Targeting peptides for pleural cavity tumor radiotherapy: specificity and dosimetry of Re-188-RC-160.
Re-188-RC-160, a radiolabeled somatostatin analogue, is being explored for its potential as a local/regionally administered radiotherapeutic agent targeting somatostatin receptor-positive tumors. In studies in vitro and in vivo, Re-188-RC-160 was found to bind to somatostatin receptor-positive cells (NCI-H69, human small cell lung carcinoma), but not to binding-negative cells (Raji, Burkitt's lymphoma). The comparative binding of Re-188-labeled RC-160 [cyclic NH2-(D)-Phe-Cys-Try-(D)-Trp-Lys-Val-Cys-Trp-NH2] or CTOP [cyclic NH2-(D)-Phe-Cys-Try-(D)-Trp-Orn-Thr-Pen-Thr-ol], a mu-opioid receptor antagonist used a negative control compound, was also determined in vitro and in vivo using NCI-H69 cells as targets. Re-188-RC-160 demonstrated higher net binding in vitro and in vivo compared to Re-188-RC-CTOP, and in vitro its binding could be reduced by excess unlabeled RC-160 whereas binding of Re-188-CTOP could not be reduced. Using another somatostatin receptor-positive human tumor line, ZR-75-1, a substantial amount of the cell-bound Re-188-RC-160 was found to be internalized. Does estimates for Re-188-RC-160 in animals containing NCI-H69 tumors indicated that with three serial injections therapeutic doses greater than 60 Gy can be achieved.
Zamora
P O
PO
Department of Nuclear Medicine, University of Bonn, Germany.
Bender
H
H
Knapp
F F
FF
Rhodes
B A
BA
Biersack
H J
HJ
D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000737:chemistry / Q000627:therapeutic use; D018288:Carcinoma, Small Cell / Q000378:metabolism / Q000532:radiotherapy; D016503:Drug Delivery Systems; D006207:Half-Life; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy*; D011485:Protein Binding; D011868:Radioisotopes / Q000008:administration & dosage* / Q000627:therapeutic use; D017481:Receptors, Somatostatin / Q000378:metabolism; D012211:Rhenium / Q000008:administration & dosage*; D013004:Somatostatin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry / Q000627:therapeutic use
D000970:Antineoplastic Agents; D011868:Radioisotopes; D017481:Receptors, Somatostatin; C049352:phenylalanyl-cyclo(cysteinyltyrosyl-tryptophyl-ornithyl-threonyl-penicillamine)threoninamide; C051458:vapreotide; D013004:Somatostatin; D012211:Rhenium