Nov 1, 2004 /PSA Rising/ New York. UK medical researchers have discovered that a type of vascular endothelial growth factor (VEGF) found in normal tissue, including blood, can prevent cancers from growing.
Dr Steve Harper and Dr. David Bates, two super-enthusiastic physiologists at Bristol University, published their findings in the scientific cancer journal, Cancer Research, today. Bates is a British Heart Foundation Lecturer at the university and Harper is Senior Research Fellow in the Microvascular Research Laboratories.
The growth of any cancer, Bates explains, depends on its ability to maintain a blood supply that will deliver nutrients. For a cancer to grow from the size of a pinhead to that of a golf-ball, the blood supply of the tumour has to grow with the expansion of the tumour itself. Most forms of VEGF help this blood vessel growth.
The new form of VEGF, VEGF165b, which was discovered by the same team in 2002, inhibits the growth of new blood vessels required for tumours to grow above one millimetre.
They have also found that this form of VEGF is generally found in many normal parts of the body, including the prostate, but not in prostate cancer, and have established how this form of VEGF works on blood vessels.
The identification of how this new form of VEGF works, and its effects on tumours, means that it could be possible to prevent tumour growth by starving the tumour using the body's own anti-cancer agent, VEGF165b.
The advantage of using VEGF165b over established compounds to treat cancer is that VEGF165b is a natural protein produced by the body under normal circumstances.
Many new cancer therapies are based on starving the tumour of nutrients by attacking the tumour blood supply rather than the cancer cells. Blocking VEGF using antibodies has recently been shown to be effective in large-scale trials in colorectal cancer in the United States.
New blood vessel growth is also necessary for many normal body functions. These include the development of the embryo and, in adults, wound healing, the development of the placenta in pregnancy and of muscles during physical training programmes. However, it is thought that adults can live healthily without blood vessel growth for extended periods of time. This blood vessel growth is controlled by many factors, but VEGF is the most powerful factor.
Dr Bates, said: "Now that we have found out that this protein works in living tissues, we need to find the best way of using it in cancer, with tumour models. We also need to try it in models of other diseases where blood vessel growth is necessary, such as diabetes, age related macular degeneration and arthritis."
VEGF 165 b has been patented by the University of Bristol for its use in angiogenesis associated disease. Unfortuately, Bates and HArper are not optimistic about producing a usable drug in the near future.
"The work that we have recently published," Bates said, "is scientific evidence based on information we have found from patients suffering with prostate and other cancers. We, and other scientists around the world, will be continuing this research using models of cancer in a variety of different systems and a variety of different tumours. We will not be doing any human trials for the foreseeable future (within the next two years). "
In fact the chemical does not yet exist in the form of a drug. "We do not have purified VEGF 165 b in a form that can be given to patients, we do not know how best to administer it, and we are not at all sure that it will make the slightest difference to your condition," Bates said.
"It will take at least two years before we will be able to set up safety trials. I'm sorry we cannot be more positive."
Stil, lthe potential is there. Dr Harper added: "After two years of hard work it is a big step to show that this protein works in real cancers. We hope to be able to take this forward in the next few years to work out how to treat patients with cancer, eye disease and other conditions where this protein is important."
So far all the work on Vegf has been funded by charities. "We are currently seeking industrial partners to exploit this technology," Bates said.
Meantime some clinical trials in cancer using angiogenesis inhibitors are ongoing. For details check the NCI webpage:
Angiogenesis inhibitors in clinical trials
The Bristol team's research was published in Cancer Research 64, 7822-7835, November 1, 2004 with the title VEGF165b, an Inhibitory Vascular Endothelial Growth Factor Splice Variant: Mechanism of Action, In vivo Effect On Angiogenesis and Endogenous Protein Expression
University of Bristol Microvascular Research Laboratories Department of Physiology
Charities that support this work
a. The British Heart Foundation
b. The Association for International Cancer Research
c. The Richard Bright VEGF Research Trust
d. Diabetes UK
e. Cancer Research UK
f. Prostate Research Campaign
g. National Kidney Research Fund
