Blood Vessels and Angiogenesis
Just like normal tissues and organs, cancerous tumors need to nourish themselves. In order to do that they need to form blood vessels to get oxygen and nutrients to grow.The process by which blood vessels form is very complex, but is under the influence of growth factors which are produced by normal and abnormal tissues. The main growth factor responsible for blood vessel formation is vascular endothelial growth factor (VEGF), which is produced in larger quantities than normal during cancer growth.
Anti-Angiogenesis Antibodies
Antibodies are tiny particles produced by specialized immune system cells called lymphocytes. When these lymphocytes encounters a foreign substance, they produce antibodies which help attack the intruding foreign substances like viruses and bacteria. Unfortunately, cancer cells look too much like your own normal cells, so the immune system has a harder time recognizing a cancer to attack it in such a manner.Fortunately, it is possible to attack and reduce VEGF circulating in the blood stream by using antibodies synthesized in a laboratory. There are a number of these available, but the one which has been shown to be effective against ovarian cancer is called bevacizumab or Avastin.
Bevacizumab Ovarian Cancer Research Trials
Bevacizumab has been used alone (no additional chemotherapy) against ovarian and primary peritoneal cancer and showed an approximate 18% objective response rate (tumor size decreased on scans) and almost 40% progression free survival at 6 months, which means it kept the cancer at bay without growth in many patients for at least 6 months. For a biological agent alone, these are very promising results.The downside is that when side effects occur, they can be serious. These include bowel perforations, wound healing complications, bleeding, arterial clots, critically high blood pressure increases, severe kidney problems, heart pumping problems, pain, diarrhea and low white blood cell counts, severe brainstem effects and nasal septal perforation (a piece of cartilage inside the nose). These are all unusual, but when they occur, they can be life threatening.
Because of bleeding possibilities, bevacizumab is not used within a month of major surgery. This is due to the finding that it stays around in the body for quite a while in therapeutic doses, probably beyond a month or so.[br[
Since 2006 bevacizumab has been part of a large Phase III Gynecologic Oncology Group (GOG) clinical trial. The protocol examines how effective bevacizumab is in combination with standard chemotherapy is compared to those receiving only the chemotherapy drugs.
As of March 2008, the GOG trial is still ongoing and is available for patients who have had both optimal and suboptimal surgery for ovarian and primary peritoneal cancer.
Reference: Details about this trial on clinicaltrials.gov website
