Molecular imaging with a fluorescent antibody targ

Authors: Aram S A van Brussel Arthur Adams Jeroen F Vermeulen Sabrina Oliveira Elsken van der Wall Willem P Th M Mali Paul J van Diest Paul M P van Bergen en Henegouwen

Publish Date: 2013/07/17

Volume: 140, Issue: 2, Pages: 263-272

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Abstract

Ductal carcinoma in situ DCIS of the breast is difficult to remove completely during surgery as it is not palpable and can therefore require reexcision Realtime visualization of DCIS using nearinfrared fluorescent probes could help the surgeon during surgery as well as the pathologist postoperatively to distinguish the tumor from healthy tissue As hypoxiainduced necrosis is a common phenomenon in DCIS we investigated the molecular imaging of DCIS using a fluorescent antibody targeting a hypoxia marker carbonic anhydrase IX CAIX in a preclinical mouse model A monoclonal antibody against human CAIX was fluorescently labeled with the nearinfrared dye IRDye800CW and characterized in vitro An in vivo study was performed in SCID/Beige mice that were orthotopically transplanted with human breast cancer cells mimicking human DCIS MCF10DCIS and MCF10DCIS stably expressing CAIX A clinically approved fluorescence imaging system was used to monitor probe uptake and to determine tumortonormal tissue ratios TNR Mean in vivo TNR of CAIXtransduced CAIX+ tumors was 75 ± 05 Mean in vivo TNR of DCIS tumors with hypoxic areas reached a plateau level at 48 h after injection of 21 ± 01 mean ± SEM compared to 17 ± 01 in DCIS without hypoxic areas Mean intraoperative TNR of DCIS tumors with necrotic regions was higher than that of DCIS tumors without necrotic regions 96 h after injection—29 ± 01 and 15 ± 01 respectively—while the TNR of CAIX+ tumors was 112 ± 10 Specific tumor uptake of MabCAIXIRDye800CW was confirmed by a biodistribution assay and immunofluorescence imaging on tumor sections showed specific uptake in hypoxic tumor regions with higher contrast than conventional chromagenbased immunohistochemistry Molecular fluorescence imaging with MabCAIXIRDye800CW can be successfully used to detect hypoxic DCIS before and during surgery to facilitate radical resection Furthermore it allows for sensitive CAIXspecific immunofluorescence microscopy of tumor sections thereby introducing the concept of molecular fluorescence pathologyWe would like to thank A Martens for the pLVCMVLUC2IRESGFP vector and PC Pearlman for writing the algorithm in Matlab We are indebted to PWB Derksen and SG Elias for their suggestions concerning the mouse model Also we would like to thank the animal facility of the University Utrecht and the biobank of the University Medical Center Utrecht for their support This research was supported by the Center for Translational Molecular Medicine—Mammary Carcinoma Molecular Imaging for Diagnosis and Therapeutics CTMM—MAMMOTH Project 203—and by an unrestricted educational grant from Aegon to PJvD

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