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K Nazar A, Basu S. Radiolabeled Somatostatin Analogs for Cancer Imaging. Semin Nucl Med 2024:S0001-2998(24)00058-8. [PMID: 39122608 DOI: 10.1053/j.semnuclmed.2024.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2024] [Accepted: 07/01/2024] [Indexed: 08/12/2024]
Abstract
Somatostatin receptors (SSTR) are expressed by many tumours especially those related to neuro-endocrine origin and molecular functional imaging of SSTR expression using radiolabelled somatostatin analogs have revolutionized imaging of patients with these group of malignancies. Coming a long way from the first radiolabelled somatostatin analog 123I-Tyr-3-octreotide, there has been significant developments in terms of radionuclides used, the ligands and somatostatin derivatives. 111In-Pentetreotide extensively employed for imaging NETs at the beginning has now been replaced by 68Ga-SSA based PET-CT. SSA-PET/CT performs superior to conventional imaging modalities and has evolved in the mainframe for NET imaging. The advantages were multiple: (i) superior spatial resolution of PET versus SPECT, (ii) quantitative capabilities of PET aiding in disease activity and treatment response monitoring with better precision, (iii) shorter scan time and (iv) less patient exposure to radiation. The modality is indicated for staging, detecting the primary in CUP-NETs, restaging, treatment planning (along with FDG: the concept of dual-tracer PET-CT) as well as treatment response evaluation and follow-up of NETs. SSA PET/CT has also been incorporated in the guidelines for imaging of Pheochromocytoma-Paraganglioma, Medullary carcinoma thyroid, Meningioma and Tumor induced osteomalacia. At present, there is rising interest on (a) 18F-labelled SSA, (b) 64Cu-labelled SSA, and (c) somatostatin antagonists. 18F offers excellent imaging properties, 64Cu makes delayed imaging feasible which has implications in dosimetry and SSTR antagonists bind with the SST receptors with high affinity and specificity, providing high contrast images with less background, which can be translated to theranostics effectively. SSTR have been demonstrated in non-neuroendocrine tumours as well in the peer-reviewed literature, with studies demonstrating the potential of SSA PET/CT in Neuroblastoma, Nasopharyngeal carcinoma, carcinoma prostate (neuroendocrine differentiation) and lymphoma. This review will focus on the currently available SSAs and their history, different SPECT/PET agents, SSTR antagonists, comparison between the various imaging tracers, and their utility in both neuroendocrine and non-neuroendocrine tumors.
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Affiliation(s)
- Aamir K Nazar
- Radiation Medicine Centre, Bhabha Atomic Research Centre, Tata Memorial Centre Annexe, Mumbai; Homi Bhabha National Institute, Mumbai
| | - Sandip Basu
- Radiation Medicine Centre, Bhabha Atomic Research Centre, Tata Memorial Centre Annexe, Mumbai; Homi Bhabha National Institute, Mumbai.
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Liu F, Liu T, Xu X, Guo X, Li N, Xiong C, Li C, Zhu H, Yang Z. Design, Synthesis, and Biological Evaluation of 68Ga-DOTA-PA1 for Lung Cancer: A Novel PET Tracer for Multiple Somatostatin Receptor Imaging. Mol Pharm 2018; 15:619-628. [PMID: 29278911 DOI: 10.1021/acs.molpharmaceut.7b00963] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Most of the radiolabeled somatostatin analogues (SSAs) are specific for subtype somatostatin receptor 2 (SSTR2). Lack of ligands targeting other subtypes of SSTRs, especially SSTR1, SSTR3, and SSTR5, limited their applications in tumors of low SSTR2 expression, including lung tumor. In this study, we aimed to design and synthesize a positron emission tomography (PET) radiotracer targeting multi-subtypes of SSTRs for PET imaging. PA1 peptide and its conjugate with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelator or fluorescein isothiocyanate (FITC) at the N-terminal of the lysine position were synthesized. 68Ga was chelated to DOTA-PA1 to obtain 68Ga-DOTA-PA1 radiotracer. The stability, lipophilicity, binding affinity, and binding specificity of 68Ga-DOTA-PA1 and FITC-PA1 were evaluated by various in vitro experiments. Micro-PET imaging of 68Ga-DOTA-PA1 was performed in nude mice bearing A549 lung adenocarcinoma, as compared with 68Ga-DOTA-(Tyr3)-octreotate (68Ga-DOTA-TATE). Histological analysis of SSTR expression in A549 tumor tissues and human tumor tissues was conducted using immunofluorescence staining and immunohistochemical assay. 68Ga-DOTA-PA1 had high radiochemical yield and radiochemical purity of over 95% and 99%, respectively. The radiotracer was stable in vitro in different buffers over a 2 h incubation period. Cell uptake of 68Ga-DOTA-PA1 was 1.31-, 1.33-, and 1.90-fold that of 68Ga-DOTA-TATE, which has high binding affinity only for SSTR2, after 2 h incubation in H520, PG, and A549 lung cancer cell lines, respectively. Micro-PET images of 68Ga-DOTA-PA1 showed that the PET imaging signal correlated with the total expression of SSTRs, instead of SSTR2 only, which was measured by Western blotting and immunofluorescence analysis in mice bearing A549 tumors. In summary, a novel PET radiotracer, 68Ga-DOTA-PA1, targeting multi-subtypes of SSTRs, was successfully synthesized and was confirmed to be useful for PET imaging. It may have potential as a noninvasive PET radiotracer for imaging SSTR-positive tumors.
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Affiliation(s)
- Fei Liu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute , Beijing 100142, P. R. China
| | - Teli Liu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute , Beijing 100142, P. R. China
| | - Xiaoxia Xu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute , Beijing 100142, P. R. China
| | - Xiaoyi Guo
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute , Beijing 100142, P. R. China
| | - Nan Li
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute , Beijing 100142, P. R. China
| | - Chiyi Xiong
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center , Houston, Texas 77030, United States
| | - Chun Li
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center , Houston, Texas 77030, United States
| | - Hua Zhu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute , Beijing 100142, P. R. China
| | - Zhi Yang
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute , Beijing 100142, P. R. China
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Sollini M, Erba PA, Fraternali A, Casali M, Di Paolo ML, Froio A, Frasoldati A, Versari A. PET and PET/CT with 68gallium-labeled somatostatin analogues in Non GEP-NETs Tumors. ScientificWorldJournal 2014; 2014:194123. [PMID: 24693229 PMCID: PMC3947736 DOI: 10.1155/2014/194123] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Accepted: 10/30/2013] [Indexed: 12/27/2022] Open
Abstract
Somatostatin (SST) is a 28-amino-acid cyclic neuropeptide mainly secreted by neurons and endocrine cells. A major interest for SST receptors (SSTR) as target for in vivo diagnostic and therapeutic purposes was born since a series of stable synthetic SST-analouges PET became available, being the native somatostatin non feasible for clinical use due to the very low metabolic stability. The rationale for the employment of SST-analogues to image cancer is both based on the expression of SSTR by tumor and on the high affinity of these compounds for SSTR. The primary indication of SST-analogues imaging is for neuroendocrine tumors (NETs), which usually express a high density of SSTR, so they can be effectively targeted and visualized with radiolabeled SST-analogues in vivo. Particularly, SST-analogues imaging has been widely employed in gastroenteropancreatic (GEP) NETs. Nevertheless, a variety of tumors other than NETs expresses SSTR thus SST-analogues imaging can also be used in these tumors, particularly if treatment with radiolabeled therapeutic SST-analouges PET is being considered. The aim of this paper is to provide a concise overview of the role of positron emission tomography/computed tomography (PET/CT) with (68)Ga-radiolabeled SST-analouges PET in tumors other than GEP-NETs.
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Affiliation(s)
- Martina Sollini
- Nuclear Medicine Unit, Arcispedale Santa Maria Nuova-IRCCS, Reggio Emilia, 42123 Reggio Emilia, Italy
| | - Paola Anna Erba
- Regional Center of Nuclear Medicine, University of Pisa, Arcispedale Santa Maria Nuova-IRCCS, Reggio Emilia, 56125 Pisa, Italy
| | - Alessandro Fraternali
- Nuclear Medicine Unit, Arcispedale Santa Maria Nuova-IRCCS, Reggio Emilia, 42123 Reggio Emilia, Italy
| | - Massimiliano Casali
- Nuclear Medicine Unit, Arcispedale Santa Maria Nuova-IRCCS, Reggio Emilia, 42123 Reggio Emilia, Italy
| | - Maria Liberata Di Paolo
- Nuclear Medicine Unit, Arcispedale Santa Maria Nuova-IRCCS, Reggio Emilia, 42123 Reggio Emilia, Italy
| | - Armando Froio
- Nuclear Medicine Unit, Arcispedale Santa Maria Nuova-IRCCS, Reggio Emilia, 42123 Reggio Emilia, Italy
| | - Andrea Frasoldati
- Endocrinology Unit, Arcispedale Santa Maria Nuova-IRCCS, Reggio Emilia, 42123 Reggio Emilia, Italy
| | - Annibale Versari
- Nuclear Medicine Unit, Arcispedale Santa Maria Nuova-IRCCS, Reggio Emilia, 42123 Reggio Emilia, Italy
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Sharma P, Singh H, Bal C, Kumar R. PET/CT imaging of neuroendocrine tumors with (68)Gallium-labeled somatostatin analogues: An overview and single institutional experience from India. Indian J Nucl Med 2014; 29:2-12. [PMID: 24591775 PMCID: PMC3928745 DOI: 10.4103/0972-3919.125760] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Neuroendocrine tumors (NETs) are rare neoplasms characterized by overexpression of somatostatin receptors (SSTRs). Functional imaging plays a crucial role in management of NETs. Recently, positron emission tomography/computed tomography (PET/CT) with (68)Gallium ((68)Ga)-labeled somatostatin analogues has shown excellent results for imaging of NETs and better results than conventional SSTR scintigraphy. In this review we have discussed the utility of (68)Ga-labeled somatostatin analogue PET/CT in NETs for various established and potential indications. In addition we have also shared our own experience from a tertiary care center in India.
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Key Words
- 68Gallium-labeled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-NaI3-octreotide
- 68Gallium-labeled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-Phe1-Tyr3-Octreotide
- 68Gallium-labeled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-Tyr3-Octreotate
- Neuroendocrine tumor
- PET/CT
- somatostatin receptor
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Affiliation(s)
- Punit Sharma
- Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Harmandeep Singh
- Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Chandrasekhar Bal
- Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Rakesh Kumar
- Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India
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