title: Noninvasive brain cancer imaging with a bispecific antibody fragment, generated via click chemistry.
abstract: Early diagnosis remains a task of upmost importance for reducing cancer morbidity and mortality. Successful development of highly specific companion diagnostics targeting aberrant molecular pathways of cancer is needed for sensitive detection, accurate diagnosis, and opportune therapeutic intervention. Herein, we generated a bispecific immunoconjugate [denoted as Bs-F(ab)2] by linking two antibody Fab fragments, an anti-epidermal growth factor receptor (EGFR) Fab and an anti-CD105 Fab, via bioorthogonal "click" ligation of trans-cyclooctene and tetrazine. PET imaging of mice bearing U87MG (EGFR/CD105(+/+)) tumors with (64)Cu-labeled Bs-F(ab)2 revealed a significantly enhanced tumor uptake [42.9 ± 9.5 percentage injected dose per gram (%ID/g); n = 4] and tumor-to-background ratio (tumor/muscle ratio of 120.2 ± 44.4 at 36 h postinjection; n = 4) compared with each monospecific Fab tracer. Thus, we demonstrated that dual targeting of EGFR and CD105 provides a synergistic improvement on both affinity and specificity of (64)Cu-NOTA-Bs-F(ab)2. (64)Cu-NOTA-Bs-F(ab)2 was able to visualize small U87MG tumor nodules (<5 mm in diameter), owing to high tumor uptake (31.4 ± 10.8%ID/g at 36 h postinjection) and a tumor/muscle ratio of 76.4 ± 52.3, which provided excellent sensitivity for early detection. Finally, we successfully confirmed the feasibility of a ZW800-1-labeled Bs-F(ab)2 for near-infrared fluorescence imaging and image-guided surgical resection of U87MG tumors. More importantly, our rationale can be used in the construction of other disease-targeting bispecific antibody fragments for early detection and diagnosis of small malignant lesions.
authors.affiliation: Department of Radiology, University of Wisconsin-Madison, Madison, WI 53705;
authors.forename: Haiming
authors.initials: H
authors.lastname: Luo
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705;
authors.forename: Reinier
authors.initials: R
authors.lastname: Hernandez
authors.affiliation: Department of Radiology, University of Wisconsin-Madison, Madison, WI 53705;
authors.forename: Hao
authors.initials: H
authors.lastname: Hong
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705;
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Graves
authors.affiliation: Department of Radiology, University of Wisconsin-Madison, Madison, WI 53705;
authors.forename: Yunan
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705;
authors.forename: Christopher G
authors.initials: CG
authors.lastname: England
authors.affiliation: TRACON Pharmaceuticals, Inc., San Diego, CA 92122;
authors.forename: Charles P
authors.initials: CP
authors.lastname: Theuer
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705;
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Nickles
authors.affiliation: Department of Radiology, University of Wisconsin-Madison, Madison, WI 53705; Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705; Materials Science Program, University of Wisconsin-Madison, Madison, WI 53705; University of Wisconsin Carbone Cancer Center, Madison, WI 53705 wcai@uwhealth.org.
authors.forename: Weibo
authors.initials: W
authors.lastname: Cai
mesh_terms: D000818:Animals; D018033:Antibodies, Bispecific / Q000737:chemistry / Q000494:pharmacology*; D000912:Antibodies, Neoplasm / Q000737:chemistry / Q000494:pharmacology*; D001932:Brain Neoplasms / Q000000981:diagnostic imaging*; D057930:Click Chemistry; D003287:Contrast Media / Q000737:chemistry / Q000494:pharmacology*; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry / Q000494:pharmacology*; D051379:Mice; D009374:Neoplasms, Experimental / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography; D011859:Radiography
chemical_list: D018033:Antibodies, Bispecific; D000912:Antibodies, Neoplasm; D003287:Contrast Media; D007140:Immunoglobulin Fab Fragments
keywords: CD105; EGFR; bispecific antibody fragment; glioblastoma; positron emission tomography (PET)