title: Tumor targeting in vivo and metabolic fate of 5-[iodine-125]iodo-2'-deoxyuridine following intratumoral injection in patients with colorectal cancer.
abstract: Previous studies have demonstrated the tumor-targeting potential of radioiodinated 5-iodo-2'-deoxyuridine (IUdR) in experimental animal models following direct intratumoral or intracavitary administration. The aim of this study was to measure the tumor uptake and metabolic fate of 5-[125I]iodo-2'-deoxyuridine ([125I]UdR) in humans after a single intratumoral injection. Ten patients with colorectal cancer were injected intratumorally with [125I]UdR) (0.24-3.9 MBq) during endoscopy 24 hr before ablative surgery. Blood and urine samples were collected up to 72 hr after [125I]UdR injection. Following resection, the radioactivity in the tumor and the surrounding tissues was measured in a gamma counter, and microautoradiography was performed on semi-thin tissue sections to assess localization of the radiopharmaceutical at the cellular level. An average of 0.234% of the injected dose was present per gram of tumor (range 0.009-0.918, median value 0.147), and tumor-to-nontumor radioactivity incorporation ratios were high for colonic mucosa when the nontumor tissue was taken at 1 cm (mean 629, range 27-2391) and 15 cm (mean 2387, range 122-12674) from the injection site. Microautoradiography confirmed these high tumor-to-nontumor ratios and demonstrated localization of [125I]UdR in the tumor cell nuclei. These results suggest that radioiodinated IUdR might have potential as a tumor-targeting agent in humans, provided homogeneous intratumoral distribution of the radiopharmaceutical by a suitable route of loco-regional administration can be achieved.
authors.affiliation: CNR Institute of Clinical Physiology, University of Pisa, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Mariani
authors.forename: A
authors.initials: A
authors.lastname: Cei
authors.forename: P
authors.initials: P
authors.lastname: Collecchi
authors.forename: J
authors.initials: J
authors.lastname: Baranowska-Kortylewicz
authors.forename: A D
authors.initials: AD
authors.lastname: Van den Abbeele
authors.forename: L
authors.initials: L
authors.lastname: Di Luca
authors.forename: R
authors.initials: R
authors.lastname: Di Stefano
authors.forename: P
authors.initials: P
authors.lastname: Viacava
authors.forename: E M
authors.initials: EM
authors.lastname: Ferdeghini
authors.forename: S
authors.initials: S
authors.lastname: Di Sacco
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging*; D000368:Aged; D000369:Aged, 80 and over; D001345:Autoradiography; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007065:Idoxuridine; D007091:Image Processing, Computer-Assisted; D015552:Injections, Intralesional; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D016719:Radioimmunodetection
chemical_list: D007457:Iodine Radioisotopes; D007065:Idoxuridine