Vascular endothelial growth factor (VEGF) plays a key role in tumor angiogenesis by stimulating the proangiogenic signaling of endothelial cells via activation of VEGF receptor (VEGFR) tyrosine kinases. Therefore, VEGFRs are an attractive therapeutic target for cancer treatment. In the present study, we show that a quinoline-urea derivative, KRN951, is a novel tyrosine kinase inhibitor for VEGFRs with antitumor angiogenesis and antigrowth activities. KRN951 potently inhibited VEGF-induced VEGFR-2 phosphorylation in endothelial cells at in vitro subnanomolar IC 50 values (IC 50 = 0.16 nmol/L). It also inhibited ligand-induced phosphorylation of plateletderived growth factor receptor-B (PDGFR-B) and c-Kit (IC 50 = 1.72 and 1.63 nmol/L, respectively). KRN951 blocked VEGFdependent, but not VEGF-independent, activation of mitogenactivated protein kinases and proliferation of endothelial cells. In addition, it inhibited VEGF-mediated migration of human umbilical vein endothelial cells. Following p.o. administration to athymic rats, KRN951 decreased the microvessel density within tumor xenografts and attenuated VEGFR-2 phosphorylation levels in tumor endothelium. It also displayed antitumor activity against a wide variety of human tumor xenografts, including lung, breast, colon, ovarian, pancreas, and prostate cancer. Furthermore, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) analysis revealed that a significant reduction in tumor vascular hyperpermeability was closely associated with the antitumor activity of KRN951. These findings suggest that KRN951 is a highly potent, p.o. active antiangiogenesis and antitumor agent and that DCE-MRI would be useful in detecting early responses to KRN951 in a clinical setting. KRN951 is currently in phase I clinical development for the treatment of patients with advanced cancer. (Cancer Res 2006; 66(18): 9134-42)

Purpose: Endosialin/CD248/tumor endothelial marker 1is expressed in stromal cells, endothelial cells, and pericytes in various tumors; however, few studies have focused on expression in malignant cells. Experimental Design: We studied expression of endosialin in clinical specimens, cell culture, and animal models and designed an anti-endosialin therapeutic prototype. Results: Fifty human tumor cell lines and 6 normal cell types in culture were assayed by reverse transcription-PCR and/or flow cytometry for endosialin. Cell surface protein was found on 7 sarcoma lines, 1neuroblastoma, and 4 normal cell types in culture. A fully human anti-endosialin antibody bound to human A-673 Ewing's sarcoma cells and SK-N-AS neuroblastoma cells but not HT-1080 cells. Exposure of cells to an anti-human IgG conjugated to saporin resulted in growth inhibition only of endosialin-expressing cells. Endosialin expression was assessed by immunohistochemistry in 250 clinical specimens of human cancer including 20 cancer subtypes. Endosialin is frequently found in human cancers. Endosialin expression is mainly a perivascular feature in carcinomas, with some expression in stromal cells. In sarcomas, endosialin is expressed by malignant cells, perivascular cells, and stromal cells. Development and characterization of experimental models for studying endosialin biology in sarcomas and evaluating anti-endosialin therapies is presented. Conclusions: Findings suggest that an anti-endosialin immunotoxin might be a promising therapeutic approach for endosialin-positive neoplasia, especially synovial sarcoma, fibrosarcoma, malignant fibrous histiocytoma, liposarcoma, and osteosarcoma. Thus, a diagnostic/therapeutic targeted therapeutic approach to treatment of endosialin-expressing tumors may be possible.

N-Phenyl-N'-{4-(4-quinolyloxy)phenyl}ureas were found to be a novel class of potent inhibitors for the vascular endothelial growth factor receptor 2 (VEGFR-2) tyrosine kinase through synthetic modifications of a lead compound and structure-activity relationship studies. A representative compound 6ab, termed Ki8751, inhibited VEGFR-2 phosphorylation at an IC(50) value of 0.90 nM, and also inhibited the PDGFR family members such as PDGFRalpha and c-Kit at 67 nM and 40 nM, respectively. However, 6ab did not have any inhibitory activity against other kinases such as EGFR, HGFR, InsulinR and others even at 10000 nM. 6ab suppressed the growth of the VEGF-stimulated human umbilical vein endothelial cell (HUVEC) on a nanomolar level. 6ab showed significant antitumor activity against five human tumor xenografts such as GL07 (glioma), St-4 (stomach carcinoma), LC6 (lung carcinoma), DLD-1 (colon carcinoma) and A375 (melanoma) in nude mice and also showed complete tumor growth inhibition with the LC-6 xenograft in nude rats following oral administration once a day for 14 days at 5 mg/kg without any body weight loss.

10519 Background: Targeting of HER2 with trastuzumab (T) is a well-established strategy in the metastatic and adjuvant setting in HER2 positive breast cancer (HER2-BC). Although HER2 status is routinely determined using immunohistochemistry or fluorescence in situ hybridization, technical problem can arise when lesions are poorly accessible. HER2 expression can vary during the course of the disease, and there can be discordance in HER2 expression across tumor lesion even in the same patients. Noninvasive HER2 imaging is crucial needed to solve these problems. Previous imaging using 111In or 89Zn- trastuzumab produced high radiation exposure to patients by their long half life (=67.9and 78.4h) and low resolution image. Half life of 64Cu is 12.7h. We performed a feasibility study of the 64Cu-1, 4, 7, 10- tetraazacylododecane-N,N',N",N"'-tetraacetic acid (DOTA)-T to perform PET imaging in patients with HER2-BC. Methods: Patients with HER2-BC received 150 MBq of 64Cu-DOTA-T and underwent PET scan 1, 24 and 48h after the injection. Six patients were evaluated internal dosimetry by collecting radioactivity data of blood and normal tissue in each time point from PET study, and radiation exposure by collecting clothes, linen and urine to test feasibility for outpatients. Results: Fifteen patients who received T therapy were enrolled in the “first-in-human” trial. All patients had no severe toxicity. Radiation excretion evaluating clothes, linen were under background level. Radiation exposure of 64Cu-DOTA-T was equivalent to that of conventional 18F-FDG-PET. Distribution of liver, kidney, spleen, and blood vessel was 2-8 SUV, and uptake in other normal tissue was low. At visual examination, in two patients brain metastases were clearly visualized by 64Cu-DOTA-T-PET, suggesting that there are disruptions of the blood-brain barrier at the site of the brain metastases. The sternum bone metastasis was well visualized and quantitatively monitored according to the response by T. Primary breast cancers, lymph node metastases and lung metastases could also be visualized at the lesion indentified by CT. Conclusions: 64Cu-DOTA-T-PET was feasible test even for outpatient, and provides specific and high resolution image in HER2 positive lesion.

We have previously established a concept of developing exogenic pancreas in a genetically modified pig fetus with an apancreatic trait, thereby proposing the possibility of in vivo generation of functional human organs in xenogenic large animals. In this study, we aimed to demonstrate a further proof-of-concept of the compensation for disabled organogeneses in pig, including pancreatogenesis, nephrogenesis, hepatogenesis, and vasculogenesis. These dysorganogenetic phenotypes could be efficiently induced via genome editing of the cloned pigs. Induced dysorganogenetic traits could also be compensated by allogenic blastocyst complementation, thereby proving the extended concept of organ regeneration from exogenous pluripotent cells in empty niches during various organogeneses. These results suggest that the feasibility of blastocyst complementation using genome-edited cloned embryos permits experimentation toward the in vivo organ generation in pigs from xenogenic pluripotent cells.

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Infusion reactions are a major side effect of the administration of therapeutic Abs and are the result of a complex immune reaction. In this study, we report that substitutions of Fc amino acids in the anti-HLA-DR Ab HD8 reduce its ability to induce infusion reactions in rats and monkeys. We first showed that i.v. administration of IgG1- and IgG2-subclass HD8 Abs induces severe infusion reactions in monkeys. These Abs express strong complement-dependent cytotoxicity (CDC), and in vivo depletion of complement in rats by pretreatment with cobra venom factor abrogated the lethal infusion reactions generated by HD8-IgG1. Thus, the infusion reactions appear to be largely driven by the complement system. To reduce the CDC function of HD8-IgG1, its Fc region was modified by two amino acid substitutions at Pro331Ser and Lys322Ala. The modified Ab was incapable of expressing CDC in vitro and did not induce severe infusion reactions in rats and monkeys, even at extremely high doses. The modified Ab retained its Ab-dependent cellular cytotoxicity function as well as its antitumor activity in a tumor-bearing mouse model. In summary, complement appears to drive infusion reactions, and modifications that eliminate the CDC activity of an Ab also reduce its ability to induce infusion reactions.

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