Antibodies and the Immune System
The immune system is a network of specialized cells that defend the body against "foreign" invaders (antigens) including bacteria, viruses, and parasites. An important part of the immune system are proteins called antibodies. The immune system makes antibodies to attach to the antigens which are usually found on the surface of cells. The antigens can then be identified and destroyed by antibodies or other cells in the immune system. Antibodies hold promise in the treatment of cancer.
Monoclonal Antibodies
Monoclonal antibodies (MABs or MOABs) work on cancer cells in the same way natural antibodies work, by identifying and binding to the target cells. They then alert other cells in the immune system to the presence of the cancer cells. MABs are specific for a particular antigen - one designed for a B-cell lymphoma will not work on cells for ovarian cancer cells for example.
MABs are classified as Biological Response Modifiers. Since they affect the immune system they are called immunotherapy as opposed to chemotherapy which are drugs which tend to interfere in cancer cell growth.
Researchers make MABs by injecting human cancer cells into mice so that their immune systems will make antibodies against these cancer cells. Researchers remove the mouse cells that are producing these antibodies and fuse them with a laboratory grown immortal cell to create a "hybrid" cell called a hybridoma. Hybridomas are like factories that can indefinitely produce large quantities of these pure monoclonal antibodies.
MABs by themselves may enhance a patient's immune response to the cancer. Some antitumor effects have been seen in the antibody treatment of lymphoma and some other cancers. But this treatment is not perfect. Sometimes the injected antibodies produce no response or block a normal response. Cancer cells can also hide their antigens, making themselves less likely to be destroyed. A way to increase the effectiveness of MABs is to combine them with another form of therapy.
For example, MABs can be bound to a chemotherapy agent. Through this combination, two mechanisms attack the cell: the chemical from the chemotherapy and the immune response from the MAB. Chemotherapy can be more effective when the cells are weakened by the MAB.
Radiation can also be combined with MAB. In this case, the monoclonal antibodies contain a radioactive substance such as radioactive iodine that targets and destroys the cancer cells. With this form of therapy, the tumor cells receive a large amount of radiation and normal tissue is spared. Radioisotope-labeled MABs may also prove useful in diagnosing certain cancers.
MABs may also be linked to other forms of Biological Response Modifiers (BRMs) or toxins. When the antibodies latch onto cancer cells, they deliver these substances directly to the tumor, helping to destroy it. A good list of these substances is listed in a SciAM article.
Other applications may exist for MABs. They may help destroy any cancer cells in a patient's bone marrow before an autologous bone marrow transplant - a procedure in which bone marrow is removed from a patient, stored, and later given back to the patient after high-dose chemotherapy and/or radiation therapy.
Monoclonal Antibodies are one of many treatment options for Lymphoma. If you are looking for some assistance with treatment options, there is a FREE tool available to help you understand your treatment options and possible side effects.Click here to sign up for FREE.
Current Monoclonal Antibodies Available or in Late Trials in the United States for lymphoma:
• Rituxan - (generic name rituximab, British trade name MabThera) a nonradioactive bound monoclonal antibody recently approved by the US Food and Drug Administration (FDA)
• Zevalin - an investigative drug from the makers of Rituxan with yttrium-90 radiolabel
• Bexxar - the first radiolabled antibody is in phase III trials and is receiving wider distribution and publicity prior to approval
Resources
Multimedia Resources
Innovative Weapons in the War on Cancer: Monoclonal Antibodies – Video
Radiotherapy: Safety Measures During Therapy – Video
Smarter Drugs Deliver Radiation Directly to Lymphoma Cells - Video
Cancer Radiation Treatment From the Inside – Article
Cutting Edge Therapy: Monoclonal Antibody Treatment for Non-Hodgkin's Lymphoma – Article
Web Resources
NCI Paper on Biological Therapies which includes MABs
The essential article - Scientific American: Immunotherapy for Cancer (9/96) plus a list of tumor killing agents that can be attached to antibodies
Oncology Resource Center (Genentech) - Facts about Monoclonal Antibodies
Genentech Paper - Emerging Clinical Applications of Monoclonal Antibodies in Cancer Immunotherapy
Antibody Therapy article from Cancerbackup (UK) including MabThera (Rituxamab) and Bexxar
Related Articles
For more information on Adult Non-Hodgkin's Lymphoma, please see the following pages:
Lymphoma Information Network: Immunotherapy
Adult Non-Hodgkins Lymphoma: Chemotherapy
Adult Non-Hodgkin's Lymphoma: Treatment
Adult Non-Hodgkin's Lymphoma: Resources
Adult Non-Hodgkin's Lymphoma: Diagnosis
Lymphoma Classification and Types
Adult Non-Hodgkin's Lymphoma: Aggressive NHLs
Adult Non-Hodgkin's Lymphoma: Indolent NHLs
Adult Non-Hodgkin's Lymphoma: Introduction
Other pages you may want to visit:
Lymphoma Information Network
Childhood Non-Hodgkin's Information Pages
