Priming increases the anti-tumor effect and therapeutic window of 177Lu-octreotate in nude mice bearing human small intestine neuroendocrine tumor GOT1

• Published in: EJNMMI research 2017-01, Vol.7 (1), p.6-6, Article 6
• Main Authors: Dalmo, Johanna, Spetz, Johan, Montelius, Mikael, Langen, Britta, Arvidsson, Yvonne, Johansson, Henrik, Parris, Toshima Z., Helou, Khalil, Wängberg, Bo, Nilsson, Ola, Ljungberg, Maria, Forssell-Aronsson, Eva
• Format: Article
• Language: English
• Subjects: 177Lu-DOTATATE; Cancer and Oncology; Cancer och onkologi; Cardiac Imaging; Cell and Molecular Biology; Cell- och molekylärbiologi; Fractionated radionuclide therapy; Gene expression; Imaging; Keywords: Neuroendocrine tumor; Medicine; Medicine & Public Health; MRI; Nuclear Medicine; Oncology; Original Research; Orthopedics; Radiation biology; Radiologi och bildbehandling; Radiology; Radiology, Nuclear Medicine and Medical Imaging; Somatostatin receptors; Xenograft model
• ISSN: 2191-219X; 2191-219X
• DOI: 10.1186/s13550-016-0247-y

Background 177 Lu-[DOTA 0 , Tyr 3 ]-octreotate ( 177 Lu-octreotate) is used for treatment of patients with somatostatin receptor (SSTR) expressing neuroendocrine tumors. However, complete tumor remission is rarely seen, and optimization of treatment protocols is needed. In vitro studies have shown that irradiation can up-regulate the expression of SSTR1 , 2 and 5 , and increase 177 Lu-octreotate uptake. The aim of the present study was to examine the anti-tumor effect of a 177 Lu-octreotate priming dose followed 24 h later by a second injection of 177 Lu-octreotate compared to a single administration of 177 Lu-octreotate, performed on the human small intestine neuroendocrine tumor cell line, GOT1, transplanted to nude mice. Results Priming resulted in a 1.9 times higher mean absorbed dose to the tumor tissue per administered activity, together with a reduced mean absorbed dose for kidneys. Priming gave the best overall anti-tumor effects. Magnetic resonance imaging showed no statistically significant difference in tumor response between treatment with and without priming. Gene expression analysis demonstrated effects on cell cycle regulation. Biological processes associated with apoptotic cell death were highly affected in the biodistribution and dosimetry study, via differential regulation of, e.g., APOE , BAX , CDKN1A , and GADD45A . Conclusions Priming had the best overall anti-tumor effects and also resulted in an increased therapeutic window. Results indicate that potential biomarkers for tumor regrowth may be found in the p53 or JNK signaling pathways. Priming administration is an interesting optimization strategy for 177 Lu-octreotate therapy of neuroendocrine tumors, and further studies should be performed to determine the mechanisms responsible for the reported effects.