Tetraspanin 8 (TSPAN 8) as a potential target for radio-immunotherapy of colorectal cancer

Abstract

// Aurelie Maisonial-Besset 1, 2, *, ** , Tiffany Witkowski 1, 2, *, ** , Isabelle Navarro-Teulon 3, 4, 5 , Odile Berthier-Vergnes 6, 7 , Giovanna Fois 2, 8 , Yingying Zhu 9, 10, 11 , Sophie Besse 1, 2 , Olivia Bawa 12 , Arnaud Briat 1, 2 , Mercedes Quintana 1, 2 , Alexandre Pichard 3, 4, 5 , Mathilde Bonnet 2, 13 , Eric Rubinstein 9, 10, 11 , Jean-Pierre Pouget 3, 4, 5 , Paule Opolon 12 , Lydia Maigne 2, 8 , Elisabeth Miot-Noirault 1, 2 , Jean-Michel Chezal 1, 2 , Claude Boucheix 9, 10, 11, * , Françoise Degoul 1, 2, * 1 INSERM, U 1240, Clermont-Ferrand, France 2 Université Clermont Auvergne, Imagerie Moléculaire et Thérapie Vectorisée, Clermont-Ferrand, France 3 IRCM, Institut de Recherche en Cancérologie de Montpellier, Montpellier, France 4 INSERM, U896, Montpellier, France 5 Université Montpellier 1, Montpellier, France 6 Université de Lyon 1, Lyon, France 7 CNRS, UMR5534, Centre de Génétique et de Physiologie Moléculaires et Cellulaires, Villeurbanne, France 8 CNRS/IN2P3, UMR6533, Laboratoire de Physique Corpusculaire (LPC), Clermont-Ferrand, France 9 INSERM, UMR-S 935, Villejuif, France 10 Université Paris-Sud 11, Orsay, France 11 Université Paris Saclay, Saint-Aubin, France 12 Gustave Roussy, Laboratoire de Pathologie Expérimentale, Villejuif, France 13 INSERM U1071, Faculté de Médecine, Clermont Ferrand, France * These authors have contributed equally to this work ** First co-authors Correspondence to: Françoise Degoul, email: francoise.degoul@inserm.fr Keywords: TSPAN8, radioimmunotherapy, colorectal cancer, dosimetry Abbreviations: DOTA: 2,2’,2’’-(10-(2-((2,5-dioxopyrrolidin-1-yl)oxy)-2-oxoethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid Received: December 12, 2016     Accepted: January 24, 2017     Published: February 28, 2017 ABSTRACT Tetraspanin 8 (TSPAN8) overexpression is correlated with poor prognosis in human colorectal cancer (CRC). A murine mAb Ts29.2 specific for human TSPAN8 provided significant efficiency for immunotherapy in CRC pre-clinical models. We therefore evaluate the feasability of targeting TSPAN8 in CRC with radiolabeled Ts29.2. Staining of tissue micro-arrays with Ts29.2 revealed that TSPAN8 espression was restricted to a few human healthy tissues. DOTA-Ts29.2 was radiolabeled with 111 In or 177 Lu with radiochemical purities >95%, specific activity ranging from 300 to 600 MBq/mg, and radioimmunoreactive fractions >80%. The biodistribution of [ 111 In]DOTA-Ts29.2 in nude mice bearing HT29 or SW480 CRC xenografts showed a high specificity of tumor localization with high tumor/blood ratios (HT29: 4.3; SW480-TSPAN8: 3.9 at 72h and 120h post injection respectively). Tumor-specific absorbed dose calculations for [ 177 Lu]DOTA-Ts29.2 was 1.89 Gy/MBq, establishing the feasibility of using radioimmunotherapy of CRC with this radiolabeled antibody. A significant inhibition of tumor growth in HT29 tumor-bearing mice treated with [ 177 Lu]DOTA-Ts29.2 was observed compared to control groups. Ex vivo experiments revealed specific DNA double strand breaks associated with cell apoptosis in [ 177 Lu]DOTA-Ts29.2 treated tumors compared to controls. Overall, we provide a proof-of-concept for the use of [ 111 In/ 177 Lu]DOTA-Ts29.2 that specifically target in vivo aggressive TSPAN8-positive cells in CRC.