A novel vaccine that encourages the immune system to seek out and destroy tumor cells shows promise for treating pancreatic cancer.
In a new study, pancreatic cancer patients who were given the experimental vaccine lived an average of 27 months.
That may not sound like much, but pancreatic cancer is the fourth deadliest cancer, with most victims surviving only 18 or 19 months after diagnosis, says Charles A. Staley, MD, head of surgical oncology at Emory University in Atlanta.
“With pancreatic cancer, we’ve been failing for so long,” he tells WebMD. “Most advances are the results of baby steps like this.”
Staley, who was not involved with the work, moderated a news conference to discuss the findings at the 2007 Gastrointestinal Cancer Symposium being held here.
How the Vaccine Works
Unlike flu and many other vaccines, most cancer vaccines under development are not intended to be given to healthy people to prevent disease.
Rather, they help sick patients bolster their immune system to better fight the cancer.
In this case, the goal is to re-educate the immune system to recognize pancreatic cancer cells as foreign invaders that need to be attacked and annihilated, says researcher Daniel A. Laheru, MD, an assistant professor at the Johns Hopkins Kimmel Cancer Center.
Usually, pancreatic cancer cells fly under the radar of the immune system, evading the body’s surveillance mechanisms, he tells WebMD.
Educating Immune Cells
To overcome that obstacle, the injectable vaccine uses irradiated pancreatic cancer cells that can no longer grow but are genetically altered to lure the body's immune cells.
When the immune cells encounter the irradiated cancer cells, they go to war.
“The cancer cells, which weren’t previously recognized as foreign by immune cells, are now recognized as being foreign,” Laheru says.
The revved-up immune cells go on the offensive, not only wiping out the irradiated cancer cells that have been injected into the patient, but also patrolling the body and killing off active cancer cells in their path.
Tested in 60 Patients
For the new study, researchers used the vaccine in addition to conventional surgery and postoperative chemotherapy and radiation in 60 people with pancreatic cancer.
The vaccine was injected eight to 10 weeks after surgery, with four boosters given in the nine monthsafter chemotherapy and radiation.
Over the next two years, 24 percent of the participants died.
For comparison, 58 percent of people who get surgery alone (without the vaccine or chemotherapy and radiation) would be expected to die over the two-year period, Laheru says.
Few Side Effects
Because the vaccine targets only tumor cells, healthy cells are generally left unscathed.
That means many unpleasant side effects, such as hair loss and nausea, associated with traditional cancer medications are avoided, Laheru says.
In fact, side effects were limited to itching, redness, and swelling at the injection site and typically dissipated within 10 days.
The research was funded by the National Cancer Institute and Cell Genesys Inc., which makes the vaccine under the name GVAX.
Laheru cautions that further study is needed before the vaccine is ready for prime time.
If it does pan out, he adds, it will most likely be used as a complement to surgery, chemotherapy, and radiation.
Chemo and Radiation Advised
In the U.S., most pancreatic cancer victims who undergo surgery are given chemotherapy and radiation afterward -- and another study presented at the meeting suggests this approach is advisable.
The study included 454 people who underwent surgery for pancreatic cancer; about half also got postoperative chemotherapy and radiation.
Five years later, 28 percent of those who got the triple punch were still alive, compared with only 17 percent who got surgery alone.
“After surgery to remove pancreatic cancer, there is a survival benefit to adding radiation therapy and chemotherapy,” researcher Michele M. Corsini, MD, of the Mayo Clinic tells WebMD.
By Charlene Laino, reviewed by Louise Chang, MD
SOURCES: 2007 Gastrointestinal Cancer Symposium, Orlando, Jan. 19-21, 2007. Daniel A. Laheru, MD, assistant professor, Johns Hopkins Kimmel Cancer Center, Baltimore. Charles A. Staley, MD, chief, division of surgical oncology, Emory University, Atlanta. Michele M. Corsini, MD, Mayo Clinic, Rochester, Minn.