Pramila Paudyal

Positron emission tomography imaging and biodistribution of vascular endothelial growth factor with 64Cu-labeled bevacizumab in colorectal cancer xenografts.

Vascular endothelial growth factor (VEGF) is considered to be a major angiogenic factor responsible for the development of tumor vasculature. The aim of this study was to image VEGF expression with 64Cu‐labeled anti‐VEGF antibody (bevacizumab) non‐invasively, and to see whether or not the expression was correlated with tumor accumulation in colorectal cancer xenografts. Bevacizumab was conjugated with the bifunctional chelator 1, 4, 7, 10‐tetraazacyclododecane‐1, 4, 7, 10‐tetraacetic acid (DOTA) and radiolabeled with 64Cu. In vivo biodistribution studies and positron emission tomography (PET) imaging were performed on mice bearing human colorectal cancer (HT29) xenografts after injection of 64Cu‐DOTA‐bevacizumab, which showed clear accumulation of 64Cu‐DOTA‐bevacizumab in the tumor (22.7 ± 1.0 %ID/g, 24 ± 0.2 %ID/g, 19.0 ± 2.5 %ID/g at 24, 48 and 72 h, respectively). Tumor accumulation of 64Cu‐DOTA‐bevacizumab was significantly correlated with VEGF expression as measured by western blot (ρ = 0.81, P = 0.004). Vascular endothelial growth factor blocking with unlabeled bevacizumab significantly reduced tumor accumulation of 64Cu‐DOTA‐ bevacizumab (9.7 ± 1.2 %ID/g, P < 0.001) at 48 h. Interestingly, the blood concentration of VEGF in the mice treated with excess fold of bevacizumab was significantly higher than those without at 48 h (25.5 ± 4.6 %ID/g vs 6.5 ± 2.1 %ID/g, P = 0.0016). Liver uptake decreased from 24 h (17.2 ± 1.7 %ID/g) to 48 h (13.0 ± 4.2 %ID/g) and 72 h (10.6 ± 1.5 %ID/g) due to hepatic clearance of the tracer. The present study successfully showed 64Cu‐DOTA‐bevacizumab as a potential PET tracer for non‐invasive imaging of VEGF expression in colorectal cancer xenografts. (Cancer Sci 2011; 102: 117–121)

Expression of glucose transporters and hexokinase II in cholangiocellular carcinoma compared using [18F]-2-fluro-2-deoxy-D-glucose positron emission tomography.

Cholangiocellular carcinoma (CCC) has been reported to have a high glucose uptake; however, the mechanism of glucose entry into these cells is still unclear. We investigated the relationship between [18F]‐2‐fluro‐2‐deoxy‐d‐glucose (18F‐FDG) uptake and the expression of facilitative glucose transporters (Glut) and hexokinase (HK) II, as well as the association between the expression of different histological types of CCC. The expression of Glut (1–5) and HK II was studied using immunohistochemistry of 26 patients with CCC who underwent whole‐body 18F‐FDG positron emission tomography before surgery or biopsy. CCC expressed immunohistochemically detectable Glut 1 in 81%, Glut 2 in 54%, Glut 3 in 19%, and HK II in 77% of the total cases. Glut 1, Glut 2, Glut 3, and HK II were more often detected in moderately differentiated and poorly differentiated than in well‐differentiated CCC. A significant correlation was observed between 18F‐FDG uptake and the staining scores of Glut 1 and HK II (P = 0.02, ρ = 0.45 and P = 0.001, ρ = 0.59). The staining scores of Glut 1 and HK II were also significantly correlated (P = 0.002, ρ = 0.3). Multivariate regression analysis revealed that lymph‐node metastasis was independently associated with 18F‐FDG uptake. Our study showed a significant association between the expression of Glut 1 and HK II with 18F‐FDG uptake, indicating that Glut 1 is a major glucose transporter expressed in CCC and that HK II contributes to the increased metabolism of glucose, especially in moderately and poorly differentiated CCC. (Cancer Sci 2008; 99: 260–266)

Imaging and biodistribution of Her2/neu expression in non-small cell lung cancer xenografts with 64Cu-labeled trastuzumab PET

Non‐small cell lung carcinomas (NSCLC) overexpress the Her2/neu gene in approximately 59% of cases. Trastuzumab, a humanized monoclonal antibody, interferes with Her2 signaling and is approved for the treatment of Her2/neu overexpressing breast cancer. However, its therapeutic use in Her2/neu overexpressing NSCLC remains obscure. The present study aimed to determine the role of 64Cu‐labeled trastuzumab positron emission tomography (PET) for non‐invasive imaging of Her2/neu expression in NSCLC. Trastuzumab was conjugated with the bifunctional chelator 1, 4, 7, 10‐tetraazacyclododecane‐1, 4, 7, 10‐tetraacetic acid (DOTA) and radiolabeled with 64Cu. The molecular specificity of DOTA‐trastuzumab was determined in NSCLC cell lines with Her2/neu overexpression (NCI‐H2170) and negative expression (NCI‐H520). Imaging of Her2/neu expression was performed in NCI‐H2170 tumor‐bearing mice with 64Cu‐DOTA‐trastuzumab PET and 64Cu‐DOTA‐IgG. In vitro studies revealed specific binding of DOTA‐trastuzumab in the Her2/neu positive NCI‐H2170 cells, while no binding was seen in the Her2/neu negative NCI‐H520 cell line. Biodistribution and PET studies revealed a significantly high accumulation of 64Cu‐DOTA‐trastuzumab in the Her2/neu overexpressing NCI‐H2170 tumor at 24 and 48 h post‐injection (21.4 ± 1.4% and 23.2 ± 5.1% injection dose/gram (% ID/g), respectively). PET imaging of Her2/neu negative NCI‐H520 tumors showed much less uptake of 64Cu‐DOTA‐trastuzumab (4.0% ID/g). The NCI‐H2170 tumor uptake of 64Cu‐DOTA‐trastuzumab was significantly higher than that of 64Cu‐DOTA‐IgG (P < 0.0001). 64Cu‐DOTA‐trastuzumab showed a very clear image of a Her2/neu positive tumor and appeared to be effective as a PET tracer for imaging of Her2/neu gene expression in NSCLC, suggesting its potential clinical use for identifying patients that might benefit from trastuzumab‐based therapy.

Clinicopathological presentation of varying 18F-FDG uptake and expression of glucose transporter 1 and hexokinase II in cases of hepatocellular carcinoma and cholangiocellular carcinoma

We report the results of 18F-fluorodeoxyglucose positron emission tomography (FDG PET) and immunohistochemical staining of glucose transporter 1 (Glut-1) and hexokinase II (HK-II) in patients with hepatocellular carcinoma (HCC) and cholangiocellular carcinoma (CCC) to observe the variation in 18F-FDG uptake and variation in expression of Glut-1 and HK-II in these hepatic tumors. In the case of HCC, moderate 18F-FDG uptake and strong expression of HK-II were detected, whereas Glut-1 was not expressed. Conversely, CCC showed high 18F-FDG uptake and increased expression of Glut-1 but HK-II was not expressed. The variation in the 18F-FDG uptake and expression of Glut 1 and HK-II in HCC and CCC might be owing to the difference in origin and the different mechanisms involved in glucose uptake, rate of glucose transporters, and hexokinase activity involved in the glycolytic pathway.

A Case Report of Acute Renal Failure Associated With Bee Pollen Contained in Nutritional Supplements

We report a case of renal failure associated with the ingestion of bee pollen containing nutritional supplement. A 49‐year‐old male patient who had been ingesting a nutritional supplement for more than five months had breathing difficulties, anuria, exceptional weight gain (20 kg) due to systemic edema, and loss of appetite. A renal biopsy confirmed interstitial nephritis with the presence of eosinophils, which is suggestive of drug‐induced acute renal failure. The nutritional supplement was ceased and hemodialysis begun. The patients condition improved after several hemodialysis sessions, which were then stopped. Current information regarding the adverse effects of bee pollen is not very robust, therefore potential damage should be kept in mind before ingesting nutritional supplements in which it is contained. This report serves as an important reminder to the public as well as healthcare providers of the potential of renal failure related to nutritional supplements.