April 18, 2012 -- A vaccine made from patients' own tumor cells has shown promise against the most common form of adult brain cancer, according to a new, small study.
The vaccine is one of the latest developed to treat cancer, part of a field of research thought to have great promise, though it has proven to be far more challenging than researchers had hoped.
Glioblastoma is the most common form of adult brain cancer, with 17,000 new cases diagnosed each year. The outlook for the cancer is particularly grim; the majority of patients don't survive beyond five years.
The vaccine, called HSPPC-96, uses cells from a patient's own tumor to help the immune system fight the disease.
Using cell parts -- called heat shock proteins taken from the tumor, scientists created versions of the vaccine unique to each patient's cancer, designed to help the immune system recognize and fight the tumor. The approach can be used for any kind of tumor, not just brain cancer.
"This is the ultimate personalized vaccine," said Dr. Pramod Srivastava, director of the Neag Comprehensive Cancer Center at the University of Connecticut, and co-founder of Agenus, the company that developed the vaccine.
In 43 patients with glioblastoma who got the vaccine, 93 percent survived after six months, compared to 68 percent of the 86 patients with the same kind of brain cancer who did not get the vaccine.
"This is a very safe therapy, and one that can potentially extend the lives of patients who really have few options," said Dr. Andrew Parsa, the study's lead author.
The next step is for the vaccine to be tested in a larger number of patients and compared with success rates of more traditional cancer treatments, such as chemotherapy, radiation and surgery. If it proves successful, it would join just a handful of other cancer vaccines, the results of more than two decades of research aiming to provide a more targeted, less toxic approach to treating cancer.
Provenge, a vaccine for treating prostate cancer, was the first cancer vaccine approved by the U.S. Food and Drug Administration, earning the agency's nod in 2010.
The development of other vaccines for melanoma and lung cancer are well underway. Dozens of medical centers and pharmaceutical giants like GlaxoSmithKline and Bristol-Myers Squibb are working on vaccines for many kinds of cancer.
Many researchers are calling the brain cancer vaccine results very promising for a disease with scant successful treatments. But for many who are familiar with cancer vaccine development, the results are part of a similar storyline that's been playing out in the field for the last 20 years: promising early results in a small group of patients, which fail to pan out when put to the scientific world's ultimate test, the large, randomized clinical trial.
Dr. Michael Lotze, co-director of the University of Pittsburgh Cancer Institute, said the most promising progress in cancer vaccines has come from those designed to protect against cancer. The vaccine for hepatitis B has proven to be successful in preventing infection with the virus that can lead to liver cancer.
The same goes for the human papillomavirus vaccine and its success in preventing cervical, vaginal and anal cancers.
But vaccines designed to treat cancer that has already developed have been far more challenging. Some vaccines haven't worked at all. Others actually made tumors grow.
Part of the problem is that the body's immune system recognizes tumors not as a foreign threat, but as a familiar body tissue. Lotze noted that tumors grow for up to 10 years before they reach a size that can be detected by doctors.
In that time, they have become used to the body's immune responses. That makes it doubly hard for a vaccine to prompt the immune system to attack tumor cells.
"The whole field has been sobered by the slow progress that has been occurring over the last 20 years," Lotze said. "But we've seen substantial evidence in recent years that suggests that we're on the right track."
Dr. Hideho Okada, co-leader of the Brain Tumor Program at the University of Pittsburgh Cancer Institute, said using personalized medicine like the brain cancer vaccine offers a big advantage. A vaccine for melanoma used the same approach, but, like a majority of other cancer vaccines so far, failed in early trials.
"That doesn't necessarily mean it wouldn't work for brain cancer," Okada said.
Parsa said randomized controlled trials for the brain cancer vaccine will begin in the next six months.
"We have a very good indication that it will work," Parsa said. "But we don't definitively know how this vaccine will do."