Several additional cancer centers in the United States and Canada are enrolling patients in an innovative clinical trial evaluating the use of a therapeutic cancer vaccine in patients with first-line metastatic colorectal cancer.In addition, a second trial using the vaccine earlier in the course of disease is now under way in centers across Canada, according to Aventis Pasteur Limited of Toronto, Canada, the study sponsor.

Both studies are designed to determine how the investigational vaccine, ALVAC-CEA/B7.1, can be most effective when integrated with standard chemotherapy regimens to treat colon cancer.ALVAC-CEA/B7.1 is a unique cancer vaccine under development that uses a viral vector system derived from the canarypox virus.It is engineered to target the carcinoembryonic antigen (CEA), which is a protein that is overexpressed on the surface of the majority of colorectal cancer cells.

"We are committed to pursuing multiple routes to determine whether ALVAC-CEA/B7.1 has a role in improving overall outcomes when used with chemotherapy to treat colon cancer," said Neil Berinstein, Assistant Vice President Clinical Oncology, Program Director, Cancer, Aventis Pasteur. "By adding more trial locations for our first study, and initiating the second study, we are demonstrating our confidence in moving the ALVAC vaccine forward."

Colorectal cancer is the most common cancer of the gastrointestinal tract and the second leading cause of cancer-related morbidity and mortality.There are approximately 300,000 new cases and 200,000 deaths in North America and Europe each year.An estimated 70% of patients are initially diagnosed with treatable forms of the disease, but 25% of these patients will still experience recurrence, which frequently leads to death due to metastatic disease.