A radioligand is a microscopic particle which consists of a therapeutic radioactive isotope and the cell-targeting compound - the ligand. The ligand is the target binding site, it may be on the surface of the targeted cancer cell for therapeutic purposes. Radioisotopes can occur naturally or be synthesized and produced in a cyclotron/nuclear reactor. The different types of radioisotopes include Y-90, H-3, C-11, Lu-177, Ac-225, Ra-223, In-111, I-131, I-125, etc. Thus, radioligands must be produced in special nuclear reactors for the radioisotope to remain stable. Radioligands can be used to analyze/characterize receptors, to perform binding assays, to help in diagnostic imaging, and to provide targeted cancer therapy. Radiation is a novel method of treating cancer and is effective in short distances along with being unique/personalizable and causing minimal harm to normal surrounding cells. Furthermore, radioligand binding can provide information about receptor-ligand interactions in vitro and in vivo. Choosing the right radioligand for the desired application is important. The radioligand must be radiochemically pure, stable, and demonstrate a high degree of selectivity, and high affinity for their target.
90Y-DOTA-biotin consists of a radioactive substance (yttrium-90) complexed by a chelating agent (DOTA), which in turn is attached to the vitamin biotin via a chemical linker. It is used experimentally in pretargeted radioimmunotherapy. Animal studies have been conducted as well as clinical studies in humans.
Octreotide, sold under the brand name Sandostatin among others, is an octapeptide that mimics natural somatostatin pharmacologically, though it is a more potent inhibitor of growth hormone, glucagon, and insulin than the natural hormone. It was first synthesized in 1979 by the chemist Wilfried Bauer, and binds predominantly to the somatostatin receptors SSTR2 and SSTR5.
Neuroblastoma (NB) is a type of cancer that forms in certain types of nerve tissue. It most frequently starts from one of the adrenal glands but can also develop in the head, neck, chest, abdomen, or spine. Symptoms may include bone pain, a lump in the abdomen, neck, or chest, or a painless bluish lump under the skin.
A carcinoid is a slow-growing type of neuroendocrine tumor originating in the cells of the neuroendocrine system. In some cases, metastasis may occur. Carcinoid tumors of the midgut are associated with carcinoid syndrome.
Carcinoid syndrome is a paraneoplastic syndrome comprising the signs and symptoms that occur secondary to neuroendocrine tumors. The syndrome is caused by neuroendocrine tumors most often found in the gut releasing biologically active substances into the blood causing symptoms such as flushing and diarrhea, and less frequently, heart failure, vomiting and bronchoconstriction.
A VIPoma or vipoma is a rare endocrine tumor that overproduces vasoactive intestinal peptide. The incidence is about 1 per 10,000,000 per year. VIPomas usually originate from the non-β islet cells of the pancreas. They are sometimes associated with multiple endocrine neoplasia type 1. Roughly 50–75% of VIPomas are malignant, but even when they are benign, they are problematic because they tend to cause a specific syndrome: the massive amounts of VIP cause a syndrome of profound and chronic watery diarrhea and resultant dehydration, hypokalemia, achlorhydria, acidosis, flushing and hypotension, hypercalcemia, and hyperglycemia. This syndrome is called Verner–Morrison syndrome (VMS), WDHA syndrome, or pancreatic cholera syndrome (PCS). The eponym reflects the physicians who first described the syndrome.
A gallium scan is a type of nuclear medicine test that uses either a gallium-67 (67Ga) or gallium-68 (68Ga) radiopharmaceutical to obtain images of a specific type of tissue, or disease state of tissue. Gallium salts like gallium citrate and gallium nitrate may be used. The form of salt is not important, since it is the freely dissolved gallium ion Ga3+ which is active. Both 67Ga and 68Ga salts have similar uptake mechanisms. Gallium can also be used in other forms, for example 68Ga-PSMA is used for cancer imaging. The gamma emission of gallium-67 is imaged by a gamma camera, while the positron emission of gallium-68 is imaged by positron emission tomography (PET).
Neuroendocrine tumors (NETs) are neoplasms that arise from cells of the endocrine (hormonal) and nervous systems. They most commonly occur in the intestine, where they are often called carcinoid tumors, but they are also found in the pancreas, lung, and the rest of the body.
An octreotide scan is a type of SPECT scintigraphy used to find carcinoid, pancreatic neuroendocrine tumors, and to localize sarcoidosis. It is also called somatostatin receptor scintigraphy (SRS). Octreotide, a drug similar to somatostatin, is radiolabeled with indium-111, and is injected into a vein and travels through the bloodstream. The radioactive octreotide attaches to tumor cells that have receptors for somatostatin. A gamma camera detects the radioactive octreotide, and makes pictures showing where the tumor cells are in the body, typically by a SPECT technique. A technetium-99m based radiopharmaceutical kit is also available.
DOTA (also known as tetraxetan) is an organic compound with the formula (CH2CH2NCH2CO2H)4. The molecule consists of a central 12-membered tetraaza (i.e., containing four nitrogen atoms) ring. DOTA is used as a complexing agent, especially for lanthanide ions. Its complexes have medical applications as contrast agents and cancer treatments.
Indium-111 (111In) is a radioactive isotope of indium (In). It decays by electron capture to stable cadmium-111 with a half-life of 2.8 days. Indium-111 chloride (111InCl) solution is produced by proton irradiation of a cadmium target in a cyclotron, as recommended by International Atomic Energy Agency (IAEA). The former method is more commonly used as it results in a high level of radionuclide purity.
DOTA-TATE is an eight amino acid long peptide, with a covalently bonded DOTA bifunctional chelator.
Advanced Accelerator Applications is a France-based pharmaceutical group, specialized in the field of nuclear medicine. The group operates in all three segments of nuclear medicine to diagnose and treat serious conditions in the fields of oncology, neurology, cardiology, infectious and inflammatory diseases.
Matthew Kulke is an American cancer researcher. He is the Chief of Hematology/Oncology, co-director of the BU/BMC Cancer Center and "Zoltan Kohn Professor" at the Boston University School of Medicine. His work has shed light on the molecular characteristics of neuroendocrine tumors and has led to the development of multiple new treatments for this condition. His research studies led to the development and approval of telotristat ethyl, a tryptophan hydroxylase inhibitor, for the treatment of patients with carcinoid syndrome. He has also contributed to early and late stage clinical trials of temozolomide, sunitinib, everolimus, and peptide receptor radiotherapy for neuroendocrine tumors.
Peptide receptor radionuclide therapy (PRRT) is a type of radionuclide therapy, using a radiopharmaceutical that targets peptide receptors to deliver localised treatment, typically for neuroendocrine tumours (NETs).
Lutetium (177Lu) oxodotreotide (INN) or 177Lu dotatate, brand name Lutathera, is a chelated complex of a radioisotope of the element lutetium with dotatate, used in peptide receptor radionuclide therapy. Specifically, it is used in the treatment of cancers which express somatostatin receptors. It is a radiolabeled somatostatin analog.
Lutetium (177Lu) vipivotide tetraxetan, sold under the brand name Pluvicto, is a radiopharmaceutical medication used for the treatment of prostate-specific membrane antigen (PSMA)-positive metastatic castration-resistant prostate cancer (mCRPC). Lutetium (177Lu) vipivotide tetraxetan is a targeted radioligand therapy.
Somatostatin receptor antagonists are a class of chemical compounds that work by imitating the structure of the neuropeptide somatostatin. The somatostatin receptors are G protein-coupled receptors. Somatostatin receptor subtypes in humans are sstr1, 2A, 2 B, 3, 4 and 5. While normally expressed in the gastrointestinal (GI) tract, pancreas, hypothalamus, and central nervous system (CNS), they are expressed in different types of tumours. The predominant subtype in cancer cells is the ssrt2 subtype, which is expressed in neuroblastomas, meningiomas, medulloblastomas, breast carcinomas, lymphomas, renal cell carcinomas, paragangliomas, small cell lung carcinomas and hepatocellular carcinomas.
Somatostatin receptor antagonists are a class of chemical compounds that work by imitating the structure of the neuropeptide somatostatin, which is an endogenous hormone found in the human body. The somatostatin receptors are G protein-coupled receptors. Somatostatin receptor subtypes in humans include sstr1, 2A, 2 B, 3, 4, and 5. While normally expressed in the gastrointestinal (GI) tract, pancreas, hypothalamus, and central nervous system (CNS), they are expressed in different types of tumours. The predominant subtype in cancer cells is the ssrt2 subtype, which is expressed in neuroblastomas, meningiomas, medulloblastomas, breast carcinomas, lymphomas, renal cell carcinomas, paragangliomas, small cell lung carcinomas, and hepatocellular carcinomas.
