Carcinoembryonic antigen | |
---|---|
Identifiers | |
Symbol | CEACAM |
Membranome | 211 |
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 (about 2–4 ng/mL). [2] 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. [3]
CEA are glycosyl phosphatidyl inositol (GPI) cell-surface-anchored glycoproteins whose specialized sialo fucosylated glycoforms serve as functional colon carcinoma L-selectin and E-selectin ligands, which may be critical to the metastatic dissemination of colon carcinoma cells. [4] [5] [6] Immunologically they are characterized as members of the CD66 cluster of differentiation. The proteins include CD66a, CD66b, CD66c, CD66d, CD66e, CD66f.
CEA was first identified in 1965 by Phil Gold, a Canadian physician, scientist and professor and Samuel O. Freedman who is also a Canadian professor of immunology in human colon cancer tissue extracts. [7]
The CEA blood test is not reliable for diagnosing cancer or as a screening test for early detection of cancer. [8] Most types of cancer do not result in a high CEA level. [9]
Serum from individuals with colorectal carcinoma often has higher levels of CEA than healthy individuals (above approximately 2.5ng/mL). [10] CEA measurement is mainly used as a tumor marker to monitor colorectal carcinoma treatment, to identify recurrences after surgical resection, for staging or to localize cancer spread through measurement of biological fluids. [11] CEA levels may also be raised in gastric carcinoma, pancreatic carcinoma, lung carcinoma, breast carcinoma, and medullary thyroid carcinoma, as well as some non-neoplastic conditions like ulcerative colitis, pancreatitis, cirrhosis, [12] COPD, Crohn's disease, hypothyroidism [13] as well as in smokers. [14] Elevated CEA levels should return to normal after successful surgical removal of the tumor and can be used in follow up, especially of colorectal cancers. [15]
CEA elevation is known to be affected by multiple factors. It varies inversely with tumor grade; well-differentiated tumors secrete more CEA. CEA is elevated more in tumors with lymph node and distant metastasis than in organ-confined tumors and, thus, varies directly with tumor stage. Left-sided tumors generally tend to have higher CEA levels than right-sided tumors. [16] Tumors causing bowel obstruction produce higher CEA levels. [16] Aneuploid tumors produce more CEA than diploid tumors. [17] Liver dysfunction increases CEA levels as the liver is the primary site of CEA metabolism. [3]
An anti-CEA antibody is an antibody against CEA. Such antibodies to CEA are commonly used in immunohistochemistry to identify cells expressing the glycoprotein in tissue samples. In adults, CEA is primarily expressed in cells of tumors (some malignant, some benign) [19] but they are particularly associated with the adenocarcinomas, such as those arising in the colon, lung, breast, stomach, or pancreas. It can therefore be used to distinguish between these and other similar cancers. For example, it can help to distinguish between adenocarcinoma of the lung and mesothelioma, a different type of lung cancer which is not normally CEA positive. Because even monoclonal antibodies to CEA tend to have some degree of cross-reactivity, occasionally giving false positive results, it is commonly employed in combination with other immunohistochemistry tests, such as those for BerEp4, WT1, and calretinin. [20] For cancers that highly express CEA, targeting CEA through radioimmunotherapy is one of the therapy approaches. [21] Engineered antibodies such as single-chain Fv antibodies (sFvs) or bispecific antibodies have been used for targeting and therapy of CEA expressing tumors both in vitro and in vivo with promising results [22] [23] Regions of high CEA levels in the body can be detected with the monoclonal antibody arcitumomab. [24]
CEA and related genes make up the CEA family belonging to the immunoglobulin superfamily.
In humans, the carcinoembryonic antigen family consists of 29 genes, 18 of which are normally expressed. [25] The following is a list of human genes which encode carcinoembryonic antigen-related cell adhesion proteins: CEACAM1, CEACAM3, CEACAM4, CEACAM5, CEACAM6, CEACAM7, CEACAM8, CEACAM16, CEACAM18, CEACAM19, CEACAM20, CEACAM21
CEA is expressed in many different types of cancer like lung, gastric , pancreatic and colorectal cancer. Many clinical trials have been performed .
CEA is used as tumor biomarker that can be used for Targeted Radionuclide Therapy. The cT84.66 is a chimeric antibody of murine origin that has been tested in phase I clinical trials with 111-In and 90-Yttrium. [26] [27] 111-In and 90-Y are β- emitters that are used in clinics for imaging and therapy respectively. The results were promising but a number of patients demostrated immune responses and they had to withdraw from participating in the clinical trial. [28] The cT84.66 antibody was huminized and in 2020, a phase I clinical trial was performed during which 18 cancer patients received an injection of 90Y-DOTA-M5A. [29] The results of this trial demonstrated a stable disease for 10/18 patients ( 56%) and had no immunogenic response.
M5A-DOTA was coupled with 225-Ac , which is an alpa emitter, and an in vivo study was performed where cytokine therapy was combined with a-therapy. [30] The result of the study revealed the benefit of combining these two treamtents. Based on the results of this study, an ongoing clinical phase I study is currently underway (NCT05204147). The goal of this study is to establish the safety level and THE possible benefit of administrating M5A-DOTA-225-Ac.
Keratin 20, often abbreviated CK20, is a protein that in humans is encoded by the KRT20 gene.
A tumor marker is a biomarker that can be used to indicate the presence of cancer or the behavior of cancers. They can be found in bodily fluids or tissue. Markers can help with assessing prognosis, surveilling patients after surgical removal of tumors, and even predicting drug-response and monitor therapy.
The CD44 antigen is a cell-surface glycoprotein involved in cell–cell interactions, cell adhesion and migration. In humans, the CD44 antigen is encoded by the CD44 gene on chromosome 11. CD44 has been referred to as HCAM, Pgp-1, Hermes antigen, lymphocyte homing receptor, ECM-III, and HUTCH-1.
Radioimmunotherapy (RIT) uses an antibody labeled with a radionuclide to deliver cytotoxic radiation to a target cell. It is a form of unsealed source radiotherapy. In cancer therapy, an antibody with specificity for a tumor-associated antigen is used to deliver a lethal dose of radiation to the tumor cells. The ability for the antibody to specifically bind to a tumor-associated antigen increases the dose delivered to the tumor cells while decreasing the dose to normal tissues. By its nature, RIT requires a tumor cell to express an antigen that is unique to the neoplasm or is not accessible in normal cells.
Tumor M2-PK is a synonym for the dimeric form of the pyruvate kinase isoenzyme type M2 (PKM2), a key enzyme within tumor metabolism. Tumor M2-PK can be elevated in many tumor types, rather than being an organ-specific tumor marker such as PSA. Increased stool (fecal) levels are being investigated as a method of screening for colorectal tumors, and EDTA plasma levels are undergoing testing for possible application in the follow-up of various cancers.
TroVax is a cancer vaccine that was developed by Oxford BioMedica. No cancer vaccines have been proven to cure cancer or extend life yet, TroVax has been studied in a number of trials for colon cancer.
Technetium (99mTc) arcitumomab was a drug used for the diagnostic imaging of colorectal cancers, marketed by Immunomedics. It consisted of the Fab' fragment of a monoclonal antibody and a radionuclide, technetium-99m.
Carbohydrate antigen 19-9 (CA19-9), also known as sialyl-LewisA, is a tetrasaccharide which is usually attached to O-glycans on the surface of cells. It is known to play a role in cell-to-cell recognition processes. It is also a tumor marker used primarily in the management of pancreatic cancer.
Mesothelin, also known as MSLN, is a protein that in humans is encoded by the MSLN gene.
An oncoantigen is a surface or soluble tumor antigen that supports tumor growth. A major problem of cancer immunotherapy is the selection of tumor cell variants that escape immune recognition. The notion of oncoantigen was set forth in the context of cancer immunoprevention to define a class of persistent tumor antigens not prone to escape from immune recognition.
Medullary thyroid cancer is a form of thyroid carcinoma which originates from the parafollicular cells, which produce the hormone calcitonin. Medullary tumors are the third most common of all thyroid cancers and together make up about 3% of all thyroid cancer cases. MTC was first characterized in 1959.
Tumor-associated glycoprotein 72 (TAG-72) is a glycoprotein found on the surface of many cancer cells, including ovary, breast, colon, lung, and pancreatic cancers. It is a mucin-like molecule with a molar mass of over 1000 kDa.
Galectin-4 is a protein that in humans is encoded by the LGALS4 gene.
Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) also known as CD66e, is a member of the carcinoembryonic antigen (CEA) gene family.
James L. Gulley is an American cancer researcher and the Director of the Medical Oncology Service at National Cancer Institute.
Adoptive cell transfer (ACT) is the transfer of cells into a patient. The cells may have originated from the patient or from another individual. The cells are most commonly derived from the immune system with the goal of improving immune functionality and characteristics. In autologous cancer immunotherapy, T cells are extracted from the patient, genetically modified and cultured in vitro and returned to the same patient. Comparatively, allogeneic therapies involve cells isolated and expanded from a donor separate from the patient receiving the cells.
Pelareorep is a proprietary isolate of the unmodified human reovirus being developed as a systemically administered immuno-oncological viral agent for the treatment of solid tumors and hematological malignancies. Pelareorep is an oncolytic virus, which means that it preferentially lyses cancer cells. Pelareorep also promotes an inflamed tumor phenotype through innate and adaptive immune responses. Preliminary clinical trials indicate that it may have anti-cancer effects across a variety of cancer types when administered alone and in combination with other cancer therapies.
Neuvenge, Lapuleucel-T, is a therapeutic cancer vaccine (TCV) in development by Dendreon (DNDN). It uses the "immunotherapy platform approach" first successfully demonstrated on the U.S. Food and Drug Administration (FDA)-approved TCV Provenge. It was first tested on breast cancer patients with tumors expressing HER2/neu, and is now scheduled to be tested on bladder cancer patients.
A cancer biomarker refers to a substance or process that is indicative of the presence of cancer in the body. A biomarker may be a molecule secreted by a tumor or a specific response of the body to the presence of cancer. Genetic, epigenetic, proteomic, glycomic, and imaging biomarkers can be used for cancer diagnosis, prognosis, and epidemiology. Ideally, such biomarkers can be assayed in non-invasively collected biofluids like blood or serum.
hPG80 refers to the extracellular and oncogenic version of progastrin. This name first appeared in a scientific publication in January 2020. Until that date, scientific publications only mention 'progastrin', without necessarily explicitly specifying whether it is intracellular or extracellular in the tumor pathological setting.
{{cite journal}}
: CS1 maint: multiple names: authors list (link)