%0 Comparative Study
%T Comparison of somatostatin receptor agonist and antagonist for peptide receptor radionuclide therapy: a pilot study.
%A Wild D
%A Fani M
%A Fischer R
%A Del Pozzo L
%A Kaul F
%A Krebs S
%A Fischer R
%A Rivier JE
%A Reubi JC
%A Maecke HR
%A Weber WA
%J J Nucl Med
%V 55
%N 8
%D Aug 2014
%M 24963127
%F 11.082
%R 10.2967/jnumed.114.138834
%X Preclinical and clinical studies have indicated that somatostatin receptor (sst)-expressing tumors demonstrate higher uptake of radiolabeled sst antagonists than of sst agonists. In 4 consecutive patients with advanced neuroendocrine tumors, we evaluated whether treatment with (177)Lu-labeled sst antagonists is feasible.<BR><B>METHODS: </B>After injection of approximately 1 GBq of (177)Lu-DOTA-[Cpa-c(DCys-Aph(Hor)-DAph(Cbm)-Lys-Thr-Cys)-DTyr-NH2] ((177)Lu-DOTA-JR11) and (177)Lu-DOTATATE, 3-dimensional voxel dosimetry analysis based on SPECT/CT was performed. A higher tumor-to-organ dose ratio for (177)Lu-DOTA-JR11 than for (177)Lu-DOTATATE was the prerequisite for treatment with (177)Lu-DOTA-JR11.<BR><B>RESULTS: </B>Reversible minor adverse effects of (177)Lu-DOTA-JR11 were observed. (177)Lu-DOTA-JR11 showed a 1.7-10.6 times higher tumor dose than (177)Lu-DOTATATE. At the same time, the tumor-to-kidney and tumor-to-bone marrow dose ratio was 1.1-7.2 times higher. All 4 patients were treated with (177)Lu-DOTA-JR11, resulting in partial remission in 2 patients, stable disease in 1 patient, and mixed response in the other patient.<BR><B>CONCLUSIONS: </B>Treatment of neuroendocrine tumors with radiolabeled sst antagonists is clinically feasible and may have a significant impact on peptide receptor radionuclide therapy.