Radiolabeled neurotensin analog, 99mTc-NT-XI, evaluated in ductal pancreatic adenocarcinoma patients.
The study aim was to assess the safety, biodistribution, tissue kinetics, and tumor uptake of the (99m)Tc-labeled neurotensin (NT) analog NT-XI.


METHODS
Four patients presenting ductal pancreatic adenocarcinoma were studied with (99m)Tc-NT-XI. Patients were followed by scintigraphy up to 4 h and by continued blood and urinary sampling until surgery 18-22 h after injection. Surgical tissue samples were analyzed for radioactivity uptake and NT receptor expression.


RESULTS
No side effects were observed on injection of (99m)Tc-NT-XI. Blood biologic half-lives alpha and beta were 35 min (range, 17-62 min) and 230 min (range, 107-383 min), respectively. Repeated whole-body scintigraphy performed in 2 patients showed a single exponential decrease of whole-body activity with half-lives of 101 and 232 min. Tracer elimination was mainly renal, with 92% and 98% of activity counted in urine in the first 20 h. Kidney, liver, spleen, and bone marrow activity uptake was observed in all patients. Tumor was not visualized in the first 3 patients but could be localized by tomoscintigraphy in the pancreas head region of patient 4. In vitro tissue analysis showed high expression of NT receptor in the tumor of patient 4, correlated with the highest tumor radioactivity uptake and the highest tumor-to-fat radioactivity ratio. In vitro receptor expression was also positive in a second patient having a tumor characterized by very low cellularity; however, the remaining 2 tumors lacked NT receptor expression.


CONCLUSIONS
Injection of (99m)Tc-NT-XI was well tolerated. The in vivo tumor uptake appeared specific as it was observed in the 1 patient with a pancreatic tumor that expressed high amounts of NT receptor. The results are compatible with preclinical animal results and in favor of further development of radiolabeled NT analogs for diagnosis or therapy of cancer.
Buchegger
Franz
F
Division of Nuclear Medicine, University Hospital of Lausanne, Lausanne, Switzerland. Franz.Buchegger@chuv.hospvd.ch
Bonvin
Florent
F
Kosinski
Marek
M
Schaffland
Andreas O
AO
Prior
John
J
Reubi
Jean C
JC
Bläuenstein
Peter
P
Tourwé
Dirk
D
García Garayoa
Elisa
E
Bischof Delaloye
Angelika
A
D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000378:metabolism; D000328:Adult; D000368:Aged; D021441:Carcinoma, Pancreatic Ductal / Q000000981:diagnostic imaging* / Q000378:metabolism*; D005260:Female; D006207:Half-Life; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D009496:Neurotensin / Q000031:analogs & derivatives / Q000493:pharmacokinetics*; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics*; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism*; D011237:Predictive Value of Tests; D011829:Radiation Dosage; D011874:Radiometry; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D014915:Whole-Body Counting
D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C479804:technetium Tc 99m NT-XI; D009496:Neurotensin