title: Pretargeted PET Imaging Using a Site-Specifically Labeled Immunoconjugate.
abstract: In recent years, both site-specific bioconjugation techniques and bioorthogonal pretargeting strategies have emerged as exciting technologies with the potential to improve the safety and efficacy of antibody-based nuclear imaging. In the work at hand, we have combined these two approaches to create a pretargeted PET imaging strategy based on the rapid and bioorthogonal inverse electron demand Diels-Alder reaction between a (64)Cu-labeled tetrazine radioligand ((64)Cu-Tz-SarAr) and a site-specifically modified huA33-trans-cyclooctene immunoconjugate ((ss)huA33-PEG12-TCO). A bioconjugation strategy that harnesses enzymatic transformations and strain-promoted azide-alkyne click chemistry was used to site-specifically append PEGylated TCO moieties to the heavy chain glycans of the colorectal cancer-targeting huA33 antibody. Preclinical in vivo validation studies were performed in athymic nude mice bearing A33 antigen-expressing SW1222 human colorectal carcinoma xenografts. To this end, mice were administered (ss)huA33-PEG12-TCO via tail vein injection and-following accumulation intervals of 24 or 48 h-(64)Cu-Tz-SarAr. PET imaging and biodistribution studies reveal that this strategy clearly delineates tumor tissue as early as 1 h post-injection (6.7 ± 1.7%ID/g at 1 h p.i.), producing images with excellent contrast and high tumor-to-background activity concentration ratios (tumor:muscle = 21.5 ± 5.6 at 24 h p.i.). Furthermore, dosimetric calculations illustrate that this pretargeting approach produces only a fraction of the overall effective dose (0.0214 mSv/MBq; 0.079 rem/mCi) of directly labeled radioimmunoconjugates. Ultimately, this method effectively facilitates the high contrast pretargeted PET imaging of colorectal carcinoma using a site-specifically modified immunoconjugate.
authors.affiliation: Department of Chemistry, Hunter College of the City University of New York , 413 East 69th Street, New York, New York 10028, United States.|Ph.D. Program in Chemistry, The Graduate Center of the City University of New York , 365 Fifth Avenue, New York, New York 10016, United States.
authors.forename: Brendon E
authors.initials: BE
authors.lastname: Cook
authors.affiliation: Department of Chemistry, Hunter College of the City University of New York , 413 East 69th Street, New York, New York 10028, United States.
authors.forename: Pierre
authors.initials: P
authors.lastname: Adumeau
authors.affiliation: Department of Chemistry, Hunter College of the City University of New York , 413 East 69th Street, New York, New York 10028, United States.|Ph.D. Program in Chemistry, The Graduate Center of the City University of New York , 365 Fifth Avenue, New York, New York 10016, United States.
authors.forename: Rosemery
authors.initials: R
authors.lastname: Membreno
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Carnazza
authors.forename: Christian
authors.initials: C
authors.lastname: Brand
authors.affiliation: Department of Radiology, Weill Cornell Medical College , 520 East 70th Street, New York, New York 10065, United States.
authors.forename: Thomas
authors.initials: T
authors.lastname: Reiner
authors.affiliation: Licensing and Commercial Supply, Thermo Fisher Scientific , 29851 Willow Creek Road, Eugene, Oregon 97402, United States.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Agnew
authors.affiliation: Department of Radiology, Weill Cornell Medical College , 520 East 70th Street, New York, New York 10065, United States.
authors.forename: Jason S
authors.initials: JS
authors.lastname: Lewis
authors.affiliation: Department of Chemistry, Hunter College of the City University of New York , 413 East 69th Street, New York, New York 10028, United States.|Ph.D. Program in Chemistry, The Graduate Center of the City University of New York , 365 Fifth Avenue, New York, New York 10016, United States.|Department of Radiology, Weill Cornell Medical College , 520 East 70th Street, New York, New York 10065, United States.
authors.forename: Brian M
authors.initials: BM
authors.lastname: Zeglis
mesh_terms: D000480:Alkynes / Q000737:chemistry; D000818:Animals; D001386:Azides / Q000737:chemistry; D001665:Binding Sites; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology; D003301:Copper Radioisotopes; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry* / Q000378:metabolism / Q000493:pharmacokinetics; D007553:Isotope Labeling; D051379:Mice; D049268:Positron-Emission Tomography / Q000379:methods*; D014018:Tissue Distribution
chemical_list: D000480:Alkynes; D001386:Azides; D003301:Copper Radioisotopes; D018796:Immunoconjugates