Radioimmunotherapy
The radioimmunotherapy is a novel method of cancer therapy . It combines the effectiveness of radiation therapy with the selectivity of immunotherapeutic agents ( radionuclide therapy ). In radioimmunotherapy, conjugated radiopharmaceuticals are used, which consist of an antibody and a radioisotope and thus represent a form of drug targeting .
Unlike chemotherapy , which unspecifically damages all cells that are dividing - e.g. B. also the formation cells of the hair or the mucous membrane cells of the mouth, stomach and intestines - the radioimmunotherapy works largely selectively against a selected, specific cell type.
To do this, it is necessary to find a surface structure that only occurs on this type of cell. A monoclonal antibody must then be produced for precisely this structure . For low-grade non-Hodgkin lymphoma , a form of lymph gland cancer in which a B cell has degenerated, this has been achieved with the CD20 structure. A radioisotope is now coupled to this monoclonal antibody . This is done with the help of a chemical intermediate molecule that connects both components.
In this way, a form of therapy has been created which, due to the antibody, specifically and selectively detects the desired cell type everywhere in the body and at the same time is able to irradiate these cells inside the body directly at the target location. As a result, the tumor cells receive a high dose of radiation , but surrounding, healthy tissue is largely spared.
Due to the so-called crossfire effect, tumor cells that are difficult to access for the antibody, such as e.g. B. Lymphoma cell accumulations in the lymph nodes , captured and destroyed by radiation. Due to the close proximity of the radiation source to the target cells, a lower radiation intensity is required compared to external radiation therapy , which leads to a much better tolerance.
Examples
Ibritumomab tiuxetan is different in the radio immunotherapy of malignant B-cell - lymphoma applied (lymphoma). It is a conjugate of a monoclonal antibody directed against the CD20 B-lymphocyte antigen is directed at the surface of, and the chelator tiuxetan (a DTPA - derivative ), for example, the radioactive isotope yttrium can complex -90.
Tositumomab , a murine monoclonal antibody labeled with 131 iodine , is approved for the treatment of non-Hodgkin lymphomas .
Web links
Individual evidence
- ↑ RM Sharkey and DM Goldenberg: Perspectives on cancer therapy with radiolabeled monoclonal antibodies. In: J Nucl Med 46, 2005, pp. 115S-127S. PMID 15653660 (Review).