Cancer can originate in a number of different cell types. One such cell type is the B-cell. B-cells are one of five kinds of lymphocytes found in the body. As part of the immune system, their function is largely to create antibodies against antigens. If such antigens are foreign to the immune system, B-cells help activate our body’s fight response.
B-cells are manufactured in the bone marrow and distributed throughout the body via the blood stream. As such, cancers associated with bone marrow and the lymph node system may be caused by cancerous B-cells. Examples include non-Hodgkins lymphoma, prolymphocytic leukemia (PLL) and hairy cell leukemia (HCL).
Using B-Cells in Cancer Treatment
B-cell targeting has become a heightened topic of research in the study of cancer treatment. Because B-cells are attracted to antigens, researchers have begun to generate antibodies that are specifically meant to bind with these unique cells. The goal of this binding process is to either administer cytotoxic drugs directly to the cancerous cell, or to trigger an internal immune response that attacks and kills the cell.
Direct B-cell targeting is seen as a particularly promising area of cancer research due to the large number of proteins found on the exterior surface of these lymphocytes. Each protein beckons different types of antibodies, thereby giving researchers a number of different avenues of attack (think of it as an archer having 20 targets to aim at instead of just one).
CD20 B-Cell Cancer Medications
The Food & Drug Administration (FDA) has already approved a handful of chemotherapy drugs that target B-cells. The majority of these medications bind to the B-cell surface protein known as CD20. CD20 is a protein present on all mature B-cells. It is additionally expressed on cancerous B-cells. Current medications that target CD20 include rituximab (Rituxan or MabThera), Ibritumomab tiuxetan (Zevalin) and tositumomab (Bexxar). These drugs are used for the treatment of the following disorders:
- Rituximab: various types of lymphomas and leukemias
- Ibritumomab tiuxetan: non-Hodgkins lymphoma
- Tositumomab: non-Hodgkins lymphoma
All three of these medications work by delivering a cytotoxic chemical directly to B-cells, thereby destroying them. This cell death occurs in both healthy and cancerous B-cells. The goal is to extinguish all adult B-cells and spur the growth of a new generation of healthy cells.
Several other CD20 chemotherapy drugs are currently undergoing clinical trials. One such medication, created by Genentech, contains an anti-CD20 monoclonal antibody. This antibody has been shown to bind to CD20, opening the door for cell destruction via cytotoxic chemicals.
CD40 B-Cell Cancer Medications
CD40 is a surface protein that is present in a variety of cell types, including B-cells and cancerous B-cells. CD40 is seen as a promising protein of study because it not only can be targeted for antibody binding, but also triggers indirect cell death by activating the immune system. This synergistic effect is currently being tested in several clinical trials. Initial reports indicate positive results without excessive toxicity to healthy cells.
History of B-Cell Cancer Medication
The role of B-cells in certain lymphomas and leukemias has long been known. Developed in 1986 at IDEC Pharmaceuticals, Rituximab was the first successful B-cell drug ever produced. After rigorous clinical trials, the FDA finally approved it in 1997. Five years later, Ibritumomab tiuxetan was brought to market and Bexxar was approved by the FDA in 2003.
