A small clinical study released on Monday said an experimental vaccine can stimulate the immune system to attack the glioblastoma multiforme (GBM) tumor and double the survival of patients.

The 23 patients in the trial who suffered from large GBM tumors were treated with the vaccine. They lived an average of 33 months compared to the average 14-month survival time of those receiving standard treatment alone.

The study also showed the vaccine can slow the return of the tumor after surgery. The tumor for those treated with the vaccine reappeared in 16.6 months compared to the usual six months.

"This vaccine represents a very promising therapy for a cancer that comes out of the blue and robs people of something most of us take for granted -- time," said John Sampson, a neurosurgeon at Duke and lead investigator on this study.

Sen. Edward Kennedy had undergone a surgery to remove such kind of tumor and he could possibly benefit from the vaccine, Sampson said.

The vaccine produced by the U.S. firm Avant Immunotherapeutics Inc is described without virtually side effects, and has been licensed by drug giant Pfizer Inc.

"One of the worries about immune therapies is that the immune system may start attacking itself. So far, that has not happened," said Sampson.

A much larger clinical trial was planned for later this year.

(Agencies via Xinhua News Agency June 4, 2008)