Researchers test cancer vaccine

Pitt researchers have gotten closer to finding a cure for colon cancer.

Robert Schoen, a… Pitt researchers have gotten closer to finding a cure for colon cancer.

Robert Schoen, a Pitt professor of medicine and epidemiology, and Olivera Finn, a professor in Pitt’s School of Medicine, are leading a team that began testing a vaccine on humans that might prevent the pre-malignant polyps that form in the colon and turn into cancer.

Colon cancer, which results in more than 650,000 deaths each year, is the second leading cause of cancer-related deaths in the Western world, according to the World Health Organization.

The premise of the vaccine follows the old cliche of ‘nipping a problem in the bud.’

The vaccine targets an abnormal variant of a self-made cell protein called MUC1. The protein normally secretes mucin in the lining of the colon, protecting cells from the harsh environment of the ducts.

Picture the cell that produces the MUC1 protein as a factory machine. If that machine breaks or gets damaged in some way, the product it produces will come out wrong. Pre-cancerous polyps form when something goes wrong with the cells that make MUC1.

‘And so in other words, changes in the MUC1 mirror the changes of the body developing a polyp and developing a cancer,’ said Schoen, the head clinician working on the vaccine. ‘The hope is that if one could eliminate the cells that are producing these abnormal proteins and these cells that are associated with the development of cancer, that one could in some way interrupt the cancer-polyp sequence.’

Finn, the head researcher on this trial, has worked with the MUC1 protein for 20 years now. The vaccine initially started off as one for pancreatic cancer. It had some success prolonging the lives of pancreatic cancer patients and preventing their cancer from recurring.

But like all other vaccines, the colon cancer vaccine is expected to be the most successful at preventing the cancer from developing.

‘The colon cancer is the only cancer right now where the pre-malignant steps are so defined,’ said Finn. ‘So we can choose a stage [polyps] of the cancer to apply the vaccine. In the other cancers, we don’t have this information yet.’

Schoen said hopefully with the vaccine, ‘you can generate an immune response to these abnormal molecules that will prevent polyps from recurring. And if the polyps don’t recur, then the pathway to cancer is stopped. So you’re preventing colon cancer by preventing the initial changes.’

Finn said if the vaccine does work, doctors can focus their treatment on people who have a high risk for colon cancer at a young age.

‘You don’t even have to do the colonoscopy, for example, if somebody has a lot of colon cancer in the family,’ she said.

Since the vaccine trial’s start in November, 12 people have received the vaccine. The researchers plan to enroll another 50 or so into the study. Participants are between 40 and 70 years old and have a history of developing the pre-cancerous polyps.

After receiving the vaccine, patients are monitored for immune responses to the abnormal MUC1 protein at two-week, 10-week, 12-week, 28-week and one-year intervals.

Finn, who received her doctorate from Stanford University, is 59 now. While she doesn’t believe that prophylactic cancer vaccines will exist among other vaccines in her lifetime, she hopes the next generation will benefit from them.

‘This is the work of my life. I’m optimistic that that will happen,’ she said. ‘Fifteen years ago when I talked about a vaccine for cancer prevention, people thought that we were talking about science fiction. It is not science fiction anymore.’