Chemicals called cannabinoids could starve tumours to death by halting the growth of blood vessels that feed it, the Complutense University team hope.
By studying mice, the team has shown for the first time how these chemicals block vessel growth.
Their study, published in Cancer Research, also shows the treatment appears to work in humans.
| | This research provides an important new lead compound for anti-cancer drugs Dr Richard Sullivan, Cancer Research UK |
Glioblastoma multiforme is the most common brain cancer and is notoriously difficult to treat.
It can evade destruction by radiotherapy, chemotherapy and surgery.
Dr Manuel Guzmán and colleagues set out to determine whether they could prevent the cancer from growing by destroying its blood supply.
Previous research has shown cannabinoids block the growth of blood vessels in mice, but little is known about how these chemicals do this and whether they might do the same in human tumours.
Starving tumours
The researchers first gave mice cancer resembling the human form of brain cancer they wanted to study.
They then treated the mice with cannabinoid and examined the genes of the mice.
The activity of genes associated with blood vessel growth in tumours through the production of a substance called vascular endothelial growth factor (VEGF) was reduced.
Cannabinoids appeared to stifle VEGF production by increasing the activity of a substance that controls cell death, called ceramide.
Lead researcher Dr Guzmán said: "As far as we know, this is the first report showing that ceramide depresses VEGF pathway by interfering with VEGF production."
Their next challenge was to see if cannabinoids had the same effect in humans.
They took samples from two patients with glioblastoma multiforme who had not responded to surgery, chemotherapy and radiotherapy treatment.
Treatment for humans
Samples were taken before and after the patients were treated with cannabinoid solution infused directly into the tumour.
In both patients, VEGF levels in the tumour were reduced following treatment with cannabinoids.
Although they only looked at two patients, the researchers hope their findings could lead to new treatments.
"The present findings provide a novel pharmacological target for cannabinoid-based therapies," said Dr Guzmán.
Dr Richard Sullivan, Head of Clinical Programmes at Cancer Research UK, said: "This research provides an important new lead compound for anti-cancer drugs targeting cancer's blood supply.
"Although this work is at an early stage of development, other research has already demonstrated that VEGF is an important drug target for a range of cancers.
"The key now will be to show further activity in pre-clinical cancer models, find out in which combinations cannabinoids show greatest activity and formulate a product that can be tested in man.
"It is important to note that cannabinoids would need to generate very strong data in the future as there are already a number of VEGF inhibitors in clinical development," he said. - BBC
In "Cannabis extract makes brain tumors shrink, halts growth of blood vessels," Medical News Today gives other details about the tests done on human patients.
[The researchers] selected two patients who had glioblastoma multiforme and had not responded to chemotherapy, radiotherapy or surgery. The scientists took samples from them before and after treating them with a cannabinoids solution -- this was administered directly into the tumor.
Amazingly, both patients experienced reduced VEGF levels in the tumor as a result of treatment with cannabinoids.
The researchers said that the results were encouraging. In order to be sure about their findings they need to carry out a larger study, they said.
 | Here you can see the effect of the treatment on the two patients with brain cancers. VEGFR-2 activation is shown in green and its expression in red. Cell nuclei are stained in blue. Relative values of activated-VEGFR-2 pixels are displayed in parentheses and total-VEGFR-2 pixels in square brackets are given for the two patients per cell nucleus. (Credit: Cancer Research). |
For more information, you also can read this news release from the American Association for Cancer Research, "Cannabis ingredient inhibits VEGF pathway required for brain tumor blood vessels."
The research work has been published by the Cancer Research journal under the title "Cannabinoids Inhibit the Vascular Endothelial Growth Factor Pathway in Gliomas." Here are two links to the abstract and to the full paper (PDF format, 7 pages, 732 KB). The above illustration comes from this paper.
Sources: Shaoni Bhattacharya, New Scientist, August 15, 2004; Medical News Today, August 15, 2004; American Association for Cancer Research news release, via EurekAlert!, August 15, 2004; Cancer Research, Vol. 64, Num. 16, Pages 5617-5623, August 15, 2004
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