title: Preliminary evaluation of serial (18) FDG-PET/CT to assess response to toceranib phosphate therapy in canine cancer.
abstract: Palladia(TM)  (toceranib phosphate-Pfizer Animal Health) is a novel orally administered receptor tyrosine kinase inhibitor (TKI) approved for treatment of canine mast cell tumors. Receptor tyrosine kinase dysregulation leads to tumor growth, progression, and metastasis. Toceranib's targets include vascular endothelial growth factor receptor (VEGFR-2/Flk-1/KDR), platelet-derived growth factor receptor, and kit. Positron Emission Tomography/Computed Tomography (PET/CT) is used commonly to diagnose, prognosticate, and monitor response to antineoplastic therapy in human patients. In this study, serial PET/CT imaging with (18) F-fluorodeoxyglucose ((18) FDG) was used to assess response to toceranib therapy in dogs with measurable solid malignancies. Six tumor-bearing dogs underwent tumor assessment using both standard RECIST criteria and PET/CT prior to and at a median of 5 weeks postinitiation of toceranib treatment. Toceranib was prescribed initially at a target dose 3.25 mg/kg PO q48 h, with subsequent modifications based on observed toxicity. Treatment was continued in patients achieving stable disease with acceptable drug tolerance. One dog was maintained on drug despite dose modification due to toxicity; measurable clinical and image-based responses were seen after 10 weeks of therapy. All others had stable or progressive disease based on clinical restaging and PET/CT at first recheck. . Due to discordance with anatomic and metabolic imaging, further studies are needed to investigate the role of molecular imaging in assessment of drug response and identify other potential molecular targets of toceranib.
authors.affiliation: Department of Small Animal Clinical Sciences, University of Tennessee College of Veterinary Medicine, Knoxville, TN 37996, USA. aleblanc@utk.edu
authors.forename: Amy K
authors.initials: AK
authors.lastname: Leblanc
authors.forename: Ashley N
authors.initials: AN
authors.lastname: Miller
authors.forename: Gina D
authors.initials: GD
authors.lastname: Galyon
authors.forename: Tamberlyn D
authors.initials: TD
authors.lastname: Moyers
authors.forename: Misty J
authors.initials: MJ
authors.lastname: Long
authors.forename: Alan C
authors.initials: AC
authors.lastname: Stuckey
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Wall
authors.forename: Federica
authors.initials: F
authors.lastname: Morandi
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D004283:Dog Diseases / Q000000981:diagnostic imaging* / Q000188:drug therapy; D004285:Dogs; D019788:Fluorodeoxyglucose F18; D007211:Indoles / Q000627:therapeutic use*; D064847:Multimodal Imaging / Q000662:veterinary*; D009369:Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000662:veterinary*; D049268:Positron-Emission Tomography; D011758:Pyrroles / Q000627:therapeutic use*; D019275:Radiopharmaceuticals; D020794:Receptor Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D014057:Tomography, X-Ray Computed
chemical_list: D000970:Antineoplastic Agents; D007211:Indoles; D011758:Pyrroles; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; C464577:toceranib phosphate; D020794:Receptor Protein-Tyrosine Kinases