114mIn, a candidate for radionuclide therapy: low-energy cyclotron production and labeling of DTPA-D-phe-octreotide.
A method for production of carrier-free (114m)In (half-life 49.5 days), which is a potential radionuclide for radionuclide therapy of slowly growing tumors, is presented. A target consisting of five enriched cadmium ((114)Cd) foils, each 50 microm thick, was irradiated by protons (from 12.6-6.5 MeV) giving a target yield of 0. 8 MBq/microAh. A simple and cost-efficient thermal diffusion method was used for the separation. The irradiated target foils were heated for 2 h at 306 degrees C and then etched in 0.05 M HCl. The obtained cadmium/indium solution was purified using a cation ion-exchange resin (AG 1 x 8, Bio-Rad Laboratories, Hercules, CA USA). An overall yield of approximately 60% was obtained, whereas the loss of the target material was <1% per separation cycle. The (114m)In production gave (114m)In with high specific radioactivity and was successfully used to label diethylenetriamine pentaacetic acid (DTPA)-D-Phe-octreotide. Furthermore, no difference in biodistribution between [(114m)In]- and [(111)In]-DTPA-D-Phe(1)-octreotide in tumor-bearing nude mice was seen. The high radionuclide uptake in the tumors indicates a good receptor binding of the labeled octreotide.
Tolmachev
V
V
Division of Biomedical Radiation Sciences, Rudbecklaboratoriet, Uppsala University, Uppsala, Sweden. Vladimir.Tolmachev@bms.uu.se
Bernhardt
P
P
Forssell-Aronsson
E
E
Lundqvist
H
H
D000818:Animals; D002106:Cadmium Radioisotopes; D017357:Cyclotrons; D007205:Indium Radioisotopes / Q000627:therapeutic use; D007553:Isotope Labeling; D051379:Mice; D008819:Mice, Nude; D018358:Neuroendocrine Tumors / Q000532:radiotherapy*; D015282:Octreotide / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000493:pharmacokinetics / Q000627:therapeutic use; D004369:Pentetic Acid / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000493:pharmacokinetics / Q000627:therapeutic use; D011522:Protons; D019275:Radiopharmaceuticals / Q000138:chemical synthesis* / Q000493:pharmacokinetics / Q000627:therapeutic use*; D014018:Tissue Distribution
D002106:Cadmium Radioisotopes; D007205:Indium Radioisotopes; D011522:Protons; D019275:Radiopharmaceuticals; C071632:SDZ 215-811; D004369:Pentetic Acid; D015282:Octreotide