title: Preclinical evaluation of a novel CEA-targeting near-infrared fluorescent tracer delineating colorectal and pancreatic tumors.
abstract: Surgery is the cornerstone of oncologic therapy with curative intent. However, identification of tumor cells in the resection margins is difficult, resulting in nonradical resections, increased cancer recurrence and subsequent decreased patient survival. Novel imaging techniques that aid in demarcating tumor margins during surgery are needed. Overexpression of carcinoembryonic antigen (CEA) is found in the majority of gastrointestinal carcinomas, including colorectal and pancreas. We developed ssSM3E/800CW, a novel CEA-targeted near-infrared fluorescent (NIRF) tracer, based on a disulfide-stabilized single-chain antibody fragment (ssScFv), to visualize colorectal and pancreatic tumors in a clinically translatable setting. The applicability of the tracer was tested for cell and tissue binding characteristics and dosing using immunohistochemistry, flow cytometry, cell-based plate assays and orthotopic colorectal (HT-29, well differentiated) and pancreatic (BXPC-3, poorly differentiated) xenogeneic human-mouse models. NIRF signals were visualized using the clinically compatible FLARE™ imaging system. Calculated clinically relevant doses of ssSM3E/800CW selectively accumulated in colorectal and pancreatic tumors/cells, with highest tumor-to-background ratios of 5.1 ± 0.6 at 72 hr postinjection, which proved suitable for intraoperative detection and delineation of tumor boarders and small (residual) tumor nodules in mice, between 8 and 96 hr postinjection. Ex vivo fluorescence imaging and pathologic examination confirmed tumor specificity and the distribution of the tracer. Our results indicate that ssSM3E/800CW shows promise as a diagnostic tool to recognize colorectal and pancreatic cancers for fluorescent-guided surgery applications. If successfully translated clinically, this tracer could help improve the completeness of surgery and thus survival.
authors.affiliation: Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Martin C
authors.initials: MC
authors.lastname: Boonstra
authors.affiliation: Department of Oncology, Royal Free & University College Medical School, London, United Kingdom.
authors.forename: Berend
authors.initials: B
authors.lastname: Tolner
authors.affiliation: Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Boudewijn E
authors.initials: BE
authors.lastname: Schaafsma
authors.affiliation: Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Leonora S F
authors.initials: LS
authors.lastname: Boogerd
authors.affiliation: Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Hendrica A J M
authors.initials: HA
authors.lastname: Prevoo
authors.affiliation: Department of Oncology, Royal Free & University College Medical School, London, United Kingdom.
authors.forename: Guarav
authors.initials: G
authors.lastname: Bhavsar
authors.affiliation: Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Peter J K
authors.initials: PJ
authors.lastname: Kuppen
authors.affiliation: Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Cornelis F M
authors.initials: CF
authors.lastname: Sier
authors.affiliation: Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Bert A
authors.initials: BA
authors.lastname: Bonsing
authors.affiliation: Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA.|Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA.|Curadel, LLC, Worcester, MA.
authors.forename: John V
authors.initials: JV
authors.lastname: Frangioni
authors.affiliation: Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Cornelis J H
authors.initials: CJ
authors.lastname: van de Velde
authors.affiliation: Department of Oncology, Royal Free & University College Medical School, London, United Kingdom.
authors.forename: Kerry A
authors.initials: KA
authors.lastname: Chester
authors.affiliation: Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Alexander L
authors.initials: AL
authors.lastname: Vahrmeijer
mesh_terms: D000818:Animals; D001557:Benzenesulfonates / Q000737:chemistry*; D018938:Caco-2 Cells; D002272:Carcinoembryonic Antigen / Q000378:metabolism*; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D004353:Drug Evaluation, Preclinical; D005260:Female; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D007211:Indoles / Q000737:chemistry*; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009928:Organ Specificity; D010190:Pancreatic Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D057127:Single-Chain Antibodies / Q000737:chemistry; D019265:Spectroscopy, Near-Infrared
chemical_list: D001557:Benzenesulfonates; D002272:Carcinoembryonic Antigen; C562366:IRDye 800CW; D007211:Indoles; D057127:Single-Chain Antibodies
keywords: CEACAM5; NIR fluorescence; clinical translation; image guided; surgery