CHICAGO (Reuters) - A cancer vaccine more than doubled the survival time of people with the most common and deadly type of brain tumor, U.S. researchers said on Monday.
The vaccine, made by Avant Immunotherapeutics Inc and licensed by drug giant Pfizer Inc, enlists the help of the immune system to attack the tumor.
Researchers treated 23 patients with a type of brain tumor called glioblastoma multiforme. They have lived, on average, 33 months, said Dr. John Sampson of Duke University, who presented the study at a meeting of the American Society of Clinical Oncology in Chicago. “That is almost unheard of,” Sampson said in an interview.
“We have one woman who has gone on to have two babies now,” Sampson said.
Patients given standard therapy alone lived on average 14 months.
It also took far longer for tumors to grow back after surgery. In people treated with the vaccine, this so-called time to progression was 16.6 months, more than double the usual six months.
Avant shares surged on the news, rising nearly $4 or about 28 percent to $17.98 on Monday. Pfizer dipped slightly to close at $19.18.
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.
Massachusetts Democratic Sen. Edward Kennedy was diagnosed with a malignant glioma last month and the vaccine could be one among several options he might try, Sampson said.
“Kennedy may well be a candidate. We don’t know if he is interested at this point,” Sampson said in an interview.
Kennedy underwent a 3-1/2 hour surgery at Duke in North Carolina on Monday, which his doctor described in a statement as “successful.”
“In order for Kennedy to qualify for the vaccine, the surgery would need to have removed all of the tumor,” Dr. Mark Gilbert of the University of Texas M.D. Anderson Cancer Center told reporters at a media briefing.
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. It occurs in about 30 percent of glioblastomas, Gilbert said.
The vaccine is coupled with a chemotherapy drug called temozolomide, sold by Schering-Plough Corp. under the brand name Temodar, which is thought to boost the immune response. “The immune responses these patients are getting are phenomenal,” Sampson said.
One of the worries about immune therapies is that the immune system may start attacking itself. So far, that has not happened, Sampson said.
A second study of the vaccine that followed a slightly different design and dosing schedule in 21 patients resulted in a median survival time of 26 months, compared to the typical 15-month survival for similar patients who just got standard therapy.
Gilbert said the results were promising but “very preliminary.”
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 $50 million for rights to the vaccine in a deal that could eventually be worth more than $400 million to Avant if the drug is approved and certain milestones are reached.
Pfizer, whose stock is at a 10-year low, is in need of a big win. “This is probably one of the biggest if not the biggest immunotherapy deals that has been made,” Sampson said.
“If this works, I think there will be more investment in vaccines,” he said.
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, according to the American Cancer Society.
Editing by Maggie Fox and Cynthia Osterman