Beating Tumors at Their Own Game
Date: March 1, 2010
Tumors are tricky things, and pancreatic tumors especially so. With an ability to deceive and ultimately thwart the body’s immune system, pancreatic cancer has long held the upper hand against physicians and patients fighting the disease.
Even in those rare cases when surgeons successfully remove the tumor, the cancer often returns in full force.
Consequently, a diagnosis of pancreatic cancer is often tantamount to a death sentence, if not in the first go-round then the next, usually less than a decade after the initial diagnosis. Now, though, a vaccine developed by Johns Hopkins researchers could potentially weight the fight in the immune system’s favor.
During a clinical trial 10 years ago, a group of Hopkins researchers led by oncologist Elizabeth Jaffee distributed an experimental pancreatic cancer vaccine to 10 patients. As is often expected in pancreatic cancer diagnoses, several of those patients eventually suffered recurrences and died. But today, three remain alive and cancer-free, and all signs point toward the vaccine as the cause.
“With pancreatic cancer, that’s exceedingly rare,” says surgical oncologist Barish Edil. “The five-year survival rate for this disease is only around 20 percent, and the 10-year rate, well, that is quite rare.”
Edil, joined by a group of oncology colleagues, has taken the helm of the clinical trial’s second phase, which is now in its second year. He’s also altered the approach.
In the trial’s first incarnation, the vaccine was distributed only after patients had undergone a Whipple operation and received chemotherapy. Now, however, patients receive one vaccine dose before surgery and right after, followed by four more vaccinations after chemotherapy.
The presurgery vaccinations offer several advantages in treating the disease, Edil says. First and most obviously, the body receives an immune boost that could prove helpful as patients deal with the threefold challenge of fighting the cancer, undergoing major surgery and coping with chemotherapy and radiation. And, of course, there’s the hope that the tough vaccine regimen will fight off cancer recurrence. But it’s a third benefit that’s proving most exciting for Edil and his colleagues: the chance to reach out to patients before surgery allows physicians to observe the effects the vaccine has on the tumor postoperatively.
“The five-year survival rate for this disease is only around 20 percent, and the 10-year rate, well, that is quite rare.” —Barish Edil
Since the trial opened, 22 patients have received the vaccine. Examinations of the patients’ tumors have shown that each has developed disease-fighting lymph nodes, a sure sign that the immune system is battling harder and more effectively than has ever been possible before.
“We have the immune system working to kill the cancer cells,” Edil says. “This is the first time we’ve ever seen that, plus we have long-term survivors now, which is especially unique. Our hope is that the body is revved up so that when the cancer comes back, which it does with pancreatic cancer quite often, the immune system will be able to kill those cells as well.”
Of course, there are still improvements to be made.
For instance, despite any immune-boosting effects the vaccine may have, chemotherapy and radiation treatments ultimately thwart the immune system all over again.
“We’ve shown that even after we give the vaccine, once we start giving patients chemo and radiation therapy, certain cells that attack cancer go down again,” Edil explains. “We have to figure out how to integrate the two treatments so that they work well together.”