Vaccine trial launched for previously untreated metastatic disease.

2003 JUN 11 - (NewsRx.com & NewsRx.net) -- Cancer can be difficult to treat because it tricks the immune system into thinking it's not a threat. Researchers at the Columbia Presbyterian Medical Center at New York-Presbyterian Hospital are participating in a study with a new vaccine that they hope will fool the immune system into fighting colorectal cancer.

Unlike traditional vaccines that are designed to prevent disease by preparing the immune system for a possible attack, this innovative therapeutic colorectal cancer vaccine - ALVAC-CEA/B7.1 - is designed to "turn on" the immune system of people who already have the disease but who have not yet been treated. This therapeutic approach differs from the use of other cancer vaccines, which have been used only as last resorts when chemotherapy and other treatments have failed.

"The goal of the study is to determine if the vaccine can activate the body's own immune system to eliminate cancer cells that may not be eliminated with traditional treatment of metastatic colorectal cancer with standard first-line chemotherapy," explained Howard L. Kaufman, MD, vice chairman of surgical oncology at Columbia Presbyterian Medical Center, associate professor of clinical surgery at Columbia University College of Physicians & Surgeons, and principal investigator of the study.

"We will be looking to see if the vaccine, combined with chemotherapy, allows a better outcome for these patients than chemotherapy alone," he added.

Since cancer cells do not appear very different from normal cells to the immune system, they are largely tolerated rather than destroyed. However, the surfaces of many cancer cells have special proteins or antigens that can serve as potential targets for an immune response. ALVAC-CEA/B7.1, a deactivated strain of the canarypoxvirus, is of interest to cancer researchers because of the antigens it displays, which are identical to the antigens exhibited by colorectal tumors. This carcinoembryonic antigen (CEA) is found on the surface of about 95% of colorectal cancer cells.

The body's immune system should normally fight cells displaying these antigens, but many people with colorectal cancer have immune systems that don't recognize these cells as a threat, and therefore, don't fight them. The idea behind the vaccine is to introduce even more of the tumor-associated antigens (TAA) into the body so the immune system becomes "awakened" or "trained" to attack the cancer cells.

ALVAC-CEA is designed to produce a short-lived and self-limiting harmless infection that causes ...