June 2, 2008

Brain Tumor Vaccine Could Double Survival Time

U.S. researchers have developed a new cancer vaccine that more than doubled the survival time of people with the most common and deadly type of brain tumor.

The vaccine helps the immune system to attack the tumor and prevents the re-growth of brain tumors in patients who have already been diagnosed and treated with standard regimens including surgery, chemotherapy and radiation.

The vaccine is made by Avant Immunotherapeutics Inc and is licensed by drug giant Pfizer Inc. Doctors hope it will give them more time to treat patients with this aggressive form of cancer.

"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, M.D., Ph.D., a neurosurgeon at Duke and lead investigator on this study.

He said the possibility of doubling expected survival would represent a big step and a lot of hope for this group of patients.

Researchers treated 23 patients with a type of brain tumor called glioblastoma multiforme. Patients treated with the vaccine lived an average of 33 months, whereas patients treated with standard therapy alone lived an average of 14 months.

"That is almost unheard of," Sampson said. "We have one woman who has gone on to have two babies now."

The researchers said it also took longer for tumors to grow back after surgery"”more than double the time it took untreated patients.

Glioblastoma multiforme, a serious form of brain tumor of a type known as a glioma, kills half its victims within a year and patients rarely survive more than three years.

Former Yankees baseball star Bobby Murcer is already being treated with the vaccine and Massachusetts Democratic Sen. Edward Kennedy, who was diagnosed with a malignant glioma last month, could be among the possible candidates for future treatment.

"Kennedy may well be a candidate. We don't know if he is interested at this point," Sampson said in an interview.

The study treated the 23 patients at Duke and at M.D. Anderson Cancer Center. All patients had been diagnosed with GBMs, and had been treated with standard therapy.

The vaccine targets a mutation of a very common structure known as a receptor on the tumor cells, the epidermal growth factor receptor. This mutation is only found in cancer, not in normal tissues.

Patients in the trial received vaccine injections monthly and were given a chemotherapeutic agent called temozolomide in conjunction with the vaccine treatments.

"The temozolomide is thought to enhance the immune response to the EGFRvIII," Sampson said.

He said the patient's immunity responses had been "phenomenal".

"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 phase II study of the vaccine showed similar results to the first and now a larger randomized study is currently enrolling patients at 24 sites across the United States.

The results have been enough to attract the interest of Pfizer Inc, which in April agreed to pay a total of more than $400 million for rights to market the vaccine.

"This is probably one of the biggest if not the biggest immunotherapy deals that has been made," Sampson said.

Avant shares surged on the news. They were up more than 30 percent in midday trading at $18.57. Pfizer was down slightly at $19.16 a share.

The vaccine has caused virtually no side effects; swelling at the injection site is often a patient's only complaint.

According to the American Cancer Society, about 22,000 malignant tumors of the brain or spinal cord will be diagnosed this year in the United States, and about 13,000 people will die from them.


On the Net:

Duke University Medical Center

Avant Immunotherapeutics Inc