ORLANDO -- An investigational therapeutic vaccine for pancreatic cancer extended survival after surgery by about six to seven months, researchers reported here.
ORLANDO, Jan. 22 -- An investigational therapeutic vaccine for pancreatic cancer extended survival after surgery by about six to seven months, researchers reported here.
The median overall median survival for patients who received the vaccine was 26.8 months versus historical survival of about 20 months, said Daniel A. Laheru, M.D., of Johns Hopkins.
Eighty-eight percent of the patients who received the vaccine survived for a year, and the two-year survival rate was 76%, Dr. Laheru said at a gastrointestinal cancer symposium. Published trials of patients treated with surgery alone reported an average one-year survival of 63% and a two-year survival rate of 42%.
The vaccine, which is administered by infusion, consists of lethally irradiated lines of pancreatic cancer cells that are engineered to secrete granulocyte macrophage colony stimulating factor (GM-CSF).
The protein draws immune cells to the vaccination site where they are exposed to pancreas cancer antigens. Theoretically, the immune cells, acting like bloodhounds that have picked up a scent, then track and destroy pancreas cancer cells throughout the body.
The 60-patient phase II trial reported here followed by six years a phase I trial of in nine patients. "Three patients from the phase I trial are still alive," Dr. Laheru said. "The dose used in those three patients was the dose carried forward to the phase II trial."
Patients were recruited from those who were cancer-free for 30 days following pancreatic resection by Hopkins surgeons. The initial infusion of 25 million cells from each of two cell lines was administered eight to 10 weeks after surgery.
Patients were then treated with a standard regimen of 5FU (5-fluorouracil)-based chemoradiation for 26 weeks. Patients who were cancer-free for 30 days following the completion of chemoradiation, received three more infusions of the vaccine, each infusion one month apart.
A fifth and final booster infusion was administered six months after the fourth vaccination.
"Our initial review suggests that the vaccine could provide additional benefit over chemoradiotherapy, but prospective randomized trials are needed to confirm this observation," Dr. Laheru said.
He said the Hopkins researchers were reviewing the data before moving forward with phase III studies, but he predicted that phase III trials could begin as soon as late 2007.
Charles Staley, M.D., chief of surgical oncology at Emory in Atlanta, termed the results promising, noting that adding six to seven month to survival was important. Surgeons, he said, "seem to have hit a wall and cannot get our pancreatic cancer patients past 18 to 19 months after surgery."
Dr. Staley, who was not involved in the study, moderated a press conference where the results were discussed.
Dr. Laheru acknowledged that the single-center design of the trial was a limitation. Critics, he said, "point out that the surgery was done at Hopkins where our surgeons perform thousands of these operations, suggesting that the benefit we report might just reflect better surgery, rather than a benefit from the vaccine."
He said, however, that he was confident that the vaccine could increase survival of patients who have surgery by experience surgeons "at any center, not just Hopkins."
The Gastrointestinal Cancer Symposium is jointly sponsored by the American Society of Clinical Oncology, the American Society for Therapeutic Radiology and Oncology, the American Gastroenterological Association Institute, and the Society of Surgical Oncology.