Near infrared fluorescence imaging of EGFR expressionin vivousing IRDye800CW-nimotuzumab

// Wendy Bernhard 1 , * , Ayman El-Sayed 1 , * , Kris Barreto 1 , Carolina Gonzalez 1 , Wayne Hill 1 , Angel Casaco Parada 2 , Humphrey Fonge 3 , 4 , 5 and C. Ronald Geyer 1 1 Department of Pathology, University of Saskatchewan, Saskatoon, Canada 2 Center for Molecular Immunology, Havana, Cuba 3 Department of Medical Imaging, University of Saskatchewan, Saskatoon, Canada 4 Department of Medical Imaging, Royal University Hospital, Saskatoon, Canada 5 Saskatchewan Centre for Cyclotron Sciences (SCCS), Fedoruk Centre, Saskatoon, Canada * These authors contributed equally to this work Correspondence to: C. Ronald Geyer, email: ron.geyer@usask.ca Humphrey Fonge, email: humphrey.fonge@usask.ca Keywords: nimotuzumab; near infrared fluorescence imaging; image-guided surgery; epidermal growth factor receptor; IRDye800CW Received: August 25, 2017      Accepted: October 27, 2017      Published: December 21, 2017 ABSTRACT Nimotuzumab is a humanized anti-epidermal growth factor receptor (EGFR) monoclonal antibody that is approved in many countries for the treatment of EGFR-positive cancers. Near infrared (NIR) fluorescent dye-labeled antibodies represent an attractive class of image-guided surgical probes because of their high specificity, tumor uptake, and low dissociation from tumor cells that express the antigen. In this study, we developed a NIR fluorescent dye-labeled nimotuzumab immunoconjugate, IRDye800CW-nimotuzumab, and evaluated in vitro binding with EGFR-positive cells, in vivo tumor uptake by NIR fluorescent imaging, and ex vivo biodistribution. There was no difference in binding between nimotuzumab and IRDye800CW-nimotuzumab to EGFR-positive cells. In mice bearing EGFR-positive xenografts, IRDye800CW-nimotuzumab uptake peaked at 4 days post injection and slowly decreased thereafter with high levels of accumulation still observed at 28 days post injection. In EGFR-positive xenografts, IRDye800CW-nimotuzumab showed more than 2-fold higher uptake in tumors compared to IRDye800CW-cetuximab. In addition, liver uptake of IRDye800CW-nimotuzumab was two-fold lower than cetuximab. The lower liver uptake of IRDye800CW-nimotuzumab could have implications on the selected dose for clinical trials of the immunoconjugate. In summary, this study shows that nimotuzumab is a good candidate for NIR fluorescent imaging and image-guided surgery.