TUESDAY, Oct. 5 (HealthDay News) -- Adding a new vaccine to standard therapy extended survival for people with the most deadly type of brain cancer in a small study.

Researchers from Duke University Medical Center and the University of Texas M.D. Anderson Cancer Center report that the case-control study included 35 patients newly diagnosed with the brain cancer, known as glioblastoma (GBM). The patients were divided into two groups: Both received surgery, radiation and the chemotherapy drug temozolomide, but one group of 18 patients also began receiving injections of the new vaccine one month after completing radiation and continued to receive the vaccine as long as it appeared to be effective.

Median survival time for those in the vaccine group was 26 months, compared with 15 months for the control group. Progression-free survival was 14.2 months in the vaccine group, compared to 6.3 months in the control group.

The vaccine appeared to stimulate an immune response in approximately half of the patients who received it, suggesting such responses were linked to increased survival time, "but the numbers are so small that we cannot conclude this with any degree of certainty," Dr. Amy Heimberger, co-lead investigator from M.D. Anderson, said in a news release from Duke.

The vaccine knocks out a growth factor associated with the most aggressive form of the brain cancer.

"About a third of all glioblastomas are fueled by a very aggressive cancer gene, called EGFRvIII; these tumors are the 'worst of the worst,'" Dr. John Sampson, a professor of neurosurgery at Duke University Medical Center, said in the news release.

The presence of EGFRvIII allows cancer cells to multiply out of control, seeding new tumors throughout the brain, the researchers explained. Even with advances in chemotherapy and radiation, prognosis for patients with glioblastoma is poor, with an average survival time of one year after diagnosis.

About 10,000 new cases of glioblastoma appear in the United States every year.

"Our study showed that the vaccine eliminated all of the cancer cells carrying this marker in all but one of our study participants," study senior author Dr. Darell D. Bigner, director of the Preston Robert Tisch Brain Tumor Center, said in the news release. (Bigner is one of three scientists who discovered the gene variant EGFRvIII.)

The vaccine is known variously as CDX-110 by Celldex Therapeutics or PF-04948568 by Pfizer.

The study appears online Oct.4 in the Journal of Clinical Oncology.

Drs. Bigner, Heimberger and Sampson, along with Duke University and M.D. Anderson, have potential conflicts of interest from consulting agreements, stock options and possible licensing fees, according to background material for the study. Duke and M.D. Anderson have plans in place to manage potential conflict of interest, the statement said.

More information

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