Common virus may help doctors treat deadly brain tumors

A common human virus may prove useful in attacking the deadliest form of brain tumors, according to a study by researchers at Duke’s Preston Robert Tisch Brain Tumor Center. The researchers said the finding is an important step in developing a vaccine that can attack the tumors by enlisting the help of the body’s immune system.

Human cytomegalovirus (HCMV), which infects 50 percent to 90 percent of people at some point during their lives, is active in more than 90 percent of patients diagnosed with glioblastoma multiforme, the most deadly type of malignant brain tumor, said Duane Mitchell, M.D., Ph.D., a brain cancer researcher and lead investigator on the study.

“We don’t know if the virus plays a part in the growth of the brain tumors or whether the presence of the brain tumors leads to a reactivation of the virus,” Mitchell said. “But we do know that the virus has the potential to affect the growth and invasiveness of cancer cells. So if we can target it, we may be able to empower the body’s immune system to fight infected tumor cells and destroy the cancer.”

According to the researchers, a vaccine targeting HCMV likely would be administered to patients following conventional chemotherapy. The immune system’s recovery from chemotherapy is marked by a regenerative burst of new immune cells, and the vaccine would take advantage of this reaction to effect an even stronger immune response to the virus, Mitchell said.

The researchers will publish their findings in the February 2008 print issue of the journal Neuro-Oncology. The study was published early online on October 19, 2007. The research was funded by the National Institutes of Health, The Brain Tumor Society and Accelerate Brain Cancer Cure, a not-for-profit organization that supports research to hasten a cure for brain cancer.

In healthy people with fully functional immune systems, the initial HCMV infection can be symptom-free or it can be associated with mild flulike symptoms. After infection, the virus becomes dormant and stays that way for the life of the infected person. But in people with weakened immune systems -- such as AIDS patients or those undergoing bone marrow transplant -- HCMV can become reactivated and cause more severe illnesses, such as pneumonia.

HCMV’s association with brain tumors was first demonstrated in 2002 by researchers at the University of Alabama - Birmingham, but their results had not been repeated despite several attempts.

“We not only confirmed the virus’ association with the tumors but also saw that patients with glioblastoma multiforme had detectable virus in their bloodstreams, where the comparative group did not,” Mitchell said. “This association may help us assess the success of vaccine treatment, since we will be better able to monitor response in patients, even after their tumors have been removed.”

Based on the results of this study, Duke researchers have developed a vaccine that targets HCMV and are conducting a clinical trial to assess the vaccine’s safety and its effectiveness at building immunity to HCMV in patients with brain tumors. In the trial, which will complete enrollment this year, the vaccine is given monthly to cancer patients in conjunction with chemotherapy for as long as their tumors remain stable.

“We’re encouraged by the early results we’re seeing in the clinical trial and we’re pleased that the initial study enabled us to proceed with testing this vaccine in patients,” Mitchell said. “Because HCMV is present in such a large number of glioblastoma multiforme patients, the development of an effective treatment that targets the virus could have significant implications for this deadly disease.”

Source: Duke University

Related stories:

Brain cells called astrocytes undergo reorganization and may engulf attacking T cells
When virally infected cells in the brain called astrocytes come in contact with anti-viral T cells of the immune system, they undergo a unique series of changes that dramatically reorganize their shape and function, according to researchers at the Board of Governors Gene Therapeutics Research Institute at Cedars-Sinai Medical Center. Intriguingly, the new data indicate that astrocytes may defend themselves from attacking T cells by engulfing (gobbling up) the aggressors.
A Viral Cloaking Device: Biologists show how Human Cytomegalovirus hides from the immune system
(PhysOrg.com) -- Viruses achieve their definition of success when they can thrive without killing their host. Now, biologists Pamela Bjorkman and Zhiru Yang of the California Institute of Technology have uncovered how one such virus, prevalent in humans, evolved over time to hide from the immune system.
Cancer-killing viruses influence tumor blood-vessel growth
Viruses genetically designed to kill cancer cells offer a promising strategy for treating incurable brain tumors such as glioblastoma, but the body's natural defenses often eliminate the viruses before they can eliminate the tumor.
Common virus may serve as target for vaccine in fight against deadly brain tumors
By targeting a common virus, doctors may be able to extend the lives of patients diagnosed with the most prevalent and deadly type of brain tumor, according to a study led by researchers in Duke’s Preston Robert Tisch Brain Tumor Center.
Cedars-Sinai Medical Center opens patient trial of virus that attacks brain cancer cells
A common, naturally occurring virus that attacks cancer cells but appears to be harmless to normal cells is being studied as a possible treatment for malignant, highly aggressive and deadly brain tumors called gliomas. Researchers at Cedars-Sinai Medical Center are among a few in the United States evaluating this experimental therapy.
Gene therapy 'trains' immune system to destroy brain cancer cells and reverses behavioral deficits
A new gene therapy approach that attracts and “trains” immune system cells to destroy deadly brain cancer cells also provides long-term immunity, produces no significant adverse effects and -- in the process of destroying the tumor -- promotes the return of normal brain function and behavioral skills, according to a study conducted by researchers at Cedars-Sinai Medical Center’s Board of Governors Gene Therapeutics Research Institute.
Tumor-killing virus selectively targets diseased brain cells
New findings show that a specialized virus with the ability to reproduce its tumor-killing genes can selectively target tumors in the brains of mice and eliminate them. Healthy brain tissue remained virtually untouched, according to a Feb. 20 report in The Journal of Neuroscience. With more research, the technique could one day offer a novel way of treating brain cancer in humans.
Blood-vessel blocker aids cancer-killing virus
Cancer-killing viruses are a promising therapy for incurable brain tumors, but their effectiveness has been limited in part because immune cells rapidly move in and eliminate them.

News discussion:

Medicine & Health news