The Role of Angiogenesis in Cancer Growth

Angiogenesis and Inhibitors in Cancer Treatment

diagram of a blood vessel with branches
What is angiogenesis?. Photo©Ugreen

Definition: Angiogenesis

Angiogenesis refers to the formation of new blood vessels in the body. It is a normal bodily process for healing but also plays a role in the growth of cancer.

Angiogenesis in Health and Healing

 Angiogenesis is a normal process that takes place in the body in any situation in which the growth of new blood vessels is required. As such, it is necessary for children to grow, for the uterine lining to grow each month in premenopausal women, and for wounds to heal.

Angiogenesis in Cancer and Metastasis

Angiogenesis is of interest in cancer because cancers require the formation of new blood vessels to grow and metastasize. In order for cancers to grow to be larger than one millimeter (1 mm) angiogenesis needs to take place. Cancers do this by secreting substances that stimulate angiogenesis, and hence, the growth of cancer.

In addition to being a process needed for cancers to grow and invade neighboring tissues, it is necessary for metastasis to occur. In order for cancer cells to travel and set up a new home somewhere beyond their origin, these cells need to bring new blood vessels in to support the growth in their new locations.

Angiogenesis and Vascular Endothelial Growth Factor (VEGF)

Blood vessels are made up of cells called endothelial cells on the inside of the vessels. Substances known as vascular endothelial growth factors, VEGF for short, serve as signals which enable the endothelial cells to grow and create new blood vessels. In other words, they are activators. Blood vessel formation in the body, like many functions, is a balance of activating and inhibitory effects.

Angiogenesis Inhibitors

Angiogenesis inhibitors are a form of targeted therapies, which means they specifically target cancer cells or cells necessary to the growth or spread of cancer.

These medications can interfere with the process of angiogenesis at several different points. Some of these are inhibitory by binding to vascular endothelial growth factor (VEGF) so that it can no longer signal the endothelial cells to grow, and thus they stop the formation of new blood vessels.

Examples of Angiogenesis Inhibitors

Some angiogenesis inhibitors which are currently available for treating cancer include:

  • Avastin (bevacizumab)
  • Nexavar (sorafenib)
  • Sutent (sunitinib)
  • Votrient (pazopanib)
  • Afinitor (everolimus)

Learn more about immunotherapy and how angiogenesis inhibitors work to treat cancer.

Angiogenesis Inhibitors Plus Chemotherapy

A common question is why people would need chemotherapy in addition to angiogenesis inhibitors. Looking at the way that angiogenesis inhibitors works helps to explain this. Angiogenesis inhibitors don't kill cancers, they simply work to prevent them from growing larger and spreading (metastasizing), so in order to get rid of a tumor, chemotherapy has to be used in combination with angiogenesis inhibitors.

Side Effects of Angiogenesis Inhibitors

When angiogenesis inhibitors were first discovered as a treatment for cancer, it was thought that they would have few side effects. 

That was not the case. Just as chemotherapy causes side effects by its actions on normal cells (for example, by stopping cell division in hair follicles, the bone marrow, and the gastrointestinal tract) angiogenesis inhibitors also can cause side effects related to their activity in healthy cells and tissues. Some of the more common side effects are related to:

  • Poor wound healing since angiogenesis inhibitors not only interfere with the ability of cancer cells to make new blood vessels but also interfere with the ability of healthy tissues to make new blood vessels to replace an injury.
  • Clotting in arteries, which in turn can lead to heart attacks and strokes.
  • High blood pressure.

The Future/Clinical Trials

Many medications in this category are being evaluated in clinical trials, and there is hope that attacking cancer from the standpoint of interfering with angiogenesis will be a part of more cancer treatment regimens in the future.

Was this page helpful?

Article Sources