title: Biodistribution and Targeting of Anti-5T4 Antibody-Drug Conjugate Using Fluorescence Molecular Tomography.
abstract: Understanding a drug's whole-body biodistribution and tumor targeting can provide important information regarding efficacy, safety, and dosing parameters. Current methods to evaluate biodistribution include in vivo imaging technologies like positron electron tomography and single-photon emission computed tomography or ex vivo quantitation of drug concentrations in tissues using autoradiography and standard biochemical assays. These methods use radioactive compounds or are cumbersome and do not give whole-body information. Here, for the first time, we show the utility of fluorescence molecular tomography (FMT) imaging to determine the biodistribution and targeting of an antibody-drug conjugate (ADC). An anti-5T4-antibody (5T4-Ab) and 5T4-ADC were conjugated with a near-infrared (NIR) fluorophore VivoTag 680XL (VT680). Both conjugated compounds were stable as determined by SEC-HPLC and plasma stability studies. Flow cytometry and fluorescence microscopy studies showed that VT680-conjugated 5T4-ADC specifically bound 5T4-expressing cells in vitro and also exhibited a similar cytotoxicity profile as the unconjugated 5T4-ADC. In vivo biodistribution and tumor targeting in an H1975 subcutaneous xenograft model demonstrated no significant differences between accumulation of VT680-conjugated 5T4-Ab or 5T4-ADC in either normal tissues or tumor. In addition, quantitation of heart signal from FMT imaging showed good correlation with the plasma pharmacokinetic profile suggesting that it (heart FMT imaging) may be a surrogate for plasma drug clearance. These results demonstrate that conjugation of VT680 to 5T4-Ab or 5T4-ADC does not change the behavior of native biologic, and FMT imaging can be a useful tool to understand biodistribution and tumor-targeting kinetics of antibodies, ADCs, and other biologics. Mol Cancer Ther; 15(10); 2530-40. ©2016 AACR.
authors.affiliation: Global Science & Technology - Comparative Medicine, Pfizer Inc., San Diego, California. anand.giddabasappa@pfizer.com.
authors.forename: Anand
authors.initials: A
authors.lastname: Giddabasappa
authors.affiliation: Global Science & Technology - Comparative Medicine, Pfizer Inc., San Diego, California.
authors.forename: Vijay R
authors.initials: VR
authors.lastname: Gupta
authors.affiliation: Global Science & Technology - Comparative Medicine, Pfizer Inc., San Diego, California.
authors.forename: Rand
authors.initials: R
authors.lastname: Norberg
authors.affiliation: Global Science & Technology - Comparative Medicine, Pfizer Inc., San Diego, California.
authors.forename: Parul
authors.initials: P
authors.lastname: Gupta
authors.affiliation: Pharmacokinetics Dynamics and Metabolism, Pfizer Inc., San Diego, California.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Spilker
authors.affiliation: Pharmacokinetics Dynamics and Metabolism, Pfizer Inc., Groton, Connecticut.
authors.forename: Joann
authors.initials: J
authors.lastname: Wentland
authors.affiliation: Pharmacokinetics Dynamics and Metabolism, Pfizer Inc., Groton, Connecticut.
authors.forename: Brian
authors.initials: B
authors.lastname: Rago
authors.affiliation: Global Science & Technology - Comparative Medicine, Pfizer Inc., San Diego, California.
authors.forename: Jeetendra
authors.initials: J
authors.lastname: Eswaraka
authors.affiliation: Pharmacokinetics Dynamics and Metabolism, Pfizer Inc., Pearl River, New York.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Leal
authors.affiliation: Oncology Research Unit, Pfizer Inc., Pearl River, New York.
authors.forename: Puja
authors.initials: P
authors.lastname: Sapra
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000493:pharmacokinetics*; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D005453:Fluorescence; D006801:Humans; D018796:Immunoconjugates / Q000493:pharmacokinetics*; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051379:Mice; D057054:Molecular Imaging; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000378:metabolism; D014018:Tissue Distribution; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D018796:Immunoconjugates; D008562:Membrane Glycoproteins; C063709:trophoblastic glycoprotein 5T4, human