title: ImmunoPET using engineered antibody fragments: fluorine-18 labeled diabodies for same-day imaging.
abstract: Combining the specificity of tumor-targeting antibodies with the sensitivity and quantification offered by positron emission tomography (PET) provides tremendous opportunities for molecular characterization of tumors in vivo. Until recently, significant challenges have been faced when attempting to combine antibodies which show long biological half-lives and positron-emitting radionuclides with comparably short physical half-lives, in particular (18)F (half-life, 109 min). A fast and simple microwave-assisted method of generating N-succinimidyl-4-[(18)F]fluorobenzoate has been developed and employed for radiolabeling a small, rapidly targeting HER2-specific engineered antibody fragment, the cys-diabody. Using this tracer, HER2-positive tumor xenografts in mice were detected at 1-4 h post-injection by microPET. This confirms the rapid kinetics of [(18)F]fluorobenzoyl cys-diabody localization, and demonstrates the feasibility of same-day immunoPET imaging. This approach can be broadly applied to antibodies targeting cell surface biomarkers for molecular imaging of tumors and should be highly translatable for clinical use.
authors.affiliation: Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, 570 Westwood Plaza, CNSI 4335, Box 951770, Los Angeles, CA 90095-1770, USA.
authors.forename: Tove
authors.initials: T
authors.lastname: Olafsen
authors.forename: Shannon J
authors.initials: SJ
authors.lastname: Sirk
authors.forename: Sebastian
authors.initials: S
authors.lastname: Olma
authors.forename: Clifton K-F
authors.initials: CK
authors.lastname: Shen
authors.forename: Anna M
authors.initials: AM
authors.lastname: Wu
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000000981:diagnostic imaging; D045744:Cell Line, Tumor; D005260:Female; D005462:Fluorine Radioisotopes / Q000737:chemistry; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry / Q000276:immunology; D051379:Mice; D008819:Mice, Nude; D057054:Molecular Imaging; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology; D057127:Single-Chain Antibodies / Q000737:chemistry / Q000276:immunology; D014057:Tomography, X-Ray Computed; D014183:Transplantation, Heterologous
chemical_list: D005462:Fluorine Radioisotopes; D018796:Immunoconjugates; D018719:Erb-b2 Receptor Tyrosine Kinases; D057127:Single-Chain Antibodies