Biological Therapies for Cancer: Questions and Answers
5. What are interleukins?
Like interferons, interleukins (ILs) are cytokines that occur naturally in the body and can be made in the laboratory. Many interleukins have been identified; interleukin-2 (IL-2 or aldesleukin) has been the most widely studied in cancer treatment. IL-2 stimulates the growth and activity of many immune cells, such as lymphocytes, that can destroy cancer cells. The FDA has approved IL-2 for the treatment of metastatic kidney cancer and metastatic melanoma.
Researchers continue to study the benefits of interleukins to treat a number of other cancers, including leukemia, lymphoma, and brain, colorectal, ovarian, breast, and prostate cancers.
6. What are colony-stimulating factors?
Colony-stimulating factors (CSFs) (sometimes called hematopoietic growth factors) usually do not directly affect tumor cells; rather, they encourage bone marrow stem cells to divide and develop into white blood cells, platelets, and red blood cells. Bone marrow is critical to the body's immune system because it is the source of all blood cells.
Stimulation of the immune system by CSFs may benefit patients undergoing cancer treatment. Because anticancer drugs can damage the body's ability to make white blood cells, red blood cells, and platelets, patients receiving anticancer drugs have an increased risk of developing infections, becoming anemic, and bleeding more easily. By using CSFs to stimulate blood cell production, doctors can increase the doses of anticancer drugs without increasing the risk of infection or the need for transfusion with blood products. As a result, researchers have found CSFs particularly useful when combined with high-dose chemotherapy.
Some examples of CSFs and their use in cancer therapy are as follows:
- G-CSF (filgrastim) and GM-CSF (sargramostim) can increase the number of white blood cells, thereby reducing the risk of infection in patients receiving chemotherapy. G-CSF and GM-CSF can also stimulate the production of stem cells in preparation for stem cell or bone marrow transplants.
- Erythropoietin(epoetin) can increase the number of red blood cells and reduce the need for red blood cell transfusions in patients receiving chemotherapy.
- Interleukin-11(oprelvekin) helps the body make platelets and can reduce the need for platelet transfusions in patients receiving chemotherapy.
Researchers are studying CSFs in clinical trials to treat a large variety of cancers, including lymphoma, leukemia, multiple myeloma, melanoma, and cancers of the brain, lung, esophagus, breast, uterus, ovary, prostate, kidney, colon, and rectum.
7. What are monoclonal antibodies?
Researchers are evaluating the effectiveness of certain antibodies made in the laboratory called monoclonal antibodies (MOABs or MoABs). These antibodies are produced by a single type of cell and are specific for a particular antigen. Researchers are examining ways to create MOABs specific to the antigens found on the surface of various cancer cells.
To create MOABs , scientists first inject human cancer cells into mice. In response, the mouse immune system makes antibodies against these cancer cells. The scientists then remove the mouse plasma cells that produce antibodies, and fuse them with laboratory-grown cells to create "hybrid" cells called hybridomas. Hybridomas can indefinitely produce large quantities of these pure antibodies, or MOABs.