation and decreases with increasing tumor stage in HCC. In addition, MT expression may lower the antitumor effect of CBDCA.