BACKGROUND: Intact antibodies are poor imaging agents due to a long serum half-life (10-20 d) preventing adequate contrast between the tumor and surrounding blood. Smaller engineered antibody fragments overcome this problem by exhibiting shorter serum half-lives (4-20 h).The diabody (55 kDa) is the smallest antibody fragment, which retains the bivalency of the intact antibody. Our goal was to develop and characterize the anti-CA19-9 diabody fragment and determine its ability to provide antigen specific imaging of pancreas cancer. METHODS: The diabody DNA construct was created by isolation of the variable region genes of the intact anti-CA19-9 antibody. Diabody expression was carried out in NS0 cells and purified using HPLC from supernatant. Specific antigen binding was confirmed with flow cytometry and immunofluorescence. Radiolabeled diabody was injected into mice harboring an antigen positive xenograft (BxPC3 or Capan-2) and a negative xenograft (MiaPaca-2). MicroCT and MicroPET were performed at successive time intervals after injection. Radioactivity was measured in blood and tumor to provide objective confirmation of the microPET images. RESULTS: Immunofluorescence and flow cytometry showed specific binding of the anti-CA19-9 diabody. Pancreas xenograft imaging of BxPC3/MiaPaca-2 and Capan-2/MiaPaca-2 models with the anti-CA19-9 diabody demonstrated an average tumor:blood ratio of 5.0 and 2.0, respectively, and an average positive:negative tumor ratio of 11 and 6, respectively. With respect to the tumor:blood ratio, these data indicate five times and two times more radioactivity in the tumor than in the blood yielding adequate contrast between tumor tissue and background (i.e., blood) to create the representative microPET images. CONCLUSIONS: We successfully engineered a functional diabody against CA19-9, a tumor antigen present on the vast majority of pancreas cancers. Additionally, we demonstrate high contrast antigen specific microPET imaging of pancreas cancer in xenograft models. Published by Elsevier Inc.
BACKGROUND: Intact antibodies are poor imaging agents due to a long serum half-life (10-20 d) preventing adequate contrast between the tumor and surrounding blood. Smaller engineered antibody fragments overcome this problem by exhibiting shorter serum half-lives (4-20 h).The diabody (55 kDa) is the smallest antibody fragment, which retains the bivalency of the intact antibody. Our goal was to develop and characterize the anti-CA19-9 diabody fragment and determine its ability to provide antigen specific imaging of pancreas cancer. METHODS: The diabody DNA construct was created by isolation of the variable region genes of the intact anti-CA19-9 antibody. Diabody expression was carried out in NS0 cells and purified using HPLC from supernatant. Specific antigen binding was confirmed with flow cytometry and immunofluorescence. Radiolabeled diabody was injected into mice harboring an antigen positive xenograft (BxPC3 or Capan-2) and a negative xenograft (MiaPaca-2). MicroCT and MicroPET were performed at successive time intervals after injection. Radioactivity was measured in blood and tumor to provide objective confirmation of the microPET images. RESULTS: Immunofluorescence and flow cytometry showed specific binding of the anti-CA19-9 diabody. Pancreas xenograft imaging of BxPC3/MiaPaca-2 and Capan-2/MiaPaca-2 models with the anti-CA19-9 diabody demonstrated an average tumor:blood ratio of 5.0 and 2.0, respectively, and an average positive:negative tumor ratio of 11 and 6, respectively. With respect to the tumor:blood ratio, these data indicate five times and two times more radioactivity in the tumor than in the blood yielding adequate contrast between tumor tissue and background (i.e., blood) to create the representative microPET images. CONCLUSIONS: We successfully engineered a functional diabody against CA19-9, a tumor antigen present on the vast majority of pancreas cancers. Additionally, we demonstrate high contrast antigen specific microPET imaging of pancreas cancer in xenograft models. Published by Elsevier Inc.
Authors: Nerissa Therese Viola-Villegas; Samuel L Rice; Sean Carlin; Xiaohong Wu; Michael J Evans; Kuntal K Sevak; Marija Drobjnak; Govind Ragupathi; Ritsuko Sawada; Wolfgang W Scholz; Philip O Livingston; Jason S Lewis Journal: J Nucl Med Date: 2013-09-12 Impact factor: 10.057
Authors: Keyu Li; Kirstin A Zettlitz; Julia Lipianskaya; Yu Zhou; James D Marks; Parag Mallick; Robert E Reiter; Anna M Wu Journal: Protein Eng Des Sel Date: 2015-05-19 Impact factor: 1.650
Authors: Jacob L Houghton; Rosemery Membreno; Dalya Abdel-Atti; Kristen M Cunanan; Sean Carlin; Wolfgang W Scholz; Pat B Zanzonico; Jason S Lewis; Brian M Zeglis Journal: Mol Cancer Ther Date: 2016-11-09 Impact factor: 6.261
Authors: Jacob L Houghton; Brian M Zeglis; Dalya Abdel-Atti; Ritsuko Sawada; Wolfgang W Scholz; Jason S Lewis Journal: J Nucl Med Date: 2015-10-15 Impact factor: 10.057
Authors: Jason S Lewis; Wolfgang A Weber; Christian Lohrmann; Eileen M O'Reilly; Joseph A O'Donoghue; Neeta Pandit-Taskar; Jorge A Carrasquillo; Serge K Lyashchenko; Shutian Ruan; Rebecca Teng; Wolfgang Scholz; Paul W Maffuid Journal: Clin Cancer Res Date: 2019-09-20 Impact factor: 12.531