Conventional treatments have never offered much help to patients with brain cancer. So doctors at the University of California-San Francisco are trying an entirely new approach, enlisting the patient's own immune system to attack the tumor.
If successful, the so-called cancer "vaccine" would give hope to patients with glioblastoma, the most common and aggressive type of brain cancer that claimed the life of Sen. Edward Kennedy and 17,000 others every year.
"We need alternative treatments, using the immune system," said Andrew Parsa, a UCSF neurological surgeon who is leading the study of the vaccine, called Oncophage, with $150,000 in funding from the National Brain Tumor Society and other patient groups and another $150,000 from the federal government.
"Just like the vaccines we give for measles, mumps and the flu, the idea is to prevent cancer from coming back" after surgery, said Parsa.
So far, the agent is proved to trigger an immune response in patients -- but only time will tell whether this response succeeds in prolonging lives.
University scientists seek to expand the study -- currently eight patients with newly diagnosed cancer and 30 patients with recurrent cancer are enrolled in the trial -- so they can learn more about the vaccine's potential effectiveness. It seems safe and well-tolerated by patients, causing few or no side effects, said Parsa.
Traditional chemotherapeutic drugs don't work
well in combating this type of cancer. Part of the problem is the body's blood-brain barrier, which is designed to shield the organ from chemicals -- but also blocks lifesaving therapies from reaching it.
Tumor cells also become quickly resistant to medicines.
Vaccines, also called immunotherapies, take a different approach. Using a multistep approach, they are created from a patient's own tumor. First, doctors remove the cancer cells. Then they send them to Massachusetts-based biotech company Antigenics for processing. Then they inject them back into the patient.
The goal is to provoke the body's immune system cells, called T cells, to seek out and destroy the cancer cells.
"It's like a little flu shot," said patient Joyce Wheatley, 58, who has received four injections -- two in her chest and two in her arms -- for a cancer diagnosed in July. Surgery removed 95 percent of the tumor; in addition to the vaccine, she'll get chemotherapy and radiation.
"It is pretty exciting. Hopefully it will help," said Wheatley, who drives to treatments from the small Merced County town of Winton. Volunteering in the study "could help prevent someone from getting it back, or maybe me from getting it back. It feels pretty good."
The approach seems counterintuitive -- if the body's natural immune response could combat the cancer, the tumor should have perished and never needed treatment. A more vigorous defense is needed, said Parsa.
"We are purifying the protein, to allow the immune system to see it better," he said. "It's like shining a little bit of light on stage, to say, 'Here, go get them.' "
If it works, it will reinvigorate a strategy for treating cancer that has long held conceptual promise but has proved difficult to deliver.
Many experimental vaccines have stumbled in clinical trials and none is yet approved in the United States. One of the greatest disappointments was in 2005, when final testing of the anti-melanoma vaccine Canvaxin showed that people getting the drug did not live longer than those getting the placebo. This year, a drug named Provenge, an immunotherapy for prostate cancer, has been shown to lengthen life for four months but has not yet earned approval by the U.S. Federal Drug Administration.
Scientists say that one challenge is that most drugs in development are first evaluated in patients with fairly advanced cancer -- but many of these patients are so sick that they're immunosuppressed. Cancer vaccines may work better when the tumor is smaller, they say.
Scientists say they're gaining greater understanding of the complexity of tumors and immunity, so they still believe that immune-priming strategies continue to hold great promise. They can better identify and isolate the particular proteins that are most useful, they say.
"You have to have the right type of vaccine, the right type of cancer, the right type of patient and the right type of environment for that patient," Parsa said. "A lot of the work is to figure out who is best suited, or not.
"Every tumor is different," he said. "It may take more than one approach to provoke long-term remission from cancer."
Contact Lisa M. Krieger at 408-920-5565.
FOR MORE ABOUT THE STUDY
For more information on the study, call 415-353-7500 or e-mail ParsaA@neurosurg.ucsf.edu. To see more of the San Jose Mercury News, or to subscribe to the newspaper, go to http://www.mercurynews.com. Copyright (c) 2009, San Jose Mercury News, Calif. Distributed by McClatchy-Tribune Information Services. For reprints, email tmsreprints@permissionsgroup.com, call 800-374-7985 or 847-635-6550, send a fax to 847-635-6968, or write to The Permissions Group Inc., 1247 Milwaukee Ave., Suite 303, Glenview, IL 60025, USA.
Copyright (C) 2009, San Jose Mercury News, Calif.