[OTSC-assisted resection of a duodenal neuroendocrine tumor: a case report]. / OTSC-assistierte Resektion eines neuroendokrinen Tumors im Duodenum: Ein Fallbericht.

The over the scope clip (OTSC) is mainly used for closure of gastrointestinal endoluminal defects and treatment of gastrointestinal bleeding. Its use for resection of subepithelial tumors or full-thickness resection is still under investigation. Duodenal neuroendocrine tumors (NET) are rare neoplasms. Endoscopic resection is appropriate up to a size of 20  mm, however positive deep margins are a frequent challenge in these subepithelial tumors. We report on a 60-year-old male patient who had undergone endoscopic mucosal resection with R1 deep margins of a NET (G1) in the duodenal bulb. To avoid local surgical resection in this multimorbid patient, we performed OTSC-assisted deep resection. Complete resection (R0) was achieved, and no complications occurred. Our report suggests that OTSC-assisted resection of subepithelial tumors is a possible and safe option, especially for patient's and in locations with a high perioperative risk.

In vivo molecular imaging with cetuximab, an anti-EGFR antibody, for prediction of response in xenograft models of human colorectal cancer.

BACKGROUND AND STUDY AIMS: Molecular imaging has mainly been studied for detection of lesions using diagnostic probes. The aim of the current trial was to evaluate in vivo confocal laser endomicroscopy (CLE) with cetuximab, an antibody targeting the epidermal growth factor receptor (EGFR), for detection and moreover early prediction of response to molecular chemotherapy in models of human colorectal cancer (CRC). METHODS: Xenografts with cetuximab-sensitive (HT29) and cetuximab-resistant (SW620) human CRC cell lines were induced in 44 mice. CLE was performed 48 h after injection of a fluorescently labelled cetuximab test dose, and compared with isotype antibody or untreated controls on d0, and d30 (HT29) or d15 (SW620). Initial fluorescence intensity was examined in relation to clinical readouts (tumor growth, thriving, mortality) during cetuximab treatment vs. controls. Results were validated in vivo with wide-field molecular imaging in three HT29 mice and ex vivo using fluorescence-activated cell sorting (FACS) and immunohistochemistry. RESULTS: All HT29 xenografts showed specific fluorescence in vivo after cetuximab injection on d0 and d30. Fluorescence at d0 was significantly stronger in cetuximab-treated HT29 tumors than in HT29 controls (P = 0.0017) or cetuximab-treated SW620 tumors (P = 0.0027), and accorded with significantly slower tumor progression (P = 0.0009), better overall survival (P = 0.02), and better physical condition (P < 0.0001). Cetuximab sensitivity could be predicted from fluorescence intensity at d0 with high positive predictive value. CONCLUSIONS: Molecular CLE was for the first time linked to early prediction of response to targeted therapy in models of human CRC. Therapeutic antibodies can be used as molecular beacons in CLE and wide-field techniques. These results may indicate a promising principle for early patient stratification.