RT Journal Article SR Electronic T1 Comparison of Somatostatin Receptor Agonist and Antagonist for Peptide Receptor Radionuclide Therapy: A Pilot Study JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1248 OP 1252 DO 10.2967/jnumed.114.138834 VO 55 IS 8 A1 Wild, Damian A1 Fani, Melpomeni A1 Fischer, Richard A1 Del Pozzo, Luigi A1 Kaul, Felix A1 Krebs, Simone A1 Fischer, Richard A1 Rivier, Jean E.F. A1 Reubi, Jean Claude A1 Maecke, Helmut R. A1 Weber, Wolfgang A. YR 2014 UL http://jnm.snmjournals.org/content/55/8/1248.abstract AB 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 177Lu-labeled sst antagonists is feasible. Methods: After injection of approximately 1 GBq of 177Lu-DOTA-[Cpa-c(DCys-Aph(Hor)-DAph(Cbm)-Lys-Thr-Cys)-DTyr-NH2] (177Lu-DOTA-JR11) and 177Lu-DOTATATE, 3-dimensional voxel dosimetry analysis based on SPECT/CT was performed. A higher tumor-to-organ dose ratio for 177Lu-DOTA-JR11 than for 177Lu-DOTATATE was the prerequisite for treatment with 177Lu-DOTA-JR11. Results: Reversible minor adverse effects of 177Lu-DOTA-JR11 were observed. 177Lu-DOTA-JR11 showed a 1.7–10.6 times higher tumor dose than 177Lu-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 177Lu-DOTA-JR11, resulting in partial remission in 2 patients, stable disease in 1 patient, and mixed response in the other patient. Conclusion: Treatment of neuroendocrine tumors with radiolabeled sst antagonists is clinically feasible and may have a significant impact on peptide receptor radionuclide therapy.