Re: Gleevec Attacks Prostate Cancer in Mice

[Guest guest]

I find it baffling that they can claim that Gleevec has this effect

when they didn't even test Gleevec independently for this purpose.

They used Gleevec in combination with Taxol which is already

approved for front line treatment for prostate cancer. How in the

world can they claim Gleevec had any effect at all when their data

is confounded by the use of another drug. Unless I'm missing

something here, I find this irresponsible reporting.

On a related note, I know of a patient who has had CML for more than

5 years, has been on Gleevec the whole time, and still developed

prostate cancer in spite of his Gleevec usage so personally, I doubt

the usefullness of using Gleevec in prostate cancer treatment.

Tracey

>

> Univ Of Texas - MD Cancer Center

> July 2006

> Gleevec Attacks Prostate Cancer in Mice

> Drug Works by Destroying Tumor's Blood Supply

>

> Imatinib (GleevecR), which has been successful in treating some

> leukemias and gastrointestinal stromal tumors (GIST), stopped the

growth

> of prostate cancer that had spread in mice, according to a report

in the

> June 7 issue of the Journal of the National Cancer Institute.

>

> M. D. researchers tested Gleevec by first injecting two

groups

> of mice with a chemotherapy-resistant form of prostate cancer. One

group

> received a combination of Gleevec and paclitaxel (TaxolR). The

second

> group did not receive treatment.

>

> Fewer tumors and less metastasis in Gleevec group

>

> In the group given the Gleevec combination:

>

> a.. Tumors were found in only 4 of 18 mice

> b.. Median tumor weight was one-tenth of a gram

> c.. Cancer spread to the lymph nodes in three cases

> In the control group not given the combination:

>

> a.. Tumors grew in all 19 mice

> b.. Median tumor weight was 1.3 grams

> c.. Cancer spread to the lymph nodes in all mice

> Gleevec succeeds by cutting off tumor's blood supply

>

> The research team used an extremely drug-resistant form of prostate

> cancer, which they designed, to emulate the grim clinical reality

of

> prostate cancer that has spread into the bone, says Isaiah Fidler,

> D.V.M., Ph.D., chair of M. D. 's Department of Cancer

Biology

> and director of the Cancer Metastasis Research Center at M. D.

.

>

>

> " Why, then, did it work so well in the animal? Because we didn't

attack

> the tumor, we attacked the blood vessels, " says Fidler, the paper's

> senior author. " We target and destroy the vasculature that provides

> oxygen and nutrients to tumor cells. "

>

> In their report, Fidler and colleagues show that Gleevec killed

> tumor-related blood vessel (endothelial) cells by inactivating the

> platelet-derived growth factor receptors (PDGF-R) on the cell

surface.

>

> Activation of PDGF-R:

>

> a.. Stimulates the birth of new blood vessels

> b.. Promotes cell division and migration

> c.. Inhibits apoptosis, a form of cell suicide

> All are harmful effects that fuel growth of cancer cells.

>

> With Gleevec preventing activation of PDGF-R, Fidler says, the

> endothelial cells died by apoptosis first, with tumor cells

following

> suit one to two weeks later.

>

> Additional therapies needed for advanced cancer

>

> Fidler said the findings are a good example of the " seed and soil "

> hypothesis in metastasis - the deadly spreading of a cancer from

its

> organ of origin to other organs. This process kills 90% of all

patients

> who die from their disease.

>

> Gleevec had an effect by itself, but the best result came from the

> pairing with Taxol, which induces cell death in non-resistant

cancer

> cells. Taxol is frontline therapy for prostate cancer, but

eventually

> loses its effect as resistant tumor cells proliferate.

>

> Cancer cells are biologically diverse and genetically unstable,

Fidler

> says, so it is highly unlikely that a single therapy will prevail.

This

> necessitates multiple modes of attack on the disease.

>

> Gleevec has been effective in treating chronic myelogenous

leukemia and

> GIST and is being studied as a treatment for other cancers.

>

> - From staff reports

>

> Resources:

>

> Isaiah Fidler, D.V.M., Ph.D.

>

> Department of Cancer Biology

>