Biological therapy uses drugs known as biological response modifiers (BRMs) to treat cancer. These drugs act in a number of ways to provoke a strong immune-system response or restore immune function. They are used in the treatment of a number of diseases, including cancer. In cancer treatment, BRMs are used to both help the body identify and destroy cancer cells and to reduce the side effects of chemotherapy.

Other BRMs work directly on the cancer cells rather than with the immune system. These agents can slow the growth of the cells or promote their development into more normal behavior. In addition, some BRMs are used to help combat damage in the body that can occur with cancer treatments, such as chemotherapy.

Biological therapy drugs have three major effects on the immune system:

• Repair. Drugs such as colony-stimulating factors help restore levels of red blood cells, white blood cells and platelets that are sometimes damaged during chemotherapy and radiation therapy. These cells are important to the body’s well-being.
  
  
• Stimulate. Drugs such as interferons, monoclonal antibodies and cancer vaccines help the immune system to recognize and attack cancer cells. They also can work directly against cancer cells and interfere with their growth and development.
  
  
• Enhance. Drugs such as interleukins can boost the production and the activity of certain white blood cells, giving the immune system greater power in attacking cancer cells.
  

Biological therapy drugs may be the sole means of treating a patient’s cancer, or may be used in combination with other treatments.