Impotence drugs help treat brain tumors -study

WASHINGTON, July 28 (Reuters) - Impotence drugs may help

carry cancer-fighting drugs through the brain to treat

malignant tumors, U.S. researchers reported on Monday.

Tests in rats showed two erectile dysfunction drugs --

Schering-Plough's <SGP.N> Levitra and Pfizer's <PFE.N> Viagra

-- helped carry a chemotherapy drug past the blood-brain

barrier, the team at Cedars-Sinai Medical Center in Los Angeles

said.

Rats with brain tumors lived 42 days when injected with the

cancer drug adriamycin. But when they also got Levitra, known

generically as vardenafil, the rats survived an average of 53

days. Levitra appeared to be more effective, the researchers

reported in the journal Brain Research.

Levitra and Viagra, known generically as sildenafil, are in

a class of drugs known as PDE5 inhibitors. They were originally

tested as heart drugs because they increase blood flow in small

vessels.

"We chose adriamycin for this study because it is one of

the most effective drugs against brain tumor cell lines in the

laboratory but it has very little effect in animals and humans

because it is unable to cross the blood-brain tumor barrier,"

neurosurgeon Dr. Keith Black, who led the study, said in a

statement.

"The combination of vardenafil and adriamycin resulted in

longer survival and smaller tumor size," Black said.

The blood-brain barrier is a molecular mechanism that keeps

harmful agents out of the brain. Brain tumors grow little blood

vessels to supply themselves with nutrients and these also have

a barrier, called the blood-brain tumor barrier.

Black said the impotence drugs appear to affect the tumor

blood-brain barrier but not the larger blood-brain barrier,

which may help doctors use chemotherapy drugs to kill off brain

tumors without damaging healthy brain tissue, he said.

(Reporting by Maggie Fox; Editing by Will Dunham and Bill

Trott)