- What is angiogenesis?
Angiogenesis is the formation of new blood vessels. Angiogenesis is a process
controlled by certain chemicals produced in the body. Some of these chemicals
stimulate cells
to repair damaged blood vessels or form new ones. Other chemicals, called
angiogenesis inhibitors, signal the process to stop.
- Why is angiogenesis important in cancer?
Angiogenesis plays an important role in the growth and spread of cancer.
New blood vessels “feed” the cancer cells with oxygen and nutrients,
allowing these cells to grow, invade nearby tissue,
spread to other parts of the body, and form new colonies of cancer cells.
- How can angiogenesis be stopped in tumors?
Because tumors cannot grow or spread without the formation of new blood
vessels, scientists are trying to find ways to stop angiogenesis. They are
studying natural and synthetic angiogenesis inhibitors, also called antiangiogenic
agents, in the hope that these chemicals will prevent or slow down the growth
of cancer by blocking the formation of new blood vessels.
- Are any angiogenesis inhibitors currently being
used to treat cancer in humans?
Yes. The U.S. Food and Drug Administration (FDA) has approved bevacizumab
(Avastin®)
for use with other drugs to treat colorectal
cancer that has spread to other parts of the body, some non-small
cell lung cancers, and some breast cancers that have spread to other parts
of the body. Bevacizumab was the first angiogenesis inhibitor proven to delay
tumor growth and, more importantly, extend the lives of patients.
The FDA has also approved other drugs with antiangiogenic activity as cancer
therapies for multiple myeloma, mantle cell lymphoma, gastrointestinal stromal
tumors (GIST), and kidney cancer.
Researchers are also exploring the use of these drugs to treat other cancers
(see Question 8).
- What are the advantages of angiogenesis inhibitors?
Angiogenesis inhibitors usually have only mild side effects and are not
toxic
to most healthy cells. Tumors do not seem to develop a resistance to angiogenesis
inhibitors, even when given over a long period of time, unlike the resistance
seen when chemotherapy
drugs are used.
Angiogenesis inhibitors seem to help some chemotherapy drugs and radiation
therapy work more effectively when given in combination.
- What are the limitations of angiogenesis inhibitors?
Angiogenesis inhibitor therapy may not necessarily kill tumors, but instead
may keep tumors stable. Therefore, this type of therapy may need to be administered
over a long period. Because angiogenesis is important in wound
healing and in reproduction, long-term treatment with antiangiogenic agents
could cause problems with bleeding, blood
clotting, heart function, the immune
system, and the reproductive
system (1).
- Does angiogenesis inhibitor therapy have any complications
or side effects?
A patient’s immune system may be compromised, making the patient more
susceptible to infection
and causing wounds to heal poorly, if at all. Patients may experience reproductive
problems, and damage to the fetus
is likely if a patient becomes pregnant while taking the antiangiogenic drug.
Heart problems and high blood pressure could be made worse, and bleeding or
blood clots could increase (1).
Since angiogenesis inhibitor therapy is still under investigation, all of
the possible complications and side effects are still unknown.
- What does the future hold for angiogenesis inhibitor
therapy?
Other angiogenesis inhibitors are currently being tested in clinical
trials (research studies) but have not yet been shown to be effective
against cancer in humans. If these angiogenesis inhibitors are proven to be
both safe and effective in treating human cancer, they may be approved by
the FDA and made available for widespread use.
The list below includes cancers that are being studied in active phase III
treatment clinical trials using angiogenesis inhibitors. The clinical trials
are in the National Cancer Institute’s (NCI) clinical trials database
at http://www.cancer.gov/clinicaltrials/search
on the Internet. For information about how to search the database, see “Help
Using the Basic Clinical Trial Search Form” at http://www.cancer.gov/clinicaltrials/basic-search-form-help
on the Internet.
Types of Cancer in Active Phase III Treatment Clinical Trials of
Angiogenesis Inhibitors:
For more information about NCI's clinical trials database and other cancer-related
information, call NCI’s Cancer Information Service at 1–800–4–CANCER
(1–800–422–6237).