title: [131I]FIAU labeling of genetically transduced, tumor-reactive lymphocytes: cell-level dosimetry and dose-dependent toxicity.
abstract: OBJECTIVE
  Donor T cells have been shown to be reactive against and effective in adoptive immunotherapy of Epstein-Barr virus (EBV) lymphomas which develop in some leukemia patients post marrow transplantation. These T cells may be genetically modified by incorporation of a replication-incompetent viral vector (NIT) encoding both an inactive mutant nerve growth factor receptor (LNGFR), as an immunoselectable surface marker, and a herpes simplex virus thymidine kinase (HSV-TK), rendering the cells sensitive to ganciclovir. The current studies are based on the selective HSV-TK-catalyzed trapping (phosphorylation) of the thymidine analog [(131)I]-2'-fluoro-2'-deoxy-1-beta-D-arabinofuransyl-5-iodo-uracil (FIAU) as a means of stably labeling such T cells for in vivo trafficking (including tumor targeting) studies. Because of the radiosensitivity of lymphocytes and the potentially high absorbed dose to the nucleus from intracellular (131)I (even at tracer levels), the nucleus absorbed dose (D ( n )) and dose-dependent immune functionality were evaluated for NIT(+) T cells labeled ex vivo in [(131)I]FIAU-containing medium.
  
  
  METHODS
  Based on in vitro kinetic studies of [(131)I]FIAU uptake by NIT(+) T cells, D ( n ) was calculated using an adaptation of the MIRD formalism and the recently published MIRD cellular S factors. Immune cytotoxicity of [(131)I]FIAU-labeled cells was assayed against (51)Cr-labeled target cells [B-lymphoblastoid cells (BLCLs)] in a standard 4-h release assay.
  
  
  CONCLUSIONS
  At median nuclear absorbed doses up to 830 cGy, a (51)Cr-release assay against BLCLs showed no loss of immune cytotoxicity, thus demonstrating the functional integrity of genetically transduced, tumor-reactive T cells labeled at this dose level for in vivo cell trafficking and tumor targeting studies.
authors.affiliation: Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY, USA. zanzonip@MSKCC.ORG
authors.forename: Pat
authors.initials: P
authors.lastname: Zanzonico
authors.forename: Guenther
authors.initials: G
authors.lastname: Koehne
authors.forename: Humilidad F
authors.initials: HF
authors.lastname: Gallardo
authors.forename: Mikhail
authors.initials: M
authors.lastname: Doubrovin
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Doubrovina
authors.forename: Ronald
authors.initials: R
authors.lastname: Finn
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Blasberg
authors.forename: Isabelle
authors.initials: I
authors.lastname: Riviere
authors.forename: Richard J
authors.initials: RJ
authors.lastname: O'Reilly
authors.forename: Michel
authors.initials: M
authors.lastname: Sadelain
authors.forename: Steven M
authors.initials: SM
authors.lastname: Larson
mesh_terms: D000818:Animals; D001086:Arabinofuranosyluracil / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D003602:Cytotoxicity, Immunologic; D004307:Dose-Response Relationship, Radiation; D020031:Epstein-Barr Virus Infections / Q000000981:diagnostic imaging / Q000276:immunology / Q000628:therapy; D019337:Hematologic Neoplasms / Q000000981:diagnostic imaging / Q000276:immunology* / Q000628:therapy*; D006801:Humans; D016219:Immunotherapy, Adoptive; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D051379:Mice; D016513:Mice, SCID; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000528:radiation effects; D014161:Transduction, Genetic
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D001086:Arabinofuranosyluracil; C043457:fialuridine