Evaluation of the therapeutic response to In-111-DTPA octreotide-based targeted therapy in liver metastatic neuroendocrine tumors according to CT/MRI/US findings

Thirteen (13) patients with liver neuroendocrine carcinomas metastases, positive for somatostatin receptors, confirmed by scintigraphy were infused with 4070-7030 MBq per session of In-111-octreotide after selective hepatic catheterization, exploiting the catastrophic activity of Indium Auger and Internal Conversion electron emission on cell DNA. Evaluation of the treatment was assessed by ultrasonography (US) as well as by computed tomography and/or magnetic resonance imaging scans. US appears to be the imaging procedure of choice because the examination is sensitive for evaluating lesions' edema and cystic components, provides precise measurement of tumor size, and is inexpensive. Degeneration US signs were classified in stage IIb (an echolucent rim in the periphery of the lesion), stage IIa (lesion with large cystic spaces), stage IIb (tiny cystic spaces) and stage III (absorption of the cystic component or stable cystic remnants). © Mary Ann Liebert, Inc

Comparison of 111in-[DTPA]octreotide versus non carrier added 177Lu-[DOTA,Tyr3]-octreotate efficacy in patients with GEP-NET treated intra-arterially for liver metastases

Aim: In patients with progressive, metastatic neuroendocrine tumors (NET), intra-arterial radionuclide infusions with high activities of 111In-[DTPA]-octreotide and more recently with non-carrier added (nca) 177Lu-[DOTA, Tyr3]-octreotate have been performed with encouraging results. However, the affinity profiles (IC50) of these radiopeptides for human sst2 receptors are markedly different (111In-[DTPA]-octreotide, 22 ± 3.6 nM and nca 177Lu-[DOTA,Tyr3]-octreotate, 1.5 ± 4.0 nM). The total administered activity is determined by organ dose limits (kidneys and bone marrow), and our aim therefore was to compare and evaluate the therapeutic efficacy of both radiopeptides in metastatic NETs. Methods: Thirty patients with gastroenteropancreatic (GEP) somatostatinpositive NETs with liver metastases confirmed on biopsy and 111In-pentetreotide scan were included. They were treated with 111In-[DTPA]-octreotide (n = 17) or nca 177Lu-[DOTA,Tyr3]-octreotate (n = 13). Blood samples were collected 2, 4, 8, and 24 hours postadministration to calculate residence time in blood and in red marrow. The maximum percentage uptake in organs and tumors was estimated by region of interest analysis, and tumor dosimetry calculations were performed using OLINDA/EXM/1.0 software. Results: nca177Lu-[DOTA,Tyr3]-octreotate blood radioactivity, expressed as a percentage of the injected dose, was significantly lower than 111In-[DTPA]-octreotide (P < 0.05), as clearly depicted from the time-activity curves; the background-corrected tumor uptake was significantly higher than 111In-[DTPA]-octreotide but without any significant difference in other organs (spleen, kidneys, and liver). Conclusions: Using 177Lu-[DOTA,Tyr3]-octreotate, a 3-fold higher absorbed dose to tumor tissue was achieved compared with 111In-[DTPA] octreotide. Residence time of nca 177Lu-[DOTA,Tyr3]-octreotate results in a significantly higher absorbed dose to bone marrow compared with 111In-[DTPA]-octreotide. However, a drawback of 111In-[DTPA]-octreotide therapy is that the number of administrations would need to be almost doubled to achieve an equal therapeutic outcome as compared with 177Lu-[DOTA, Tyr3]-octreotate. © 2015 Wolters Kluwer Health, Inc. All rights reserved