Tumor targeting in vivo and metabolic fate of 5-[iodine-125]iodo-2'-deoxyuridine following intratumoral injection in patients with colorectal cancer.
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.
Mariani
G
G
CNR Institute of Clinical Physiology, University of Pisa, Italy.
Cei
A
A
Collecchi
P
P
Baranowska-Kortylewicz
J
J
Van den Abbeele
A D
AD
Di Luca
L
L
Di Stefano
R
R
Viacava
P
P
Ferdeghini
E M
EM
Di Sacco
S
S
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
D007457:Iodine Radioisotopes; D007065:Idoxuridine