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* Many patients alive after five years
* Researchers can predict who will respond
By Julie Steenhuysen
CHICAGO, Oct 4 (Reuters) - Patients with the brain cancer glioblastoma treated with a vaccine lived nearly twice as long as those who received radiation and chemotherapy, an encouraging result for a cancer that often kills patients within a year, U.S. researchers said on Monday.
The Celldex Therapeutics Inc (CLDX.O) vaccine works by targeting a mutation in a gene called the epidermal growth factor receptor, which fuels cancer growth.
"It does appear to help patients live much longer than we could have expected," said Dr. John Sampson of Duke University in North Carolina, whose team worked on the study published in the Journal of Clinical Oncology.
Working with researchers at The University of Texas MD Anderson Cancer Center, Sampson's team showed the vaccine killed cancer cells carrying the mutation in all but one patient.
Immune response tests showed patients who developed antibodies after being vaccinated were most likely to respond, giving doctors a good way to see which patients might benefit, Sampson said in a telephone interview.
He said many patients in the study are still alive after five years. "That is pretty unusual with this disease."
Glioblastoma multiforme typically kills half its victims within a year and patients rarely survive more than three years. Sampson remains cautious and says the treatment still needs to be proven in a large-scale clinical trial.
The finding is yet another example of the potential of cancer immunotherapies -- treatments that recruit the immune system to fight cancer.
Earlier this year, the U.S. Food and Drug Administration approved the first cancer vaccine, Dendreon Corp's DNDN.O prostate cancer therapy Provenge.
And a team in June said Bristol-Myers Squibb Co's (BMY.N) immune system treatment ipilimumab helped extend the lives of patients with aggressive melanoma, the deadliest form of skin cancer for which there are few treatment options.
For the midstage brain cancer study, researchers enrolled 35 people with glioblastoma who had undergone radiation and were treated with the chemotherapy drug temozolomide, sold by Merck (MRK.N) under the brand name Temodar, which is thought to boost immune response.
Of those, 18 people got the vaccine and 17 were in a control group. Those who got the vaccine lived an average of 26 months, compared with 15 months for those in the control arm.
Sampson said the vaccine is the first to target proteins only present in cancer cells, which could mean it would have fewer side effects than other cancer vaccines.
He said he has no current financial ties to Celldex, but has received research funding from the company in the past.
Epidermal growth factor receptor mutations are found in many other cancers, and the teams say the vaccine should be tested in other cancers as well. But funding the large studies it will take to prove the vaccine works may be a challenge.
Last month, Celldex's partner Pfizer Inc (PFE.N) pulled out of a strategic partnership to develop the vaccine, and the company said it now plans to develop it on its own.
The National Cancer Institute is spending $14 million over five years to develop a network of clinics to test cancer immunotherapy treatments. (Editing by Maggie Fox and Todd Eastham)