title: ¹¹¹In-DOTA-Annexin V for imaging of apoptosis during HSV1-tk/GCV prodrug activation gene therapy in mice with NG4TL4 sarcoma.
abstract: BACKGROUND
  Apoptosis has been suggested as a cytocidal mechanism of the HSV1-tk-expressing cells when exposed to ganciclovir (GCV). This study evaluated the efficacy of (111)In-labeled Annexin V for monitoring tumor responses during prodrug activation gene therapy with HSV1-tk and GCV.
  
  
  METHODS
  Annexin V was conjugated to DOTA using N-hydroxysulfosuccinimide (sulfo-NHS) and 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC), labeled with (111)In-InCl3 and purified using size exclusion chromatography to give (111)In-DOTA-Annexin V conjugate. The radiochemical yield and the radiochemical purity of (111)In-DOTA-Annexin V were 74±12% and 98±3%, respectively (n=10). (111)In-DOTA-BSA was prepared similarly. An in vitro study to demonstrate the apoptosis of NG4TL4-STK cells after GCV treatment has been performed. Mice bearing NG4TL4-STK and NG4TL4-WT tumors were treated with GCV (10 mg/kg daily) by i.p. injection for 7 consecutive days. Before and during the GCV treatment, biodistribution studies and scintigraphic imaging were performed at 2h post injection of the radiotracers.
  
  
  RESULTS
  The uptake of (111)In-DOTA-Annexin V in treated cells (13.41±1.30%) was 4.1 times higher than that in untreated cells (3.21±0.37%). The GCV-induced cell apoptosis in NG4TL4-STK tumor resulted in a significantly increasing accumulation of (111)In-DOTA-Annexin V (1.92±0.32%ID/g at day 0, 4.79±0.86%ID/g at day 2, 4.56±0.58%ID/g at day 4) was observed, but not for that of (111)In-DOTA-BSA. During consecutive GCV treatment, scintigraphic imaging with (111)In-DOTA-Annexin V revealed high uptake in NG4TL4-STK tumor compared with that in NG4TL4-WT tumor. However, no specific (111)In-DOTA-BSA accumulation in NG4TL4-STK and NG4TL4-WT tumors was observed throughout the course of GCV treatment.
  
  
  CONCLUSIONS
  This study demonstrated that (111)In-DOTA-Annexin V can be used for monitoring tumor cell apoptosis during prodrug activation gene therapy with HSV1-tk and GCV for cancer treatment.
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No. 155 Li-Nong Street, Section 2, Pei-Tou, Taipei 11221, Taiwan; Division of Nuclear Medicine, Taipei City Hospital Zhongxiao Branch, No.145, Zhengzhou Rd., Datong Dist., Taipei City 10341, Taiwan; Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, No. 155 Li-Nong Street, Section 2, Pei-Tou, Taipei 11221, Taiwan.
authors.forename: Ming-Hsien
authors.initials: MH
authors.lastname: Lin
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No. 155 Li-Nong Street, Section 2, Pei-Tou, Taipei 11221, Taiwan.
authors.forename: Shih-Yen
authors.initials: SY
authors.lastname: Wu
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No. 155 Li-Nong Street, Section 2, Pei-Tou, Taipei 11221, Taiwan.
authors.forename: Hsin-Ell
authors.initials: HE
authors.lastname: Wang
authors.affiliation: Department of Nuclear Medicine, Faculty of Medicine, National Yang-Ming University, No. 155 Li-Nong Street, Section 2, Pei-Tou, Taipei 11221, Taiwan. Electronic address: rsliu@vghtpe.gov.tw.
authors.forename: Ren-Shyan
authors.initials: RS
authors.lastname: Liu
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No. 155 Li-Nong Street, Section 2, Pei-Tou, Taipei 11221, Taiwan. Electronic address: jcchen@ym.edu.tw.
authors.forename: Jyh-Cheng
authors.initials: JC
authors.lastname: Chen
mesh_terms: D000818:Animals; D017304:Annexin A5 / Q000737:chemistry / Q000493:pharmacokinetics*; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D056831:Coordination Complexes / Q000737:chemistry / Q000493:pharmacokinetics*; D016903:Drug Monitoring / Q000379:methods; D015774:Ganciclovir / Q000008:administration & dosage; D015316:Genetic Therapy / Q000379:methods*; D018259:Herpesvirus 1, Human / Q000201:enzymology; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry / Q000493:pharmacokinetics*; D007553:Isotope Labeling / Q000379:methods; D008657:Metabolic Clearance Rate; D051379:Mice; D011355:Prodrugs / Q000008:administration & dosage*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000138:chemical synthesis / Q000493:pharmacokinetics; D012509:Sarcoma / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000628:therapy*; D013937:Thymidine Kinase / Q000235:genetics / Q000378:metabolism; D014018:Tissue Distribution; D016896:Treatment Outcome
chemical_list: D017304:Annexin A5; D056831:Coordination Complexes; D006573:Heterocyclic Compounds, 1-Ring; D011355:Prodrugs; D019275:Radiopharmaceuticals; C586738:indium-111-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid; D013937:Thymidine Kinase; D015774:Ganciclovir
keywords: Annexin V; Apoptosis; Cancer; Ganciclovir; Gene therapy