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Machine Learning Approach to Overcome the Challenges in Theranostics
Published in Shampa Sen, Leonid Datta, Sayak Mitra, Machine Learning and IoT, 2018
Bishwambhar Mishra, Sayak Mitra, Karthikeya Srinivasa Varma Gottimukkala, Shampa Sen
The key theranostic players in nuclear medicine are the small molecules with covalently attached chelators for labeling with radiometals. The nuclide of Ga-68 is used as positron emitter in diagnosis and visualization of receptors or antigen expression. Peptide receptor radionuclide therapy (PRRT) is a theranostic approach mainly targets somatostatin receptor subtypes 2 (SSTR2) for the detection of neuroendocrine tumors (NET). Peptides are covalently bound to the chelator DOTA (1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid), which enables the coordination of Ga-68 for PET imaging and Lu-177 (and Y-90) for radiotherapy. The ability of all these derivatives to address somatostatin receptor expression is comparable to neuroendocrine tumors (Blankenberg and Strauss 2012; Maecke and Reubi 2017).
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 somatostatin receptor (SSTR) is a transmembrane, G-protein-coupled receptor that is expressed by neuroendocrine cells present in most tissues and organs throughout the body. NETs, being tumours made up of neuroendocrine cells, have an especially high receptor density. There are five subtypes of the SSTR, and different tissues express different combinations of receptor subtypes. The natural ligand, somatostatin, is a hormone secreted by the hypothalamus, whose function is to inhibit the hormonal secretion from neuroendocrine cells [2]. The same effect can be achieved through injection of a synthetic analogue of somatostatin (SSA), which has been used since the 1980s to treat acromegaly (hypersecretion of growth hormone) and NETs.
Targeted Delivery Systems Based on Polymeric Nanoparticles for Biomedical Applications
Published in Anil K. Sharma, Raj K. Keservani, Rajesh K. Kesharwani, Nanobiomaterials, 2018
Sa Yang, Can Huang, Zhi-Ping Li, Qian Ning, Wen Huang, Wen-Qin Wang, Cui-Yun Yu
Besides, somatostatin (SST) also widely used in drug delivery. SST is a neuropeptide that demonstrate powerful inhibitory effect against several endocrine systems. SST was originally isolated as an endocrine inhibitor of pituitary growth hormone secretion and is now recognized as a hormone capable of regulating fundamental processes, such as secretion, cell division, proliferation and apoptosis (Narayanan et al., 2016; Mariniello et al., 2011). The cellular actions of SST are mediated by five somatostatin receptor subtypes (termed SSTR 1–5). SST’s therapeutic applications are limited due to its short half-life and various synthetic Somatostatin analogs (SSTA) such as octreotide, lanreotide, vapreotide, etc. have been developed successfully by shortening the sequence and introducing D-amino acids to replace natural L-amino acids, improved metabolic stability and increased affinity to SSTRs (Mulvey et al., 2016; Liapakis et al., 1996; Karashima et al., 1987; Lesche et al., 2009). Octreotide was the first SSA developed for clinical application. It was approved in 1988 for palliation of carcinoid syndrome as well as other hormonal syndromes caused by metastatic gastroenteropancreatic (GEP)-NETs including vasoactive intestinal peptide-producing tumors. Apart from OCT, other long-acting SSTAs have been synthesized and investigated in vitro and in vivo. Lanreotide was licensed in Europe in 1998 for the treatment of symptoms associated with advanced neuroendocrine tumors (Raderer et al., 1999; Kvols et al., 1986; Narayanan et al., 2015; O’Toole et al., 2000). There are other SSTAs such as Vapreotide, pasireotide, SST dicarba-analog 11 and 14, etc. These SSTAs have been widely used to treat various tumors, particularly endocrine tumors.
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).