Monoclonal antibody | |
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Type | Whole antibody |
Source | Human |
Target | Epidermal growth factor receptor |
Clinical data | |
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Chemical and physical data | |
Formula | C6512H10074N1734O2032S46 |
Molar mass | 146643.09 g·mol−1 |
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Zalutumumab (proposed trade name HuMax-EGFR) is a fully human IgG1 monoclonal antibody (mAb) directed towards the epidermal growth factor receptor (EGFR). It is a product developed by Genmab in Utrecht, the Netherlands. Specifically, zalutumumab is designed for the treatment of squamous cell carcinoma of the head and neck (SCCHN), a type of cancer.
Zalutumumab works through inhibition of the EGFR signal. The EGFR is a receptor tyrosine kinase. Its structure includes an extracellular binding domain, a transmembrane lipophilic segment, and an intracellular tyrosine kinase domain.
EGFR is over-expressed by many tumor cells. Upon binding by a ligand, such as the epidermal growth factor or TGF alpha, dimerization occurs, leading to autophosphorylation on the intracellular tyrosine residues. Following phosphorylation, the Grb2-SOS signaling complex is stimulated. This causes the activation of the G protein RAS through the exchange of guanosine diphosphate (GDP) for guanosine triphosphate (GTP). The exchange of GDP for GTP induces a conformational change of RAS to allow it to bind to Raf-1. Raf-1 is then activated through another multistep mechanism in which dephosphorylation of inhibitory sites by protein phosphatase 2A (PP2A), as well as the phosphorylation of activating sites by p21 activated kinase (PAK) occurs. After this, Raf-1 activates MAPK/ERK kinase (MEK), which then goes on to activate extracellular-signal-regulated kinase (ERK). ERK is then able to enter the cell nucleus and control gene expression by phosphorylating various transcription factors, such as Elk-1. It is from there that the specific gene transcription occurs to initiate the cell cycle. Through this mechanism, apoptosis is inhibited, angiogenesis, migration, adhesion, and invasion occur. Each of these is a functional element to the progression and development of cancer, which is defined as an abnormal growth of cells with a tendency to proliferate in an uncontrolled way and, in some cases, to metastasize. [1]
In order to combat SCCHN, zalutumumab was designed to inhibit the EGFR signaling. Specifically, it binds to the EGFR Domain III on the cell surface. This locks the receptor in an inactive conformation, making the drug an inverse agonist. In doing this it is also acting as a competitive antagonist for the EGF ligand. In the inactive conformation, the distance between the intracellular tyrosine kinase residues is larger, which inhibits dimerization. Phosphorylation is consequently inhibited, so that no signal is released. Without a signal, cell cycle characteristics to enhance tumor growth are inhibited and the cancer progression is suppressed. [2]
This is not the only way in which zalutumumab works. It also is responsible for some antitumor affects through antibody-dependent cellular cytotoxicity (ADCC). The Fab, or fragment antigen binding region of the antibody, binds to the antigen on the EGFr expressing tumor cells. Through an immunological response, the body’s natural killer (NK) cells, which are a type of lymphocyte, recognize and bind to the Fc portion on the antibody through an Fc receptor, CD16. The NK cell is then activated through the cross linking of the Fc receptors which sends a signal to induce apoptosis and cell death. The target tumor cell is then destroyed. [2]
2009: Zalutumumab treatment was approved for Fast Track status by the U.S. Food and Drug Administration for patients suffering from SCCHN who have failed standard therapies and have no other options. The drug has undergone pre-clinical and Phase I and II studies and is also in Phases I and II for SCCHN front-line with chemo-radiation and SCCHN with radiation. Additionally, a Phase II is under way for SCCHN and Phase III studies are also being performed for SCCHN and SCCHN front-line with radio therapy. [3]
2010:A phase III study (of zalutumumab as an addition to 'best supportive care' in patients after failed standard platinum-based chemotherapy) reported a non-significant improvement in overall survival, and a significant 61% improvement in Progression-free survival [4]
2014:A study of zalutumumab as addition to chemoradiation for SCCHN showed no benefit, [5] and 94% developed a skin rash (11% severe enough to discontinue).
2015:Genmab not proceeding with zalutumumab. [6]
A protein kinase is a kinase which selectively modifies other proteins by covalently adding phosphates to them (phosphorylation) as opposed to kinases which modify lipids, carbohydrates, or other molecules. Phosphorylation usually results in a functional change of the target protein (substrate) by changing enzyme activity, cellular location, or association with other proteins. The human genome contains about 500 protein kinase genes and they constitute about 2% of all human genes. There are two main types of protein kinase. The great majority are serine/threonine kinases, which phosphorylate the hydroxyl groups of serines and threonines in their targets. Most of the others are tyrosine kinases, although additional types exist. Protein kinases are also found in bacteria and plants. Up to 30% of all human proteins may be modified by kinase activity, and kinases are known to regulate the majority of cellular pathways, especially those involved in signal transduction.
A tyrosine kinase is an enzyme that can transfer a phosphate group from ATP to the tyrosine residues of specific proteins inside a cell. It functions as an "on" or "off" switch in many cellular functions.
Autocrine signaling is a form of cell signaling in which a cell secretes a hormone or chemical messenger that binds to autocrine receptors on that same cell, leading to changes in the cell. This can be contrasted with paracrine signaling, intracrine signaling, or classical endocrine signaling.
Gefitinib, sold under the brand name Iressa, is a medication used for certain breast, lung and other cancers. Gefitinib is an EGFR inhibitor, like erlotinib, which interrupts signaling through the epidermal growth factor receptor (EGFR) in target cells. Therefore, it is only effective in cancers with mutated and overactive EGFR, but resistances to gefitinib can arise through other mutations. It is marketed by AstraZeneca and Teva.
The epidermal growth factor receptor is a transmembrane protein that is a receptor for members of the epidermal growth factor family of extracellular protein ligands.
Hepatocyte growth factor receptor is a protein that in humans is encoded by the MET gene. The protein possesses tyrosine kinase activity. The primary single chain precursor protein is post-translationally cleaved to produce the alpha and beta subunits, which are disulfide linked to form the mature receptor.
Biological crosstalk refers to instances in which one or more components of one signal transduction pathway affects another. This can be achieved through a number of ways with the most common form being crosstalk between proteins of signaling cascades. In these signal transduction pathways, there are often shared components that can interact with either pathway. A more complex instance of crosstalk can be observed with transmembrane crosstalk between the extracellular matrix (ECM) and the cytoskeleton.
The MAPK/ERK pathway is a chain of proteins in the cell that communicates a signal from a receptor on the surface of the cell to the DNA in the nucleus of the cell.
Receptor tyrosine kinases (RTKs) are the high-affinity cell surface receptors for many polypeptide growth factors, cytokines, and hormones. Of the 90 unique tyrosine kinase genes identified in the human genome, 58 encode receptor tyrosine kinase proteins. Receptor tyrosine kinases have been shown not only to be key regulators of normal cellular processes but also to have a critical role in the development and progression of many types of cancer. Mutations in receptor tyrosine kinases lead to activation of a series of signalling cascades which have numerous effects on protein expression. The receptors are generally activated by dimerization and substrate presentation. Receptor tyrosine kinases are part of the larger family of protein tyrosine kinases, encompassing the receptor tyrosine kinase proteins which contain a transmembrane domain, as well as the non-receptor tyrosine kinases which do not possess transmembrane domains.
Matuzumab is a humanized monoclonal antibody for the treatment of cancer. It binds to the epidermal growth factor receptor (EGFR) with high affinity. The mouse monoclonal antibody (mAb425) from which matuzumab was developed at the Wistar Institute in Philadelphia, Pennsylvania
Fibroblast growth factor receptor 1 (FGFR1), also known as basic fibroblast growth factor receptor 1, fms-related tyrosine kinase-2 / Pfeiffer syndrome, and CD331, is a receptor tyrosine kinase whose ligands are specific members of the fibroblast growth factor family. FGFR1 has been shown to be associated with Pfeiffer syndrome, and clonal eosinophilias.
The ErbB family of proteins contains four receptor tyrosine kinases, structurally related to the epidermal growth factor receptor (EGFR), its first discovered member. In humans, the family includes Her1, Her2 (ErbB2), Her3 (ErbB3), and Her4 (ErbB4). The gene symbol, ErbB, is derived from the name of a viral oncogene to which these receptors are homologous: erythroblastic leukemia viral oncogene. Insufficient ErbB signaling in humans is associated with the development of neurodegenerative diseases, such as multiple sclerosis and Alzheimer's disease, while excessive ErbB signaling is associated with the development of a wide variety of types of solid tumor.
SHC-transforming protein 1 is a protein that in humans is encoded by the SHC1 gene. SHC has been found to be important in the regulation of apoptosis and drug resistance in mammalian cells.
Receptor tyrosine-protein kinase erbB-3, also known as HER3, is a membrane bound protein that in humans is encoded by the ERBB3 gene.
Proto-oncogene tyrosine-protein kinase Src, also known as proto-oncogene c-Src, or simply c-Src, is a non-receptor tyrosine kinase protein that in humans is encoded by the SRC gene. It belongs to a family of Src family kinases and is similar to the v-Src gene of Rous sarcoma virus. It includes an SH2 domain, an SH3 domain and a tyrosine kinase domain. Two transcript variants encoding the same protein have been found for this gene.
Cell surface receptors are receptors that are embedded in the plasma membrane of cells. They act in cell signaling by receiving extracellular molecules. They are specialized integral membrane proteins that allow communication between the cell and the extracellular space. The extracellular molecules may be hormones, neurotransmitters, cytokines, growth factors, cell adhesion molecules, or nutrients; they react with the receptor to induce changes in the metabolism and activity of a cell. In the process of signal transduction, ligand binding affects a cascading chemical change through the cell membrane.
A tyrosine kinase inhibitor (TKI) is a pharmaceutical drug that inhibits tyrosine kinases. Tyrosine kinases are enzymes responsible for the activation of many proteins by signal transduction cascades. The proteins are activated by adding a phosphate group to the protein (phosphorylation), a step that TKIs inhibit. TKIs are typically used as anticancer drugs. For example, they have substantially improved outcomes in chronic myelogenous leukemia. They have also been used to treat other diseases, such as idiopathic pulmonary fibrosis.
AEE788 is a multitargeted human epidermal receptor (HER) 1/2 and vascular endothelial growth factor receptor (VEGFR) 1/2 receptor family tyrosine kinases inhibitor with IC50 of 2, 6, 77, 59 nM for EGFR, ErbB2, KDR, and Flt-1. In cells, growth factor-induced EGFR and ErbB2 phosphorylation was also efficiently inhibited with IC50s of 11 and 220 nM, respectively. It efficiently inhibited growth factor-induced EGFR and ErbB2 phosphorylation in tumors for >72 h, a phenomenon correlating with the antitumor efficacy of intermittent treatment schedules. It also inhibits VEGF-induced angiogenesis in a murine implant model. It has potential as an anticancer agent targeting deregulated tumor cell proliferation as well as angiogenic parameters.
Autophosphorylation is a type of post-translational modification of proteins. It is generally defined as the phosphorylation of the kinase by itself. In eukaryotes, this process occurs by the addition of a phosphate group to serine, threonine or tyrosine residues within protein kinases, normally to regulate the catalytic activity. Autophosphorylation may occur when a kinases' own active site catalyzes the phosphorylation reaction, or when another kinase of the same type provides the active site that carries out the chemistry. The latter often occurs when kinase molecules dimerize. In general, the phosphate groups introduced are gamma phosphates from nucleoside triphosphates, most commonly ATP.
VEGFR-2 inhibitor, also known as kinase insert domain receptor(KDR) inhibitor, are tyrosine kinase receptor inhibitors that reduce angiogenesis or lymphangiogenesis, leading to anticancer activity. Generally they are small, synthesised molecules that bind competitively to the ATP-site of the tyrosine kinase domain. VEGFR-2 selective inhibitor can interrupt multiple signaling pathways involved in tumor, including proliferation, metastasis and angiogenesis.