Two chemically linked fragments antigen-binding form an artificial

antibody An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

that binds to two different antigens, making it a type of

bispecific antibody A bispecific monoclonal antibody (BsMAb, BsAb) is an artificial protein that can simultaneously bind to two different types of antigen or two different epitopes on the same antigen. Naturally occurring antibodies typically only target one antigen. ...

. They are fragments antigen-binding (Fab or Fab') of two different monoclonal antibodies and are linked by chemical means like a

thioether In organic chemistry, an organic sulfide (British English sulphide) or thioether is an organosulfur functional group with the connectivity as shown on right. Like many other sulfur-containing compounds, volatile sulfides have foul odors. A su ...

. Typically, one of the Fabs binds to a

tumour antigen Tumor antigen is an antigenic substance produced in tumor cells, i.e., it triggers an immune response in the host. Tumor antigens are useful tumor markers in identifying tumor cells with diagnostic tests and are potential candidates for use in ...

(such as

CD30 CD30, also known as TNFRSF8 ( TNF receptor superfamily member 8), is a cell membrane protein of the tumor necrosis factor receptor family and a tumor marker. Function This receptor is expressed by activated, but not by resting, T and B cel ...

) and the other to a protein on the surface of an

immune cell White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from multi ...

, for example an Fc receptor on a macrophage. In this way, tumour cells are attached to immune cells, which destroy them. In the late 1990s and early 2000s,

clinical trial Clinical trials are prospective biomedical or behavioral research studies on human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, diet ...

s with chemically linked Fabs were conducted for the treatment of various types of

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

. Early results were promising, but the concept was dropped because of high production costs.

Bi-specific T-cell engager Bi-specific T-cell engagers (BiTEs) are a class of artificial bispecific monoclonal antibodies that are investigated for use as anti-cancer drugs. They direct a host's immune system, more specifically the T cells' cytotoxic activity, against cance ...

s employ a similar mechanism of action while being cheaper.

References

Monoclonal antibodies Antineoplastic drugs {{antineoplastic-drug-stub