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IUPAC name N-((2S,3R,E)-1-(((2R,3R,4R,5S,6R)-5-(((2S,3R,4R,5R,6R)-5-(((2R,3R,4S,5S,6R)-4-(((2S,3R,4R,5R,6R)-3-acetamido-4-(((2R,3R,4S,5R,6R)-4,5-dihydroxy-6-(hydroxymethyl)-3-(((2S,3S,4R,5S,6S)-3,4,5-trihydroxy-6-methyltetrahydro-2H-pyran-2-yl)oxy)tetrahydro-2H-pyran-2-yl)oxy)-5-hydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)oxy)-3,5-dihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)oxy)-3,4-dihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)oxy)-3,4-dihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)oxy)-3-hydroxyoctadec-4-en-2-yl)palmitamide | |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Globo H (globohexaosylceramide) is a globo-series glycosphingolipid antigen that is present on the outer membrane of some cancer cells. [1] [2] Globo H is not expressed in normal tissue cells, but is expressed in a number of types of cancers, including cancers of the breast, prostate, and pancreas. [1] [3] Globo H's exclusivity for cancer cells makes it a target of interest for cancer therapies. [1] [2]
Defined by the monoclonal antibody MBr1, Globo H has been isolated from breast cancer cell line MCF-7, and its structure has been determined through several analyses, including NMR spectroscopy and methylation analysis. [5] Globo H consists of a hexasaccharide of the structure Fucα(1-2)Galβ(1-3)GalNAcβ(1-3)Galα(1-4)Galβ(1-4)Glcβ(1) with a ceramide attached to its terminal glucose ring at the 1 position in a beta linkage. [6]
Globo H's biosynthetic pathway is involved in the synthesis pathways of other globo-series glycosphingolipid antigens that are also specific to cancer cells, including stage-specific embryonic antigen-3 (SSEA3) and stage-specific embryonic antigen-4 (SSEA4). [1] The biosynthetic pathway of these antigens includes the enzyme β 1,3-galactosyltransferase V (β3GalT5). [1] β3GalT5 catalyzes the galactosylation of globoside-4 (Gb4) to SSEA3. [1] SSEA3 can then be converted to SSEA4 by sialyltransferase adding a sialic acid group to its end, or it can be converted to Globo H by fucosyltransferase adding a fucose ring to its end. [1] Playing a part in the formation of three different cancer-specific antigens, β3GalT5 is of particular interest in its relevance to cancer treatment, and it has been shown to be critical for cancer cell survival. [8]
In order to study its potential as a cancer therapy target, Globo H has been synthesized in the laboratory. [9] One synthesis is achieved by first building two trisaccharides from their component sugars, and then linking them. [9] The trisaccharides, with most of their functional groups protected to prevent side reactions, are linked by creating the GalNAcβ(1-3)Gal bond. [9] A thioethyl group is added to the 1 position on one of the protected galactose rings, and in the presence of methyl triflate, this reacts with the hydroxyl group on the 3 position of the other galactose to link the trisaccharides and form the hexasaccharide. [9] The ceramide is added to the 1 position of the terminal glucose ring after hexasaccharide formation. [9]
As a Tumor Associated Carbohydrate Antigen (TACA), Globo-H is a promising clinical target for immunotherapy. While absent in normal tissues, the glycosphingolipid is overexpressed in a variety of epithelial cancer cell types including human pancreatic, gastric, lung, colorectal, esophageal, and breast tumors. [10] [11]
Globo-H's TACA character allows for its utilization as an anticancer vaccine, inducing antibody response against the epitope. The resulting humoral immunity could enable the selective eradication of Globo H-presenting tumors. [12] The Taiwanese biopharma company OBI Pharma, Inc., was first to develop Adagloxad Simolenin (OBI-822), a Globo H hexasaccharide conjugated with the immunostimulatory carrier protein KLH. [12] The Phase III GLORIA study is underway evaluating the carbohydrate-based immunogen's effects in high risk triple-negative breast cancer (TNBC) patients with an estimated completion date in 2027. [13]
Alternative vaccine conjugates have been developed which avoid issues associated with the protein carrier KLH by substituting it with a lipid or carbohydrate-based carrier. Examples include the use of lipid A derivatives [14] or entirely carbohydrate vaccine conjugates such as Globo H-PS A1 [15]
Globo H-targeting antibodies are another strategy currently being evaluated in the cancer therapeutic space. OBI Pharma's OBI-888 is a humanized IgG1 antibody that selectively binds to the Globo H antigen among other Globo series glycosphingolipids such as SSEA-3 and SSEA-4. [16] Additionally, in vivo studies of OBI-888 in various Globo H-positive (GH+) xenografts models showed promising tumor growth inhibition results. [17] OBI-888's human Phase I/II study for the treatment of metastatic and locally advanced solid tumors is estimated to finish in December 2022. [18]
Based on OBI-888, the first-in-class antibody-drug conjugate (ADC) 0BI-999 was additionally developed, linking OBI-888 to monomethyl auristatin E, a synthetic antineoplastic agent. [19] The ADC is currently undergoing phase II trial in patients with advanced solid tumors, with an estimated completion date in Dec 2023. [20] In Dec 2019 & Jan 2020, OBI-999 was granted two Orphan Drug Designations by the FDA for the treatment of pancreatic and gastric cancer. [21]
Immunofluorescence(IF) is a light microscopy-based technique that allows detection and localization of a wide variety of target biomolecules within a cell or tissue at a quantitative level. The technique utilizes the binding specificity of antibodies and antigens. The specific region an antibody recognizes on an antigen is called an epitope. Several antibodies can recognize the same epitope but differ in their binding affinity. The antibody with the higher affinity for a specific epitope will surpass antibodies with a lower affinity for the same epitope.
Immunohistochemistry is a form of immunostaining. It involves the process of selectively identifying antigens (proteins) in cells and tissue, by exploiting the principle of antibodies binding specifically to antigens in biological tissues. Albert Hewett Coons, Ernest Berliner, Norman Jones and Hugh J Creech was the first to develop immunofluorescence in 1941. This led to the later development of immunohistochemistry.
Carcinoembryonic antigen (CEA) describes a set of highly-related glycoproteins involved in cell adhesion. CEA is normally produced in gastrointestinal tissue during fetal development, but the production stops before birth. Consequently, CEA is usually present at very low levels in the blood of healthy adults. However, the serum levels are raised in some types of cancer, which means that it can be used as a tumor marker in clinical tests. Serum levels can also be elevated in heavy smokers.
In biology, chimeric antigen receptors (CARs)—also known as chimeric immunoreceptors, chimeric T cell receptors or artificial T cell receptors—are receptor proteins that have been engineered to give T cells the new ability to target a specific antigen. The receptors are chimeric in that they combine both antigen-binding and T cell activating functions into a single receptor.
A single-domain antibody (sdAb), also known as a Nanobody, is an antibody fragment consisting of a single monomeric variable antibody domain. Like a whole antibody, it is able to bind selectively to a specific antigen. With a molecular weight of only 12–15 kDa, single-domain antibodies are much smaller than common antibodies which are composed of two heavy protein chains and two light chains, and even smaller than Fab fragments and single-chain variable fragments.
Targeted therapy or molecularly targeted therapy is one of the major modalities of medical treatment (pharmacotherapy) for cancer, others being hormonal therapy and cytotoxic chemotherapy. As a form of molecular medicine, targeted therapy blocks the growth of cancer cells by interfering with specific targeted molecules needed for carcinogenesis and tumor growth, rather than by simply interfering with all rapidly dividing cells. Because most agents for targeted therapy are biopharmaceuticals, the term biologic therapy is sometimes synonymous with targeted therapy when used in the context of cancer therapy. However, the modalities can be combined; antibody-drug conjugates combine biologic and cytotoxic mechanisms into one targeted therapy.
Chi-Huey Wong is a Taiwanese-American biochemist. He is currently the Scripps Family Chair Professor at the Scripps Research Institute. He is a member of the United States National Academy of Sciences, as awarded the 2014 Wolf Prize in Chemistry and 2015 RSC Robert Robinson Award. Wong is also the holder of more than 100 patents and publisher of 700 more scholarly academic research papers under his name.
Mesothelin, also known as MSLN, is a protein that in humans is encoded by the MSLN gene.
Mucin short variant S1, also called polymorphic epithelial mucin (PEM) or epithelial membrane antigen (EMA), is a mucin encoded by the MUC1 gene in humans. Mucin short variant S1 is a glycoprotein with extensive O-linked glycosylation of its extracellular domain. Mucins line the apical surface of epithelial cells in the lungs, stomach, intestines, eyes and several other organs. Mucins protect the body from infection by pathogen binding to oligosaccharides in the extracellular domain, preventing the pathogen from reaching the cell surface. Overexpression of MUC1 is often associated with colon, breast, ovarian, lung and pancreatic cancers. Joyce Taylor-Papadimitriou identified and characterised the antigen during her work with breast and ovarian tumors.
Chemoimmunotherapy is chemotherapy combined with immunotherapy. Chemotherapy uses different drugs to kill or slow the growth of cancer cells; immunotherapy uses treatments to stimulate or restore the ability of the immune system to fight cancer. A common chemoimmunotherapy regimen is CHOP combined with rituximab (CHOP-R) for B-cell non-Hodgkin lymphomas.
Glypican-3 is a protein that, in humans, is encoded by the GPC3 gene. The GPC3 gene is located on human X chromosome (Xq26) where the most common gene encodes a 70-kDa core protein with 580 amino acids. Three variants have been detected that encode alternatively spliced forms termed Isoforms 1 (NP_001158089), Isoform 3 (NP_001158090) and Isoform 4 (NP_001158091).
Transmembrane 4 L6 family member 1 is a protein that in humans is encoded by the TM4SF1 gene.
A circulating tumor cell (CTC) is a cancer cell from a primary tumor that has shed into the blood of the circulatory system, or the lymph of the lymphatic system. CTCs are carried around the body to other organs where they may leave the circulation and become the seeds for the subsequent growth of secondary tumors. This is known as metastasis, responsible for most cancer-related deaths.
Monomethyl auristatin E (MMAE) is a synthetic antineoplastic agent. Because of its toxicity, it cannot be used as a drug itself; instead, it is linked to a monoclonal antibody (MAB) which directs it to the cancer cells. In International Nonproprietary Names for MMAE-MAB-conjugates, the name vedotin refers to MMAE plus its linking structure to the antibody. It is a potent antimitotic drug derived from peptides occurring in marine shell-less mollusc Dolabella auricularia called dolastatins which show potent activity in preclinical studies, both in vitro and in vivo, against a range of lymphomas, leukemia and solid tumors. These drugs show potency of up to 200 times that of vinblastine, another antimitotic drug used for Hodgkin lymphoma as well as other types of cancer.
A trifunctional antibody is a monoclonal antibody with binding sites for two different antigens, typically CD3 and a tumor antigen, making it a type of bispecific monoclonal antibody. In addition, its intact Fc-part can bind to an Fc receptor on accessory cells like conventional monospecific antibodies. The net effect is that this type of drug links T cells and monocytes/macrophages, natural killer cells, dendritic cells or other Fc receptor expressing cells to the tumor cells, leading to their destruction.
Antibody–drug conjugates or ADCs are a class of biopharmaceutical drugs designed as a targeted therapy for treating cancer. Unlike chemotherapy, ADCs are intended to target and kill tumor cells while sparing healthy cells. As of 2019, some 56 pharmaceutical companies were developing ADCs.
Cytokine-induced killer cells (CIK) cells are a group of immune effector cells featuring a mixed T- and natural killer (NK) cell-like phenotype. They are generated by ex vivo incubation of human peripheral blood mononuclear cells (PBMC) or cord blood mononuclear cells with interferon-gamma (IFN-γ), anti-CD3 antibody, recombinant human interleukin (IL)-1 and recombinant human interleukin (IL)-2.
Patritumab deruxtecan is an experimental antibody–drug conjugate developed by Merck and Daiichi Sankyo to treat non-small-cell lung cancer.
Immunoliposome therapy is a targeted drug delivery method that involves the use of liposomes coupled with monoclonal antibodies to deliver therapeutic agents to specific sites or tissues in the body. The antibody modified liposomes target tissue through cell-specific antibodies with the release of drugs contained within the assimilated liposomes. Immunoliposome aims to improve drug stability, personalize treatments, and increased drug efficacy. This form of therapy has been used to target specific cells, protecting the encapsulated drugs from degradation in order to enhance their stability, to facilitate sustained drug release and hence to advance current traditional cancer treatment.
Deruxtecan is a chemical compound and a derivative of exatecan that acts as topoisomerase I inhibitor.
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