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alpha-Amanitin or α-amanitin is a cyclic peptide of eight amino acids. It is possibly the most deadly of all the amatoxins, toxins found in several species of the mushroom genus Amanita, one being the death cap as well as the destroying angel, a complex of similar species, principally A. virosa and A. bisporigera. It is also found in the mushrooms Galerina marginata and Conocybe filaris. The oral LD50 of amanitin is approximately 0.1 mg/kg for rats.
Monoclonal antibodies are antibodies that are made by identical immune cells that are all clones of a unique parent cell. Monoclonal antibodies can have monovalent affinity, in that they bind to the same epitope. In contrast, polyclonal antibodies bind to multiple epitopes and are usually made by several different plasma cell lineages. Bispecific monoclonal antibodies can also be engineered, by increasing the therapeutic targets of one single monoclonal antibody to two epitopes.
Immunohistochemistry (IHC) is the most common application of immunostaining. It involves the process of selectively identifying antigens (proteins) in cells of a tissue section by exploiting the principle of antibodies binding specifically to antigens in biological tissues. IHC takes its name from the roots "immuno", in reference to antibodies used in the procedure, and "histo", meaning tissue. Albert Coons conceptualized and first implemented the procedure in 1941.
An immunotoxin is an artificial protein consisting of a targeting portion linked to a toxin. When the protein binds to that cell, it is taken in through endocytosis, and the toxin kills the cell. They are used for the treatment of some kinds of cancer and a few viral infections.
Cancer immunotherapy is the artificial stimulation of the immune system to treat cancer, improving on the immune system's natural ability to fight the disease. It is an application of the fundamental research of cancer immunology and a growing subspeciality of oncology. It exploits the fact that cancer cells often have tumor antigens, molecules on their surface that can be detected by the antibody proteins of the immune system, binding to them. The tumor antigens are often proteins or other macromolecules. Normal antibodies bind to external pathogens, but the modified immunotherapy antibodies bind to the tumor antigens marking and identifying the cancer cells for the immune system to inhibit or kill. In 2018, James P. Allison and Tasuku Honjo received the Nobel Prize in Physiology or Medicine for their discovery of cancer therapy by inhibition of negative immune regulation.
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.
The nomenclature of monoclonal antibodies is a naming scheme for assigning generic, or nonproprietary, names to monoclonal antibodies. An antibody is a protein that is produced in B cells and used by the immune system of humans and other vertebrate animals to identify a specific foreign object like a bacterium or a virus. Monoclonal antibodies are those that were produced in identical cells, often artificially, and so share the same target object. They have a wide range of applications including medical uses.
Monoclonal antibody therapy is a form of immunotherapy that uses monoclonal antibodies (mAb) to bind monospecifically to certain cells or proteins. The objective is that this treatment will stimulate the patient's immune system to attack those cells. Alternatively, in radioimmunotherapy a radioactive dose localizes a target cell line, delivering lethal chemical doses. More recently antibodies have been used to bind to molecules involved in T-cell regulation to remove inhibitory pathways that block T-cell responses. This is known as immune checkpoint therapy.
Inotuzumab ozogamicin is an antibody-drug conjugate used to treat relapsed or refractory B-cell precursor acute lymphoblastic leukemia (ALL).
Anti-Müllerian hormone receptor is a receptor for anti-Müllerian hormone.
Affibody molecules are small, robust proteins engineered to bind to a large number of target proteins or peptides with high affinity, imitating monoclonal antibodies, and are therefore a member of the family of antibody mimetics. Affibody molecules are used in biochemical research and are being developed as potential new biopharmaceutical drugs. These molecules can be used for molecular recognition in diagnostic and therapeutic applications.
Folate targeting is a method utilized in biotechnology for drug delivery purposes. This Trojan Horse process, which was created by Drs. Christopher P. Leamon and Philip S. Low, involves the attachment of the vitamin, folate, to a molecule/drug to form a "folate conjugate". Based on the natural high affinity of folate for the folate receptor protein (FR), which is commonly expressed on the surface of many human cancers, folate-drug conjugates also bind tightly to the FR and trigger cellular uptake via endocytosis. Molecules as diverse as small radiodiagnostic imaging agents to large DNA plasmid formulations have successfully been delivered inside FR-positive cells and tissues.
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.
A maytansinoid is a chemical derivative of maytansine.
Trastuzumab emtansine also known as ado-trastuzumab emtansine and sold under the trade name Kadcyla, is an antibody-drug conjugate consisting of the humanized monoclonal antibody trastuzumab (Herceptin) covalently linked to the cytotoxic agent DM1. Trastuzumab alone stops growth of cancer cells by binding to the HER2 receptor, whereas trastuzumab emtansine undergoes receptor-mediated internalization into cells, is catabolized in lysosomes where DM1-containing catabolites are released and subsequently bind tubulin to cause mitotic arrest and cell death. Trastuzumab binding to HER2 prevents homodimerization or heterodimerization (HER2/HER3) of the receptor, ultimately inhibiting the activation of MAPK and PI3K/AKT cellular signalling pathways. Because the monoclonal antibody targets HER2, and HER2 is only over-expressed in cancer cells, the conjugate delivers the cytotoxic agent DM1 specifically to tumor cells. The conjugate is abbreviated T-DM1.
Photoimmunotherapy (PIT) is an oncological treatment that combines photodynamic therapy of tumor with immunotherapy treatment. Combining photodynamic therapy with immunotherapy enhances the immunostimulating response and has synergistic effects for metastatic cancer treatment.
Directed enzyme prodrug therapy (DEPT) uses enzymes artificially introduced into the body to convert prodrugs, which have no or poor biologically activity, to the active form in the desired location within the body. Many chemotherapy drugs for cancer lack tumour specificity and the doses required to reach therapeutic levels in the tumour are often toxic to other tissues. DEPT strategies are an experimental method of reducing the systemic toxicity of a drug, by achieving high levels of the active drug only at the desired site. This article describes the variations of DEPT technology.
cBR96-doxorubicin immunoconjugate is an antibody-drug conjugate or (ADC) directed to the Lewis-Y antigen designed for the treatment of cancer. The payload is the chemotherapy drug doxorubicin which is connected with a hydrazone linker to cysteine residues of the Lewis-Y specific (chimeric) monoclonal antibody BR96. Following internalization, the hydrazone is hydrolyzed within the acidic environment of target cell endosomes and lysosomes to release active cytotoxic drug.
Enfortumab vedotin (ASG-22ME) is an antibody-drug conjugate designed for the treatment of cancer expressing Nectin-4. Enfortumab refers to the monoclonal antibody part, and vedotin refers to the payload drug (MMAE) and the linker.
CRM197 is a non-toxic mutant of diphtheria toxin, currently used as a carrier protein for polysaccharides and haptens to make them immunogenic. There is some dispute about the toxicity of CRM197, with evidence that it is toxic to yeast cells and some mammalian cell lines.
References
- ↑ Goldenberg DM, Sharkey RM (2007). "Novel radiolabeled antibody conjugates". Oncogene. 26 (25): 3734–44. doi:10.1038/sj.onc.1210373. PMID 17530026.
- ↑ Khandare JJ, Minko T (2006). "Antibodies and peptides in cancer therapy". Critical Reviews in Therapeutic Drug Carrier Systems. 23 (5): 401–35. doi:10.1615/CritRevTherDrugCarrierSyst.v23.i5.20. PMID 17425513.
