dr. sampson says he has patients who have lived five years on the vaccine. lee sullivan is hoping to do better than that. >> there's no evidence of recurrence at this time. >> i'm almost 12 months into my treatments now feeling great, doing very well. >> reporter: i can tell you, katie, this is promising stuff. it's a small study so far, just 18 patients in this first trial, but this is how it works. they're going to go to a phase three trial next, more patients, they're going to expand it, and hopefully see some of the same results. >> couric: and, sanjay, a lot of people of course think of vaccines for preventing disease but they're being usinged increasingly to treat cancer and what's really exciting about this vaccine is the protein it's targeting is actually present in other kinds of cancer. >> reporter: that's right. there's a protein on these cancer cells. it's not present in any other normal tissue in the body. that's what makes it so important. that's what makes it a target, potentially, for these immediates and not only in brain cancer but also lung, breast, an