Biological therapy is a form of treatment that uses the body’s own immune system to fight cancer.  This type of cancer treatment can work either directly or indirectly to enhance, repair or stimulate the immune system’s response to cancer. There are also certain types of biological therapy that may be used to reduce the side effects of cancer treatments such as chemotherapy.

Biological therapy uses specific drugs, known as biological response modifiers (BRMs).  Each BRM works differently with the body to fight the cancer or improve the health of the patient undergoing cancer treatment. These drugs are substances found in the immune system, such as antibodies and cytokines, but they are produced in a laboratory when they function as BRMs. 

The BRMs used in biological therapy include:

• Interferons (IFNs). Drugs that mimic cytokines, a protein in the immune system that activates certain immune system cells) made by the body. Interferons also help promote the transition of cancer cells into cells of normal growth.
  
  
• Interleukins (ILs). Another drug group that mimics a cytokine made by the body. ILs help the body produce and stimulate some white blood cells to attack invading cancer cells.
  
  
• Monoclonal antibodies (MOABs). Natural antibodies are proteins that fights off infections. Monoclonal antibodies are created artificially and can be targeted against specific areas of cancer cells. MOABs help the body recognize cancer cells so they can be destroyed by the immune system.
  
  
• Colony–stimulating factors (CSFs). Sometimes called hematopoietic growth factors, these drugs stimulate bone marrow stem cells to divide and develop into white blood cells, red blood cells and platelets. Cancer treatments such as chemotherapy can lower the counts of these blood cells. CSFs can help replace the cells.
  
  
• Nonspecific immunomodulating agents. Substances that stimulate and indirectly augment the immune system.
  
  
• Antiangiogenesis. A new biological therapy that shows promise in fighting cancer. This strategy prevents tumors from generating new, small blood vessels necessary for the tumor to sustain itself.
  
  
• Gene therapy. This treatment is based on altering a cell's genetic material to fight or prevent disease. It is an experimental method that involves introducing genetic material, such as DNA, into an individual’s cells to fight cancer.
  
  
• Cancer vaccines. Researchers are developing vaccines that either prevent the development of cancer or treat existing cancers by helping the patient’s body to recognize and fight cancer, and keep it from recurring.
  
  
• Epithelial growth factor receptor (EGFR) inhibitors. EGFR has been associated with aggressive cancer cell growth in tumors. EGFR inhibitors are drugs that may help prevent the development and progression of cancer in certain tumors.

Biological therapy drugs are administered in various ways, depending on the type of treatment. Oral and some injection treatments may be taken at home, while  intravenous administration may require visits to a clinic or hospital. Treatment doses and schedules vary and can range from daily to once every few months.

The medications may be taken alone or in combination with other treatments, such as chemotherapy or radiation.  Many of the therapies may be available only through clinical trials. A patient’s medical oncologist can best determine if biological therapy is a viable treatment option.

As with other cancer treatments, biological therapy can cause side effects. The most common side effects include rashes or swelling at the injection site and flu-like symptoms.