• ORLANDOAn investigational therapeutic vaccine (GVAX immunotherapy) given with chemotherapy and radiation therapy following surgery for pancreatic cancer appears to improve survival for these difficult-to-treat patients, according to the results of a phase II trial presented at the 2007 Gastrointestinal Cancers Symposium (abstract 106) (see image).
With a 3-year median follow-up, patients who received the vaccine had an overall median survival of 26.8 months, compared with about 20 months for historical controls, said Daniel A. Laheru, MD, assistant professor of medicine, Johns Hopkins Medical Institutions. Disease-free survival was 18.8 months.
The vaccine consists of lethally irradiated allogeneic pancreatic tumor cells engineered to secrete granulocyte macrophage colony-stimulating factor (GM-CSF). The GM-CSF molecule attracts immune cells to the vaccine site, where they encounter pancreatic cancer antigens. They then patrol the rest of the patient's body to destroy pancreatic tumor cells with the same antigen profile. Allogeneic cells were used because not enough tumor cells could be derived from each individual patient, Dr. Laheru said.
In a phase I dose-finding trial performed 6 years ago in 14 patients with pancreatic cancer who received the vaccine in addition to chemoradiotherapy following surgery, the vaccine was well tolerated, and there were three long-term survivors, all of whom received the highest dose, Dr. Laheru said.
The current phase II study involved 60 Johns Hopkins patients with operable disease: 53 patients were lymph node positive and 18 were margin positive.
All patients received their first vaccine injection 8 to 10 weeks after surgery. They subsequently were treated with fluorouracil-based chemotherapy and radiation therapy for 26 weeks. Patients who were disease free 1 month after completion of their chemoradiation then received three additional vaccine doses 1 month apart, followed by a fifth vaccine booster 6 months later.