Biological therapy (sometimes called immunotherapy, biotherapy, or biological response modifier therapy) is a relatively new addition to the family of cancer treatments that also includes surgery, chemotherapy, and radiation therapy.

Biological therapies use the body's immune system, either directly or indirectly, to fight cancer or to lessen the side effects that may be caused by some cancer treatments. They include monoclonal antibodies, cytokines, vaccines, bacillus Calmette-Guérin therapy, oncolytic virus therapy, gene therapy, and adoptive T-cell transfer therapy.

They act in the following ways:
• stop, control, or suppress processes that permit cancer growth
• make cancer cells more recognizable and, therefore, more susceptible to destruction by the immune system
• boost the killing power of immune system cells, such as T cells, NK cells, and macrophages
• alter the growth patterns of cancer cells to promote behavior like that of healthy cells
• block or reverse the process that changes a normal cell or a precancerous cell into a cancerous cell
• enhance the body's ability to repair or replace normal cells damaged or destroyed by other forms of cancer treatment, such as chemotherapy or radiation
• prevent cancer cells from spreading to other parts of the body

National Cancer Institute. Biological therapies for cancer. Internet. Accessed on May 27, 2016.