Therapeutic Vaccine Improves Survival in Patients with Pancreatic Cancer

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CONFERENCE COVERAGE:

2007 Gastrointestinal Cancers Symposium

Therapeutic Vaccine Improves Survival in Patients with Pancreatic Cancer

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ew pancreatic cancer vaccine findings were presented at the 2007 Gastrointestinal Cancers Symposium, held January 19-21 in Orlando, FL. The Gastrointestinal Cancers Symposium is cosponsored by the American Society of Clinical Oncology (ASCO) the American Society for Therapeutic Radiology and Oncology (ASTRO), the American Gastroenterological Association (AGA) Institute, and the Society of Surgical Oncology (SSO).

In the study presented at the symposium, investigators used the vaccine in addition to conventional surgery and postoperative

chemotherapy and radiation therapy in 60 patients with pancreatic cancer (n=454). The vaccine was injected 8 to 10 weeks after surgery, with four boosters given in the 9 months after chemotherapy and radiation therapy.

Most of the patients who received the vaccine survived at least 2 years, Dr. Daniel Laheru of Johns Hopkins University in Baltimore and colleagues told a meeting of gastrointestinal cancer specialists. In the phase II study of 60 patients, 88% were alive a year later and 76% lived 2 years. In comparison, 63% of patients treated with surgery alone survive a year and 42% live 2 years.

The vaccine appeared to be well tolerated. Side effects were limited to itching, redness, and swelling at the injection site, and typically dissipated within 10 days.

According to Dr. Laheru, “Our initial review suggests that the vaccine could provide additional benefit over chemoradiotherapy, but prospective randomized trials are needed to confirm this observation.”

Pancreatic cancer is one of the deadliest cancers. In the US alone, it will be newly diagnosed in 37,170 patients and will kill

33,370, according to the American Cancer Society.

Dr. Laheru’s research team developed a therapeutic vaccine—one that fights a disease by boosting the immune system rather

than preventing the disease. The vaccine was developed by taking cells from the tumor cells of patients, killing the cells with

radiation, and then genetically engineering the cells so they could produce granulocyte macrophage colony-stimulating factor (GMCSF). GM-CSF is a protein secreted by macrophages that stimulates stem cells to product granulocytes and macrophages. It attracts immune cells to the vaccine site, where they find and learn to recognize pancreatic cancer proteins. Then the immune cells “patrol” the rest of the patient’s body and, in theory, destroy pancreatic tumor cells.

“Usually, pancreatic cancer cells fly under the radar of the immune system, evading the body’s surveillance mechanisms,” stated Dr. Laheru. “The cancer cells, which weren’t previously recognized as foreign by immune cells, are now recognized as being foreign,” Laheru said. The newly developed vaccine represents a potential means of making the pancreatic cancer cells immunogenic. These results are impressive and warrant further research.

The research was funded by the National Cancer Institute and Cell Genesys Inc., which makes the vaccine under the name GVAX™.