title: Preclinical uPAR-targeted multimodal imaging of locoregional oral cancer.
abstract: Establishing adequate resection margins and lymphatic mapping are crucial for the prognosis of oral cancer patients. Novel targeted imaging modalities are needed, enabling pre- and intraoperative detection of tumour cells, in combination with improved post-surgical examination by the pathologist. The urokinase-receptor (uPAR) is overexpressed in head and neck cancer, where it is associated with tumour progression and metastasis.
  
  
  
  To determine suitability of uPAR for molecular imaging of oral cancer surgery, human head and neck tumours were sectioned and stained for uPAR to evaluate the expression pattern compared to normal mucosa. Furthermore, metastatic oral squamous carcinoma cell line OSC-19 was used for targeting uPAR in in vivo mouse models. Using anti-uPAR antibody ATN-658, equipped with a multimodal label, the in vivo specificity was investigated and the optimal dose and time-window were evaluated.
  
  
  
  All human oral cancer tissues expressed uPAR in epithelial and stromal cells. Hybrid ATN-658 clearly visualized tongue tumours in mice using either NIRF or SPECT imaging. Mean fluorescent TBRs over time were 4.3±0.7 with the specific tracer versus 1.7±0.1 with a control antibody. A significant difference in TBRs could be seen between 1nmol (150μg) and 0.34nmol (50μg) dose groups (n=4, p<0.05). Co-expression between BLI, GFP and the NIR fluorescent signals were seen in the tongue tumour, whereas human cytokeratin staining confirmed presence of malignant cells in the positive cervical lymph nodes.
  
  
  
  This study shows the applicability of an uPAR specific multimodal tracer in an oral cancer model, combining SPECT with intraoperative guidance.
authors.affiliation: Department of Surgery, Leiden University Medical Centre, Leiden, Netherlands.
authors.forename: M C
authors.initials: MC
authors.lastname: Boonstra
authors.affiliation: Department of Radiology, Erasmus Medical Centre, Rotterdam, Netherlands.
authors.forename: P B A A
authors.initials: PBAA
authors.lastname: Van Driel
authors.affiliation: Department of Otorhinolaryngology, and Head & Neck Surgery, Erasmus Medical Centre, Rotterdam, Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Keereweer
authors.affiliation: Department of Surgery, Leiden University Medical Centre, Leiden, Netherlands.
authors.forename: H A J M
authors.initials: HAJM
authors.lastname: Prevoo
authors.affiliation: Department of Radiology, Leiden University Medical Centre, Leiden, Netherlands; Percuros BV, Enschede, Netherlands.
authors.forename: M A
authors.initials: MA
authors.lastname: Stammes
authors.affiliation: Department of Surgery, Leiden University Medical Centre, Leiden, Netherlands.
authors.forename: V M
authors.initials: VM
authors.lastname: Baart
authors.affiliation: Department of Radiology, Erasmus Medical Centre, Rotterdam, Netherlands.
authors.forename: C W G M
authors.initials: CWGM
authors.lastname: Löwik
authors.affiliation: Monopar Therapeutics Inc, Northbrook, IL, United States.
authors.forename: A P
authors.initials: AP
authors.lastname: Mazar
authors.affiliation: Department of Surgery, Leiden University Medical Centre, Leiden, Netherlands.
authors.forename: C J H
authors.initials: CJH
authors.lastname: van de Velde
authors.affiliation: Department of Surgery, Leiden University Medical Centre, Leiden, Netherlands.
authors.forename: A L
authors.initials: AL
authors.lastname: Vahrmeijer
authors.affiliation: Department of Surgery, Leiden University Medical Centre, Leiden, Netherlands; Antibodies for Research Applications BV, Gouda, Netherlands. Electronic address: c.f.m.sier@lumc.nl.
authors.forename: C F M
authors.initials: CFM
authors.lastname: Sier
mesh_terms: D000818:Animals; D005260:Female; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009062:Mouth Neoplasms / Q000000981:diagnostic imaging* / Q000201:enzymology; D064847:Multimodal Imaging; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*
chemical_list: D014568:Urokinase-Type Plasminogen Activator
keywords: Fluorescence; Head and neck; Hybrid; Imaging; Intraoperative; Near-infrared; Oral cancer; Real-time; SPECT; Surgery