The University of Pittsburgh Cancer Institute has announced initial success in a human clinical trial involving a new Pitt vaccine to boost the immune response against colon cancer.
"This prophylactic colon cancer vaccine boosts the patient's natural immune surveillance, which potentially could lead to the elimination of premalignant lesions before their progression to cancer," Olivera Finn, who developed the vaccine, and heads the Department of Immunology at Pitt's School of Medicine, said in a press release. "This might spare patients the risk and inconvenience of repeated invasive surveillance tests, such as colonoscopy, that currently are used to spot and remove precancerous polyps."
Colon cancer typically starts with a polyp, an abnormal but benign growth in the colon.
But polyps that become cancerous, known as adenomas, typically are removed before cancer develops, a key reason doctors recommend regular colonoscopies for people 50 and older.
The study focused on those with a history of advanced adenomas that places them at higher risk of developing colon cancer. Thirty to 40 percent of such patients develop a new polypi within three years, Robert E. Schoen, professor of medicine and epidemiology with Pitt's division of gastoenterology, hepatology and nutrition, and the study's clinical leader, said in the press release.
"In this study, we demonstrated the ability of the vaccine to boost immunity," he said in the press release. "Subsequent trials need to evaluate the vaccine for its ability to lower or prevent polyp recurrence and thus progression to colon cancer."
Funded by the National Cancer Institute and the National Institutes of Health, the study is published in the January edition of Cancer Prevention Research.
The vaccine was tested on 39 patients, who were between 40 and 70 years old and who had histories of advanced adenomas or polyps.
The vaccine produced a strong protective response in 17 patients, or 44 percent.
The lack of response in the other 22 patients likely was due "to already high levels of cells that suppress the immune system's ability to fight cancer," according to the press release, suggesting that it might be more successful to vaccinate people at an earlier stage or those people whose immune systems aren't already suppressed by the cells activated in the process leading to colon cancer.
The vaccine attacks an abnormal variant of a cell protein called MUC1, which is altered and produced in excess in advanced adenomas and cancer.
The same protein also is present in abnormal levels in pancreatic, breast, lung and prostate cancer and will be tested in the future in patients with premalignant lesions leading to some of these cancers.
The well-tolerated vaccine, and the success to date, will lead to a larger randomized trial to examine how effective it is in preventing polyps.
According to the NCI, colorectal cancer is the third-leading cause of cancer death in the United States, with expectations of 103,170 new cases in 2012 and 40,280 new cases of rectal cancer.
The overall lifetime risk of developing colorectal cancer is 1 in 20. It is expected to cause about 51,690 deaths this year.
David Templeton: email@example.com or 412-263-1578.