Targeting the extradomain A of fibronectin allows identification of vascular resistance to antiangiogenic therapy in experimental glioma

// Guliz Acker 1, * , Sophie Kathe Piper 2, 3, * , Anna Lena Datwyler 2, 4 , Thomas Broggini 1 , Irina Kremenetskaia 1 , Melina Nieminen-Kelha 1 , Janet Lips 2, 4 , Ulrike Harms 2, 4 , Susanne Mueller 2, 4 , Gilla Lattig-Tunnemann 2, 4 , Eveline Trachsel 5 , Alessandro Palumbo 5 , Dario Neri 5 , Jan Klohs 4, 6 , Matthias Endres 2, 4 , Peter Vajkoczy 1, 2 , Christoph Harms 2, 4, * and Marcus Czabanka 1, * 1 Charite-Universitatsmedizin Berlin, Corporate Member of Freie Universitat Berlin, Humboldt-Universitat zu Berlin, and Berlin Institute of Health, Department of Neurosurgery, Berlin, Germany 2 Charite-Universitatsmedizin Berlin, Corporate Member of Freie Universitat Berlin, Humboldt-Universitat zu Berlin, and Berlin Institute of Health, Center for Stroke Research, Berlin, Germany 3 Charite-Universitatsmedizin Berlin, Corporate Member of Freie Universitat Berlin, Humboldt-Universitat zu Berlin, and Berlin Institute of Health, Institute of Biometry and Clinical Epidemiology, Berlin, Germany 4 Charite-Universitatsmedizin Berlin, Corporate Member of Freie Universitat Berlin, Humboldt-Universitat zu Berlin, and Berlin Institute of Health, Department of Neurology and Experimental Neurology, Berlin, Germany 5 Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland 6 Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland * These authors contributed equally to this work Correspondence to: Marcus Czabanka, email: marcus.czabanka@charite.de Christoph Harms, email: christoph.harms@charite.de Keywords: NIRF imaging; antiangiogenic resistance; F8; glioma; SF126 Received: March 15, 2018      Accepted: May 19, 2018      Published: June 12, 2018 ABSTRACT Introduction: Clinical application of antiangiogenic therapy lacks direct visualization of therapy efficacy and vascular resistance. We aimed to establish molecular imaging during treatment with sunitinib using the fibronectin extradomain A specific small immunoprotein(SIP)-F8 in glioma. Methods: Biodistribution analysis of F8-SIP-Alexa-555 was performed in SF126-glioma bearing or control mice ( n = 23 and 7, respectively). Intravital microscopy(IVM) was performed on a microvascular level after 7 days ( n = 5 per group) and subsequently after 6 days of sunitinib treatment ( n = 4) or without ( n = 2). Additionally, near infrared fluorescence(NIRF) imaging was established with F8-SIP-Alexa-750 allowing non-invasive imaging with and without antiangiogenic treatment in orthotopic tumors ( n = 38 divided in 4 groups). MRI was used to determine tumor size and served as a reference for NIRF imaging. Results: F8-SIP demonstrated a time and hemodynamic dependent tumor specific accumulation. A significantly higher vascular accumulation occurred with antiangiogenic treatment compared to untreated tumors enabling visualization of resistant tumor vessels by F8-SIP-mediated NIRF imaging. In orthotopic tumors, sunitinib reduced F8-SIP-Alexa-750 enrichment volume but not fluorescence intensity indicative of F8-SIP accumulation in fewer vessels. Conclusion: F8-SIP is highly tumor specific with time and hemodynamic dependent biodistribution. The higher vascular accumulation to remaining vessels enables molecular imaging and targeting of therapy resistant tumor vessels.