CISN - How Does Immunotherapy Work?

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How Does Immunotherapy Work?

How Does Immunotherapy Work?

One immediate goal of research in cancer immunology is the development of methods to harness and enhance the body's natural tendency to defend it against malignant tumors. Immunotherapy represents a new and powerful weapon in the arsenal of anticancer treatments.

Studies indicate that immunotherapy may work in the following ways:

  • Strengthens the immune system
  • Produces anti-cancer activity
  • Reduces side effects from other cancer treatments
  • Improves quality of life

Cytokines

Cytokine is a generic term for a large variety of regulatory proteins produced and secreted by cells and used to communicate with other cells.

Cytokines are diverse and potent chemical messengers secreted by the cells of the immune system. They are the chief communication signals of T cells. Cytokines include interleukins, growth factors, and interferons. Interferons and interleukins are examples of the first immunotherapies for cancer developed decades ago.

Interferons
     

Interferons belong to a group of proteins known as cytokines. They are produced naturally by white blood cells in response to a virus, bacteria, or other foreign intruder. They are made in the body, but can also be produced in the laboratory.

  
     
Image courtesy of the National Center for Biotechnology Information
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  • Interferon-alpha is different than a chemotherapy drug -- it is actually a natural part of the body's immune system. It attaches to other cells and causes a complex series of changes (many of which are unknown), including slowing down the rate of cell division and reducing cells' ability to protect them from the immune system.

Interferon-alpha has been approved by the Food and Drug Administration (FDA) and is now commonly used for the treatment of a number of cancers, including multiple myeloma, chronic myelogenous leukemia, hairy cell leukemia, and malignant melanoma

  • Interferon-beta and interferon-gamma are other types of interferons that have been investigated. Excerpt from' Immunotherapy Cancer Treatment by John W. Park, MD and Christopher C. Benz, MD
Interleukins

As with interferons, interleukins (ILs) are cytokines that occur naturally in the body
and can be made in the laboratory.

  • IL-2 is frequently used to treat kidney cancer and melanoma
     

Interleukin-2 is a type of protein called a cytokine that works to increase the production and function of various components of the body's immune system.

This protein is normally produced in the body, but in small amounts. By increasing levels of IL-2, the increase in immune system components (specifically T cells and natural killer cells) will mount an attack against any cancer cells.

  
     

This is an image of a crystal structure of human interleukin-2 (IL-2) as published by Arkin et al., Binding of small molecules to an adaptive protein-protein interface Proc.Natl.Acad.Sci.USA v100 pp.1603-1608 , 2003
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 they can stimulate the growth of both red and white blood cells which have been destroyed by chemotherapy drugs.

CSF's themselves can produce side effects so they should be used only when needed and patients using them should be monitored closely.
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