MONDAY, Aug. 15 (HealthDay News) -- Combination gene therapy has proved effective against deadly glioblastoma multiforme (GBM) brain cancer in rats, U.S. researchers report.

GBM is the most common and deadly of brain cancers in humans, with patients usually dying within six to 12 months of diagnosis.

Reporting in the Aug. 15 issue of Cancer Research, researchers at Cedars-Sinai Medical Center in Los Angeles used a genetically engineered virus to deliver two proteins -- RAdTK and RAdFlt3L -- directly into the brains of rats with GBM.

RAdTK is a protein that kills cancer cells, and RAdFlt3L stimulates immune cells in the brain.

After six months of treatment with the combined gene therapy, 70 percent of the rats were still alive and their large GBM tumors had shrank significantly or completely disappeared.

"Our study shows that GBM tumors were completely eliminated in lab rats, likely because the two proteins increase the production of fully mature immune cells within the brain," study senior author Maria Castro, co-director of the Gene Therapeutics Research Institute at Cedars-Sinai, said in a prepared statement.

"This suggests that combined RAdFlt3L and RAdTK gene therapy may ultimately prove an effective treatment for patients undergoing clinical trials with GBM," Castro said.

More information

The U.S. National Cancer Institute has more about brain tumors.