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Peptide Receptor Radionuclide Therapy for Neuroendocrine Tumours
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Anna Sundlöv, Katarina Sjögreen Gleisner
The advent of the radiolabelled synthetic SSAs led to the development of the diagnostic nuclear medicine method of somatostatin receptor scintigraphy using 111In (Indium). Since 111In emits Auger electrons in its radioactive decay, it can potentially be used for therapeutic purposes. The first trials in humans with high injected activities of 111In-pentreotide demonstrated a small but encouraging therapeutic effect [6]. Currently, SSTR scintigraphy is rapidly being replaced by SSTR PET/CT using 68Ga (Gallium)-labelled DOTA-TOC or DOTA-TATE, which is used not only for staging of NET, but also for selection of patients for PRRT (Figure 1). For therapeutic purposes, the real breakthrough was the development of DOTA-chelated, beta-emitter labelled compounds such as 90Y-DOTA-TOC and 177Lu-DOTA-TATE, the latter being the compound that has reached the widest clinical use. The safety and efficacy of 177Lu-DOTA-TATE vis a vis standard therapy (high-dose octreotide) was demonstrated in the phase III trial NETTER-1: The patients in the PRRT arm reached a median progression-free survival (mPFS) of 28 months, whereas those in the control arm had a mPFS of only 8 months [7]. Based on these results, PRRT with 177Lu-DOTA-TATE was approved by the European Medicines Agency and the US Food and Drug Administration for the treatment of gastro-entero-pancreatic NETs.
Radiolabeled Agents for Molecular Imaging and/or Therapy
Published in George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos, Handbook of Small Animal Imaging, 2018
Dimitrios Psimadas, Eirini A. Fragogeorgi
In order to develop metabolically stable peptide analogs for molecular imaging and given the fact that SST have a plasma half-life of 3 min, introduction of D-amino acids and shortening of the molecule to the bioactive core sequence resulted in eight amino acid–containing SST analogs, such as octreotide (OC). The first commercially available agent was 111In-pentetreotide for sstr scintigraphy (OctreoScan®). However, this radiopeptide has moderate binding affinity to sstr2 and is not a suitable chelator for β-emitters complexation. The modified OC analogs N, N′,N″,N′″-tetraacetic acid (DOTA)-TOC and DOTA-TATE, labeled with 111In and 68Ga for SPECT and PET imaging respectively, and with 90Y and 177Lu for targeted radionuclide therapy, are routinely used in many hospitals. 99mTc, 18F, and 64Cu-labeled OC analogs have also been developed and are promising for SPECT and PET imaging clinical application (Fani and Maecke 2012).
Nuclear Medicine in Oncology
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2018
Carla Oliveira, Rui Parafita, Ana Canudo, Joana Correia Castanheira, Durval C. Costa
Tumours with a high expression of somatostatin receptors are potential targets for treatment with somatostatin analogue peptides (DOTATOC or DOTATATE) radiolabelled with emitters of beta minus particles (90Y or 177Lu). This treatment, which enables the generally partial destruction of these tumours, is not a first-order option, but constitutes an alternative for plurimetastasised or inoperable tumours, when all other conventional strategies are exhausted. (Forrer et al. 2007; Zaknun et al. 2013).
Separation of Radiogallium from Zinc Using Membrane-Based Liquid-Liquid Extraction in Flow: Experimental and COSMO-RS Studies
Published in Solvent Extraction and Ion Exchange, 2019
Kristina Søborg Pedersen, Karin Michaelsen Nielsen, Jesper Fonslet, Mikael Jensen, Fedor Zhuravlev
Radiogallium (66,67,68Ga = *Ga) has a long and notable history in nuclear medicine. For years, gallium-67 (67Ga, t1/2 = 78 h) scintigraphy has been a linchpin of molecular imaging of cancer,[1] including non-Hodgkin’s lymphoma, Hodgkin’s disease,[2] as well as various infections.[3] The advancement of positron emission tomography (PET) and FDA’s approval of [68Ga]Ga-DOTA-TATE (Netspot®) moved gallium-68 (68Ga, t1/2 = 68 min) to the forefront of neuroendocrine tumor diagnostics.[4] In recent years [68Ga]Ga-HBED-PSMA-11, a 68Ga-labeled PSMA (prostate-specific membrane antigen) ligand emerged as the gold standard for prostate cancer diagnostics, driving a high adoption rate of 68Ga in clinics.[5] The easy chelation chemistry and convenience of 68Ge/68Ga-generators further contribute to 68Ga popularity in clinical and pre-clinical settings.[6] Meeting the growing demand for 68Ga is a challenge, as it is mostly supplied by the gallium generators which suffer from high prices, long lead time, quality inconsistencies, and limited shelf life.[7] An alternative method of 68Ga production is the irradiation of 68Zn using a cyclotron.[8] Since many PET-centers have their own cyclotrons, this is potentially a convenient means of in-house production of 68Ga-tracers. However, the cyclotron production of 68Ga in solid targets from 68Zn and its subsequent separation require either installation of expensive automated solid target systems or requires a series of manual pre- and post-irradiation target handlings. Recently, the production of 68Ga in liquid targets from enriched 68Zn salt solutions has been described, using either [68Zn]ZnCl2[9,10] or [68Zn]Zn(NO3)2.[11–13] Compared to the solid target production, the solution target approach leads to lower radionuclide yields but has an advantage of being more amenable to automation. Currently, all 68Ga made in cyclotron solution targets is produced in batch mode; the desired radionuclide is subsequently purified from the 68Zn salt solution by solid-phase extraction (SPE) using commercial radiosynthesis modules, without directly recycling the 68Zn. If recycling of isotopically enriched 68Zn target material is desired, reprocessing needs to be performed in a separate step.